diff --git a/pom.xml b/pom.xml
index 5aaef21..7fd4a5a 100644
--- a/pom.xml
+++ b/pom.xml
@@ -133,10 +133,10 @@
             <version>${lombok.version}</version>
             <scope>compile</scope>
         </dependency>
-        <dependency>
-            <groupId>javax.persistence</groupId>
-            <artifactId>javax.persistence-api</artifactId>
-            <version>2.2</version>
-        </dependency>
+<!--        <dependency>-->
+<!--            <groupId>javax.persistence</groupId>-->
+<!--            <artifactId>javax.persistence-api</artifactId>-->
+<!--            <version>2.2</version>-->
+<!--        </dependency>-->
     </dependencies>
 </project>
\ No newline at end of file
diff --git a/src/main/java/jef/model/DbEntity.java b/src/main/java/jef/model/DbEntity.java
index 56000ec..ae041a1 100644
--- a/src/main/java/jef/model/DbEntity.java
+++ b/src/main/java/jef/model/DbEntity.java
@@ -4,6 +4,11 @@ import jef.asm.AsmParseException;
 import jef.asm.AsmParser;
 import jef.expressions.Expression;
 import jef.expressions.IntermediateFieldExpression;
+import jef.model.constraints.ForeignKeyConstraint;
+import jef.model.constraints.IndexConstraint;
+import jef.model.constraints.KeyConstraint;
+import jef.model.constraints.PrimaryKeyConstraint;
+import jef.model.constraints.UniqueConstraint;
 import jef.serializable.SerializableFunction;
 import jef.serializable.SerializableObject;
 import lombok.Getter;
@@ -17,18 +22,23 @@ import java.util.List;
 @Getter
 @Setter
 public class DbEntity<T extends SerializableObject> {
-    private final Class<T> entityClazz;
+    private final Class<T> type;
     private final List<DbField<?>> fields;
     private String name;
+    private PrimaryKeyConstraint primaryKey;
+    private final List<ForeignKeyConstraint> foreignKeys = new ArrayList<>();
+    private final List<UniqueConstraint> uniqueKeys = new ArrayList<>();
+    private final List<KeyConstraint> keys = new ArrayList<>();
+    private final List<IndexConstraint> indexes = new ArrayList<>();
 
-    public DbEntity(Class<T> entityClazz) {
-        this(entityClazz, new ArrayList<>());
+    public DbEntity(Class<T> type) {
+        this(type, new ArrayList<>());
     }
 
-    public DbEntity(Class<T> entityClazz, List<DbField<?>> fields) {
-        this.entityClazz = entityClazz;
+    public DbEntity(Class<T> type, List<DbField<?>> fields) {
+        this.type = type;
         this.fields = fields;
-        this.name = entityClazz.getSimpleName();
+        this.name = type.getSimpleName();
     }
 
     public List<DbField<?>> getFields() {
@@ -48,16 +58,20 @@ public class DbEntity<T extends SerializableObject> {
         return prop;
     }
 
+    public <R> DbField<R> getField(Field field) {
+        return (DbField<R>) fields.stream().filter(e -> e.getField().equals(field)).findFirst().orElse(null);
+    }
+
     public <R> DbField<R> getOrCreateField(SerializableFunction<T, R> getter) {
         try {
             var prop = getField(getter);
             if (prop == null) {
                 var name = extractFieldName(getter);
-                var field = ReflectionUtil.getFieldsRecursive(entityClazz).stream().filter(f -> f.getName().equals(name)).findFirst().orElse(null);
+                var field = ReflectionUtil.getFieldsRecursive(type).stream().filter(f -> f.getName().equals(name)).findFirst().orElse(null);
                 if (field == null) {
                     throw new RuntimeException("Field not found: " + name);
                 }
-                prop = new DbField<>((Class<R>) field.getType(), field);
+                prop = new DbField<>(this, (Class<R>) field.getType(), field);
                 fields.add(prop);
             }
             return prop;
@@ -66,11 +80,24 @@ public class DbEntity<T extends SerializableObject> {
         }
     }
 
-    public <R> DbField<R> getOrCreateField(Field f) {
+    public <R> DbField<R> getOrCreateField(Field field) {
         try {
-            var prop = (DbField<R>) fields.stream().filter(e -> e.getField() == f).findFirst().orElse(null);
+            var prop = (DbField<R>) fields.stream().filter(e -> e.getField() == field).findFirst().orElse(null);
             if (prop == null) {
-                prop = new DbField<>((Class<R>) f.getType(), f);
+                prop = new DbField<>(this, (Class<R>) field.getType(), field);
+                fields.add(prop);
+            }
+            return prop;
+        } catch (Exception e) {
+            throw new RuntimeException("Invalid expression", e);
+        }
+    }
+
+    public <R> DbField<R> getOrAddField(DbField<R> field) {
+        try {
+            var prop = (DbField<R>) fields.stream().filter(e -> e.getName().equals(field.getName())).findFirst().orElse(null);
+            if (prop == null) {
+                prop = field;
                 fields.add(prop);
             }
             return prop;
@@ -91,4 +118,20 @@ public class DbEntity<T extends SerializableObject> {
             throw new RuntimeException("Invalid expression", e);
         }
     }
+
+    public void addForeignKey(ForeignKeyConstraint foreignKey) {
+        foreignKeys.add(foreignKey);
+    }
+
+    public void addUniqueContstraint(UniqueConstraint uniqueConstraint) {
+        uniqueKeys.add(uniqueConstraint);
+    }
+
+    public void addIndex(IndexConstraint index) {
+        indexes.add(index);
+    }
+
+    public void addKey(KeyConstraint key) {
+        keys.add(key);
+    }
 }
diff --git a/src/main/java/jef/model/DbField.java b/src/main/java/jef/model/DbField.java
index 45802e4..3e59f88 100644
--- a/src/main/java/jef/model/DbField.java
+++ b/src/main/java/jef/model/DbField.java
@@ -1,21 +1,75 @@
 package jef.model;
 
+import jef.model.constraints.IndexConstraint;
+import jef.model.constraints.KeyConstraint;
+import jef.model.constraints.UniqueConstraint;
+import jef.serializable.SerializableObject;
 import lombok.Getter;
 import lombok.Setter;
 
 import java.lang.reflect.Field;
+import java.util.ArrayList;
+import java.util.List;
 
 @Getter
 @Setter
 public class DbField<T> {
-    private final Class<T> propertyClazz;
+    private final DbEntity<? extends SerializableObject> entity;
+    private final Class<T> type;
     private final Field field;
     private String name;
     private boolean notNull = false;
 
-    public DbField(Class<T> propertyClazz, Field field) {
-        this.propertyClazz = propertyClazz;
+    public DbField(DbEntity<? extends SerializableObject> entity, Class<T> type, Field field) {
+        this.entity = entity;
+        this.type = type;
         this.field = field;
         this.name = field.getName();
     }
+
+    public DbField(DbEntity<? extends SerializableObject> entity, Class<T> type, Field field, String name) {
+        this.entity = entity;
+        this.type = type;
+        this.field = field;
+        this.name = name;
+    }
+
+    public boolean isUnique() {
+        return entity.getUniqueKeys().stream().anyMatch(u -> u.getFields().size() == 1 && u.getFields().get(0) == this);
+    }
+
+    public void setUnique(boolean unique) {
+        var constr = entity.getUniqueKeys().stream().filter(u -> u.getFields().size() == 1 && u.getFields().get(0) == this).findFirst();
+        if (!constr.isPresent() && unique) {
+            entity.getUniqueKeys().add(new UniqueConstraint(entity, new ArrayList<>(List.of(this))));
+        } else if (constr.isPresent() && !unique) {
+            entity.getUniqueKeys().remove(constr.get());
+        } //else do nothing
+    }
+
+    public boolean isIndex() {
+        return entity.getIndexes().stream().anyMatch(u -> u.getFields().size() == 1 && u.getFields().get(0) == this);
+    }
+
+    public void setIndex(boolean indexed) {
+        var constr = entity.getIndexes().stream().filter(u -> u.getFields().size() == 1 && u.getFields().get(0) == this).findFirst();
+        if (!constr.isPresent() && indexed) {
+            entity.getIndexes().add(new IndexConstraint(entity, new ArrayList<>(List.of(this))));
+        } else if (constr.isPresent() && !indexed) {
+            entity.getIndexes().remove(constr.get());
+        } //else do nothing
+    }
+
+    public boolean isKey() {
+        return entity.getKeys().stream().anyMatch(u -> u.getFields().size() == 1 && u.getFields().get(0) == this);
+    }
+
+    public void setKey(boolean keyed) {
+        var constr = entity.getKeys().stream().filter(u -> u.getFields().size() == 1 && u.getFields().get(0) == this).findFirst();
+        if (!constr.isPresent() && keyed) {
+            entity.getKeys().add(new KeyConstraint(entity, new ArrayList<>(List.of(this))));
+        } else if (constr.isPresent() && !keyed) {
+            entity.getKeys().remove(constr.get());
+        } //else do nothing
+    }
 }
diff --git a/src/main/java/jef/model/ModelBuilder.java b/src/main/java/jef/model/ModelBuilder.java
index 4ead7c8..6c24415 100644
--- a/src/main/java/jef/model/ModelBuilder.java
+++ b/src/main/java/jef/model/ModelBuilder.java
@@ -2,26 +2,35 @@ package jef.model;
 
 import jef.DbSet;
 import jef.model.annotations.Clazz;
+import jef.model.annotations.Id;
+import jef.model.annotations.Transient;
 import jef.model.annotations.processors.AnnotationProcessor;
+import jef.model.annotations.processors.IndexProcessor;
+import jef.model.annotations.processors.KeyProcessor;
 import jef.model.annotations.processors.NotNullProcessor;
+import jef.model.annotations.processors.UniqueProcessor;
+import jef.model.constraints.ForeignKeyConstraint;
+import jef.model.constraints.PrimaryKeyConstraint;
 import jef.serializable.SerializableObject;
 
-import javax.persistence.Transient;
 import java.lang.reflect.Field;
 import java.util.ArrayList;
 import java.util.Collection;
 import java.util.Collections;
 import java.util.List;
+import java.util.Locale;
 
 public class ModelBuilder {
     private static final List<AnnotationProcessor> annotationProcessors = new ArrayList<>();
 
     static {
         annotationProcessors.add(NotNullProcessor.INSTANCE);
+        annotationProcessors.add(UniqueProcessor.INSTANCE);
+        annotationProcessors.add(IndexProcessor.INSTANCE);
+        annotationProcessors.add(KeyProcessor.INSTANCE);
     }
 
-
-    public static ModelBuilder from(DbContext context) {
+    public static ModelBuilder from(Class<? extends DbContext> context) {
         try {
             return from0(context);
         } catch (Exception e) {
@@ -29,54 +38,140 @@ public class ModelBuilder {
         }
     }
 
-    private static ModelBuilder from0(DbContext context) throws Exception {
+    private static ModelBuilder from0(Class<? extends DbContext> context) throws Exception {
         var mb = new ModelBuilder(new ArrayList<>());
-        for (Field ctxfield : context.getClass().getDeclaredFields()) {
-            System.out.println(ctxfield);
-            if (!DbSet.class.isAssignableFrom(ctxfield.getType())) {
-                continue;
-            }
-            Clazz clazzAnnontation = ctxfield.getAnnotation(Clazz.class);
-            if (clazzAnnontation == null) {
-                throw new ModelException("DbSet " + ctxfield.getName() + " is missing the Clazz annotation");
-            }
-            var dbsetClazz = (Class<? extends SerializableObject>)clazzAnnontation.clazz();
-            var entity = mb.getOrCreateEntity(dbsetClazz);
+        initEntities(mb, context);
+        addPrimaryKeys(mb);
+        addForeignKeys(mb);
 
-            var fields = ReflectionUtil.getFieldsRecursive(dbsetClazz);
-            for (var f : fields) {
-                if (f.getAnnotationsByType(Transient.class).length > 0) {
-                    continue;
-                }
-                if (Collection.class.isAssignableFrom(f.getType())) {
-                    throw new UnsupportedOperationException();
-                } else {
-                    var dbField = entity.getOrCreateField(f);
-                    if (f.getType().isPrimitive()) {
-                        dbField.setNotNull(true);
-                    }
-                }
-            }
-        }
         for (AnnotationProcessor processor : annotationProcessors) {
             processor.apply(mb);
         }
         return mb;
-//        var entities = new HashMap<Class<? extends SerializableObject>, DbEntity<? extends SerializableObject>>();
-//        for (Field ctxfield : context.getClass().getDeclaredFields()) {
-//            if (!DbSet.class.isAssignableFrom(ctxfield.getClass())) {
-//                continue;
-//            }
-//            ctxfield.setAccessible(true);
-//            var dbset = (DbSet<? extends SerializableObject>) ctxfield.get(context);
-//            var dbsetClazz = dbset.getClazz();
-//            var fields = getFieldsRecursive(dbsetClazz);
-//            entities.put(dbsetClazz, createEntity(dbsetClazz, fields));
-//        }
-//
-//        return new ModelBuilder(new ArrayList<>(entities.values()));
     }
 
+    private static void initEntities(ModelBuilder mb, Class<? extends DbContext> context) {
+        for (Field ctxfield : context.getDeclaredFields()) {
+            if (!DbSet.class.isAssignableFrom(ctxfield.getType())) {
+                continue;
+            }
+            Clazz clazzAnnotation = ctxfield.getAnnotation(Clazz.class);
+            if (clazzAnnotation == null) {
+                throw new ModelException("DbSet " + ctxfield.getName() + " is missing the " + Clazz.class.getSimpleName() + " annotation");
+            }
+            var dbsetClazz = (Class<? extends SerializableObject>) clazzAnnotation.clazz();
+            initEntity(mb, dbsetClazz);
+        }
+    }
+
+    private static void initEntity(ModelBuilder mb, Class<? extends SerializableObject> clazz) {
+        var entity = mb.getOrCreateEntity(clazz);
+
+        var fields = ReflectionUtil.getFieldsRecursive(clazz);
+        for (var f : fields) {
+            if (f.getAnnotationsByType(Transient.class).length > 0) {
+                continue;
+            }
+            if (Collection.class.isAssignableFrom(f.getType())) {
+            } else {
+                var dbField = entity.getOrCreateField(f);
+                if (f.getType().isPrimitive()) {
+                    dbField.setNotNull(true);
+                }
+            }
+        }
+    }
+
+    private static void addPrimaryKeys(ModelBuilder mb) {
+        for (int i = 0; i < mb.getEntities().size(); i++) {
+            var entity = mb.getEntities().get(i);
+            addPrimaryKeys(mb, entity);
+        }
+    }
+
+    private static void addPrimaryKeys(ModelBuilder mb, DbEntity<?> entity) {
+        var fields = ReflectionUtil.getFieldsRecursive(entity.getType());
+        var idFields = new ArrayList<Field>();
+
+        //search for fields wuth @Id annotation
+        for (var f : fields) {
+            if (f.getAnnotationsByType(Transient.class).length > 0) {
+                continue;
+            }
+            if (!f.getType().isPrimitive()) {
+                continue;
+            }
+            if (f.getAnnotationsByType(Id.class).length == 0) {
+                continue;
+            }
+
+            //fields in same class check
+            if (idFields.size() == 0 || idFields.get(0).getDeclaringClass() == f.getDeclaringClass()) {
+                idFields.add(f);
+            } else {
+                break;
+            }
+        }
+
+        if (idFields.isEmpty()) {
+            for (var f : fields) {
+                if (f.getAnnotationsByType(Transient.class).length > 0) {
+                    continue;
+                }
+                if (!f.getType().isPrimitive()) {
+                    continue;
+                }
+                if (f.getName().equals("id")) {
+                    idFields.add(f);
+                    break;
+                }
+            }
+        }
+
+        if (!idFields.isEmpty()) {
+            var dbfields = idFields.stream().map(entity::getField).toList();
+            entity.setPrimaryKey(new PrimaryKeyConstraint(entity, (List) dbfields));
+        }
+    }
+
+    private static void addForeignKeys(ModelBuilder mb) {
+        for (int i = 0; i < mb.getEntities().size(); i++) {
+            var entity = mb.getEntities().get(i);
+            addForeignKeys(mb, entity);
+        }
+    }
+
+    private static void addForeignKeys(ModelBuilder mb, DbEntity<?> entity) {
+        var fields = ReflectionUtil.getFieldsRecursive(entity.getType());
+        for (var f : fields) {
+            if (f.getAnnotationsByType(Transient.class).length > 0) {
+                continue;
+            }
+            if (Collection.class.isAssignableFrom(f.getType())) {
+                Clazz clazzAnnotation = f.getAnnotation(Clazz.class);
+                if (clazzAnnotation == null) {
+                    throw new ModelException("Collection " + entity.getType().getSimpleName() + "." + f.getName() + " is missing the " + Clazz.class.getSimpleName() + " annotation");
+                }
+                var refEntity = mb.getEntity((Class<? extends SerializableObject>) clazzAnnotation.clazz());
+                if (refEntity == null) {
+                    initEntity(mb, (Class<? extends SerializableObject>) clazzAnnotation.clazz());
+                    refEntity = mb.getEntity((Class<? extends SerializableObject>) clazzAnnotation.clazz());
+                    addPrimaryKeys(mb, refEntity);
+                }
+                var primary = refEntity.getPrimaryKey();
+                if (primary == null) {
+                    throw new ModelException("Entity " + refEntity.getType().getSimpleName() + " is missing a primary key and therefore cannot be referenced by " + entity.getType().getSimpleName());
+                }
+                var refFields = primary.getFields().stream()
+                        .map(e -> new DbField<>(entity, e.getType(), null, f.getName() + e.getName().substring(0, 1).toUpperCase(Locale.ROOT) + e.getName().substring(1)))
+                        .map(entity::getOrAddField)
+                        .toList();
+                entity.addForeignKey(new ForeignKeyConstraint(entity, (List) refFields, refEntity, primary.getFields()));
+            }
+        }
+    }
+
+
     private final List<DbEntity<? extends SerializableObject>> entities;
 
     public ModelBuilder(List<DbEntity<? extends SerializableObject>> entities) {
@@ -95,7 +190,7 @@ public class ModelBuilder {
      * @return the database model for the requested class or null if not present.
      */
     public <T extends SerializableObject> DbEntity<T> getEntity(Class<T> clazz) {
-        return (DbEntity<T>) entities.stream().filter(e -> e.getEntityClazz() == clazz).findFirst().orElse(null);
+        return (DbEntity<T>) entities.stream().filter(e -> e.getType() == clazz).findFirst().orElse(null);
     }
 
     /**
diff --git a/src/main/java/jef/model/ReflectionUtil.java b/src/main/java/jef/model/ReflectionUtil.java
index d27bc1f..aeb4c2e 100644
--- a/src/main/java/jef/model/ReflectionUtil.java
+++ b/src/main/java/jef/model/ReflectionUtil.java
@@ -7,6 +7,15 @@ import java.util.Collection;
 import java.util.HashMap;
 
 class ReflectionUtil {
+    /**
+     * Returns a list of all declared fields of the given class.
+     * This also includes fields from super classes up until SerializableObject (exclusive).
+     * The fields within the same are not ordered in any particular way.
+     * The overall ordering is super class fields last, i.e., [...fields of the passed class, ...super class fields, ...super-super class fields, ...]
+     *
+     * @param clazz the class the go the declared fields from
+     * @return a list of all declared fields of the given class, including super class fields
+     */
     static Collection<Field> getFieldsRecursive(Class<? extends SerializableObject> clazz) {
         var fields = new HashMap<String, Field>();
         do {
diff --git a/src/main/java/jef/model/annotations/Clazz.java b/src/main/java/jef/model/annotations/Clazz.java
index 1590ec7..7d3f261 100644
--- a/src/main/java/jef/model/annotations/Clazz.java
+++ b/src/main/java/jef/model/annotations/Clazz.java
@@ -1,10 +1,12 @@
 package jef.model.annotations;
 
+import java.lang.annotation.Documented;
 import java.lang.annotation.ElementType;
 import java.lang.annotation.Retention;
 import java.lang.annotation.RetentionPolicy;
 import java.lang.annotation.Target;
 
+@Documented
 @Target(ElementType.FIELD)
 @Retention(RetentionPolicy.RUNTIME)
 public @interface Clazz {
diff --git a/src/main/java/jef/model/annotations/Id.java b/src/main/java/jef/model/annotations/Id.java
new file mode 100644
index 0000000..11914f1
--- /dev/null
+++ b/src/main/java/jef/model/annotations/Id.java
@@ -0,0 +1,13 @@
+package jef.model.annotations;
+
+import java.lang.annotation.Documented;
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+@Documented
+@Target({ElementType.FIELD})
+@Retention(RetentionPolicy.RUNTIME)
+public @interface Id {
+}
diff --git a/src/main/java/jef/model/annotations/Index.java b/src/main/java/jef/model/annotations/Index.java
new file mode 100644
index 0000000..84f4f90
--- /dev/null
+++ b/src/main/java/jef/model/annotations/Index.java
@@ -0,0 +1,14 @@
+package jef.model.annotations;
+
+import java.lang.annotation.Documented;
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+@Documented
+@Target({ElementType.FIELD, ElementType.TYPE})
+@Retention(RetentionPolicy.RUNTIME)
+public @interface Index {
+    String[] gettersOrFields() default {};
+}
diff --git a/src/main/java/jef/model/annotations/Key.java b/src/main/java/jef/model/annotations/Key.java
new file mode 100644
index 0000000..432eecf
--- /dev/null
+++ b/src/main/java/jef/model/annotations/Key.java
@@ -0,0 +1,14 @@
+package jef.model.annotations;
+
+import java.lang.annotation.Documented;
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+@Documented
+@Target({ElementType.FIELD, ElementType.TYPE})
+@Retention(RetentionPolicy.RUNTIME)
+public @interface Key {
+    String[] gettersOrFields() default {};
+}
diff --git a/src/main/java/jef/model/annotations/NotNull.java b/src/main/java/jef/model/annotations/NotNull.java
index 0d444f6..ae856b3 100644
--- a/src/main/java/jef/model/annotations/NotNull.java
+++ b/src/main/java/jef/model/annotations/NotNull.java
@@ -1,10 +1,12 @@
 package jef.model.annotations;
 
+import java.lang.annotation.Documented;
 import java.lang.annotation.ElementType;
 import java.lang.annotation.Retention;
 import java.lang.annotation.RetentionPolicy;
 import java.lang.annotation.Target;
 
+@Documented
 @Target(ElementType.FIELD)
 @Retention(RetentionPolicy.RUNTIME)
 public @interface NotNull {
diff --git a/src/main/java/jef/model/annotations/Transient.java b/src/main/java/jef/model/annotations/Transient.java
new file mode 100644
index 0000000..708bf2d
--- /dev/null
+++ b/src/main/java/jef/model/annotations/Transient.java
@@ -0,0 +1,13 @@
+package jef.model.annotations;
+
+import java.lang.annotation.Documented;
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+@Documented
+@Target({ElementType.FIELD})
+@Retention(RetentionPolicy.RUNTIME)
+public @interface Transient {
+}
diff --git a/src/main/java/jef/model/annotations/Unique.java b/src/main/java/jef/model/annotations/Unique.java
new file mode 100644
index 0000000..90392db
--- /dev/null
+++ b/src/main/java/jef/model/annotations/Unique.java
@@ -0,0 +1,14 @@
+package jef.model.annotations;
+
+import java.lang.annotation.Documented;
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+@Documented
+@Target({ElementType.FIELD, ElementType.TYPE})
+@Retention(RetentionPolicy.RUNTIME)
+public @interface Unique {
+    String[] gettersOrFields() default {};
+}
diff --git a/src/main/java/jef/model/annotations/processors/IndexProcessor.java b/src/main/java/jef/model/annotations/processors/IndexProcessor.java
new file mode 100644
index 0000000..a6ae043
--- /dev/null
+++ b/src/main/java/jef/model/annotations/processors/IndexProcessor.java
@@ -0,0 +1,33 @@
+package jef.model.annotations.processors;
+
+import jef.model.DbEntity;
+import jef.model.DbField;
+import jef.model.annotations.Index;
+import jef.model.constraints.IndexConstraint;
+import jef.serializable.SerializableObject;
+
+import java.lang.annotation.Annotation;
+import java.util.List;
+
+public class IndexProcessor extends KeyProcessorBase<IndexConstraint, Index> {
+    public static final IndexProcessor INSTANCE = new IndexProcessor();
+
+    private IndexProcessor() {
+        super(Index.class);
+    }
+
+    @Override
+    protected IndexConstraint initConstraint(DbEntity<? extends SerializableObject> entity, List<DbField<?>> fields) {
+        return new IndexConstraint(entity, fields);
+    }
+
+    @Override
+    protected void addConstraint(IndexConstraint constr) {
+        constr.getEntity().addIndex(constr);
+    }
+
+    @Override
+    protected String[] getGettersOrFields(Annotation annotation) {
+        return ((Index) annotation).gettersOrFields();
+    }
+}
diff --git a/src/main/java/jef/model/annotations/processors/KeyProcessor.java b/src/main/java/jef/model/annotations/processors/KeyProcessor.java
new file mode 100644
index 0000000..f207535
--- /dev/null
+++ b/src/main/java/jef/model/annotations/processors/KeyProcessor.java
@@ -0,0 +1,33 @@
+package jef.model.annotations.processors;
+
+import jef.model.DbEntity;
+import jef.model.DbField;
+import jef.model.annotations.Key;
+import jef.model.constraints.KeyConstraint;
+import jef.serializable.SerializableObject;
+
+import java.lang.annotation.Annotation;
+import java.util.List;
+
+public class KeyProcessor extends KeyProcessorBase<KeyConstraint, Key> {
+    public static final KeyProcessor INSTANCE = new KeyProcessor();
+
+    private KeyProcessor() {
+        super(Key.class);
+    }
+
+    @Override
+    protected KeyConstraint initConstraint(DbEntity<? extends SerializableObject> entity, List<DbField<?>> fields) {
+        return new KeyConstraint(entity, fields);
+    }
+
+    @Override
+    protected void addConstraint(KeyConstraint constr) {
+        constr.getEntity().addKey(constr);
+    }
+
+    @Override
+    protected String[] getGettersOrFields(Annotation annotation) {
+        return ((Key) annotation).gettersOrFields();
+    }
+}
diff --git a/src/main/java/jef/model/annotations/processors/KeyProcessorBase.java b/src/main/java/jef/model/annotations/processors/KeyProcessorBase.java
new file mode 100644
index 0000000..34195af
--- /dev/null
+++ b/src/main/java/jef/model/annotations/processors/KeyProcessorBase.java
@@ -0,0 +1,84 @@
+package jef.model.annotations.processors;
+
+import jef.model.DbEntity;
+import jef.model.DbField;
+import jef.model.ModelBuilder;
+import jef.model.ModelException;
+import jef.serializable.SerializableObject;
+
+import java.lang.annotation.Annotation;
+import java.lang.reflect.Field;
+import java.lang.reflect.Method;
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.List;
+import java.util.Locale;
+
+public abstract class KeyProcessorBase<K, T extends Annotation> implements AnnotationProcessor {
+    private final Class<T> annotationClass;
+
+    protected KeyProcessorBase(Class<T> annotationClass) {
+        this.annotationClass = annotationClass;
+    }
+
+    protected abstract K initConstraint(DbEntity<? extends SerializableObject> entity, List<DbField<?>> fields);
+
+    protected abstract void addConstraint(K constr);
+
+    protected abstract String[] getGettersOrFields(Annotation annotation);
+
+    @Override
+    public void apply(ModelBuilder mb) {
+        for (DbEntity<? extends SerializableObject> entity : mb.getEntities()) {
+            //class annotation
+            var classAnno = entity.getType().getAnnotationsByType(annotationClass);
+            for (T t : classAnno) {
+                var classFields = Arrays.stream(getGettersOrFields(t))
+                        .map(name -> getField(entity, name))
+                        .map(field -> {
+                            var dbfield = (DbField<?>) entity.getField(field);
+                            if (dbfield == null) {
+                                throw new ModelException("DbField with field " + field.getName() + " not found in " + entity.getType().getSimpleName());
+                            }
+                            return dbfield;
+                        }).toList();
+                addConstraint(initConstraint(entity, new ArrayList<>(classFields)));
+            }
+
+            //annotation on fields
+            for (DbField<?> field : entity.getFields()) {
+                if (field.getField() != null && field.getField().getAnnotationsByType(annotationClass).length > 0) {
+                    var dbfield = entity.getField(field.getField());
+                    if (dbfield == null) {
+                        throw new ModelException("DbField with field " + field.getName() + " not found in " + entity.getType().getSimpleName());
+                    }
+                    addConstraint(initConstraint(entity, List.of(dbfield)));
+                }
+            }
+        }
+    }
+
+    private Field getField(DbEntity<? extends SerializableObject> entity, String fieldOrGetter) {
+        Method getter = null;
+        try {
+            getter = entity.getType().getDeclaredMethod(fieldOrGetter);
+        } catch (NoSuchMethodException e) {
+        }
+
+        Field field = null;
+        try {
+            if (getter != null && getter.getName().length() > 3 && getter.getName().startsWith("get")) {
+                var name = getter.getName().substring(3, 4).toLowerCase(Locale.ROOT) + getter.getName().substring(4); //HACK
+                field = entity.getType().getDeclaredField(name);
+            } else {
+                field = entity.getType().getDeclaredField(fieldOrGetter);
+            }
+        } catch (NoSuchFieldException e) {
+        }
+
+        if (field == null) {
+            throw new ModelException("Cannot find getter/field '" + fieldOrGetter + "' in " + entity.getType().getSimpleName());
+        }
+        return field;
+    }
+}
diff --git a/src/main/java/jef/model/annotations/processors/NotNullProcessor.java b/src/main/java/jef/model/annotations/processors/NotNullProcessor.java
index 3cc9994..1a29d3d 100644
--- a/src/main/java/jef/model/annotations/processors/NotNullProcessor.java
+++ b/src/main/java/jef/model/annotations/processors/NotNullProcessor.java
@@ -16,7 +16,7 @@ public class NotNullProcessor implements AnnotationProcessor {
     public void apply(ModelBuilder mb) {
         for (DbEntity<? extends SerializableObject> entity : mb.getEntities()) {
             for (DbField<?> field : entity.getFields()) {
-                if (field.getField().getAnnotationsByType(NotNull.class).length > 0) {
+                if (field.getField() != null && field.getField().getAnnotationsByType(NotNull.class).length > 0) {
                     field.setNotNull(true);
                 }
             }
diff --git a/src/main/java/jef/model/annotations/processors/UniqueProcessor.java b/src/main/java/jef/model/annotations/processors/UniqueProcessor.java
new file mode 100644
index 0000000..cb76b93
--- /dev/null
+++ b/src/main/java/jef/model/annotations/processors/UniqueProcessor.java
@@ -0,0 +1,33 @@
+package jef.model.annotations.processors;
+
+import jef.model.DbEntity;
+import jef.model.DbField;
+import jef.model.annotations.Unique;
+import jef.model.constraints.UniqueConstraint;
+import jef.serializable.SerializableObject;
+
+import java.lang.annotation.Annotation;
+import java.util.List;
+
+public class UniqueProcessor extends KeyProcessorBase<UniqueConstraint, Unique> {
+    public static final UniqueProcessor INSTANCE = new UniqueProcessor();
+
+    private UniqueProcessor() {
+        super(Unique.class);
+    }
+
+    @Override
+    protected UniqueConstraint initConstraint(DbEntity<? extends SerializableObject> entity, List<DbField<?>> fields) {
+        return new UniqueConstraint(entity, fields);
+    }
+
+    @Override
+    protected void addConstraint(UniqueConstraint constr) {
+        constr.getEntity().addUniqueContstraint(constr);
+    }
+
+    @Override
+    protected String[] getGettersOrFields(Annotation annotation) {
+        return ((Unique) annotation).gettersOrFields();
+    }
+}
diff --git a/src/main/java/jef/model/constraints/Constraint.java b/src/main/java/jef/model/constraints/Constraint.java
new file mode 100644
index 0000000..401dd1f
--- /dev/null
+++ b/src/main/java/jef/model/constraints/Constraint.java
@@ -0,0 +1,29 @@
+package jef.model.constraints;
+
+import jef.model.DbEntity;
+import jef.model.DbField;
+
+import java.util.List;
+
+public interface Constraint {
+    /**
+     * Returns the DbEntity containing the constraint.
+     *
+     * @return he DbEntity containing the constraint
+     */
+    DbEntity<?> getEntity();
+
+    /**
+     * Returns the name of the constraint.
+     *
+     * @return the name of the constraint
+     */
+    String getName();
+
+    /**
+     * Returns the fields of {@code getEntity()} involved in this constraint.
+     *
+     * @return the fields of {@code getEntity()} involved in this constraint
+     */
+    List<DbField<?>> getFields();
+}
diff --git a/src/main/java/jef/model/constraints/ForeignKeyConstraint.java b/src/main/java/jef/model/constraints/ForeignKeyConstraint.java
new file mode 100644
index 0000000..761b970
--- /dev/null
+++ b/src/main/java/jef/model/constraints/ForeignKeyConstraint.java
@@ -0,0 +1,23 @@
+package jef.model.constraints;
+
+import jef.model.DbEntity;
+import jef.model.DbField;
+import lombok.AllArgsConstructor;
+import lombok.Getter;
+
+import java.util.List;
+import java.util.stream.Collectors;
+
+@Getter
+@AllArgsConstructor
+public class ForeignKeyConstraint implements Constraint {
+    private final DbEntity<?> entity;
+    private final List<DbField<?>> fields;
+    private final DbEntity<?> referencedEntity;
+    private final List<DbField<?>> referencedFields;
+
+    @Override
+    public String getName() {
+        return "FK_" + entity.getName() + "_" + referencedEntity.getName() + "_" + fields.stream().map(DbField::getName).collect(Collectors.joining("_"));
+    }
+}
diff --git a/src/main/java/jef/model/constraints/IndexConstraint.java b/src/main/java/jef/model/constraints/IndexConstraint.java
new file mode 100644
index 0000000..e9f7803
--- /dev/null
+++ b/src/main/java/jef/model/constraints/IndexConstraint.java
@@ -0,0 +1,21 @@
+package jef.model.constraints;
+
+import jef.model.DbEntity;
+import jef.model.DbField;
+import lombok.AllArgsConstructor;
+import lombok.Getter;
+
+import java.util.List;
+import java.util.stream.Collectors;
+
+@Getter
+@AllArgsConstructor
+public class IndexConstraint implements Constraint {
+    private final DbEntity<?> entity;
+    private final List<DbField<?>> fields;
+
+    @Override
+    public String getName() {
+        return "I_" + entity.getName() + "_" + fields.stream().map(DbField::getName).collect(Collectors.joining("_"));
+    }
+}
diff --git a/src/main/java/jef/model/constraints/KeyConstraint.java b/src/main/java/jef/model/constraints/KeyConstraint.java
new file mode 100644
index 0000000..fc173a2
--- /dev/null
+++ b/src/main/java/jef/model/constraints/KeyConstraint.java
@@ -0,0 +1,21 @@
+package jef.model.constraints;
+
+import jef.model.DbEntity;
+import jef.model.DbField;
+import lombok.AllArgsConstructor;
+import lombok.Getter;
+
+import java.util.List;
+import java.util.stream.Collectors;
+
+@Getter
+@AllArgsConstructor
+public class KeyConstraint implements Constraint {
+    private final DbEntity<?> entity;
+    private final List<DbField<?>> fields;
+
+    @Override
+    public String getName() {
+        return "K_" + entity.getName() + "_" + fields.stream().map(DbField::getName).collect(Collectors.joining("_"));
+    }
+}
diff --git a/src/main/java/jef/model/constraints/PrimaryKeyConstraint.java b/src/main/java/jef/model/constraints/PrimaryKeyConstraint.java
new file mode 100644
index 0000000..81e7fb6
--- /dev/null
+++ b/src/main/java/jef/model/constraints/PrimaryKeyConstraint.java
@@ -0,0 +1,20 @@
+package jef.model.constraints;
+
+import jef.model.DbEntity;
+import jef.model.DbField;
+import lombok.AllArgsConstructor;
+import lombok.Getter;
+
+import java.util.List;
+
+@Getter
+@AllArgsConstructor
+public class PrimaryKeyConstraint implements Constraint {
+    private final DbEntity<?> entity;
+    private final List<DbField<?>> fields;
+
+    @Override
+    public String getName() {
+        return "PRIMARY";
+    }
+}
diff --git a/src/main/java/jef/model/constraints/UniqueConstraint.java b/src/main/java/jef/model/constraints/UniqueConstraint.java
new file mode 100644
index 0000000..40c0e88
--- /dev/null
+++ b/src/main/java/jef/model/constraints/UniqueConstraint.java
@@ -0,0 +1,21 @@
+package jef.model.constraints;
+
+import jef.model.DbEntity;
+import jef.model.DbField;
+import lombok.AllArgsConstructor;
+import lombok.Getter;
+
+import java.util.List;
+import java.util.stream.Collectors;
+
+@Getter
+@AllArgsConstructor
+public class UniqueConstraint implements Constraint {
+    private final DbEntity<?> entity;
+    private final List<DbField<?>> fields;
+
+    @Override
+    public String getName() {
+        return "U_" + entity.getName() + "_" + fields.stream().map(DbField::getName).collect(Collectors.joining("_"));
+    }
+}
diff --git a/src/test/java/jef/model/DbContextTest.java b/src/test/java/jef/model/DbContextTest.java
index 98a519f..4c9c742 100644
--- a/src/test/java/jef/model/DbContextTest.java
+++ b/src/test/java/jef/model/DbContextTest.java
@@ -2,10 +2,13 @@ package jef.model;
 
 import jef.DbSet;
 import jef.model.annotations.Clazz;
+import jef.model.annotations.Id;
 import jef.serializable.SerializableObject;
 import lombok.Getter;
 import org.junit.jupiter.api.Test;
 
+import java.util.List;
+
 import static org.junit.jupiter.api.Assertions.assertEquals;
 import static org.junit.jupiter.api.Assertions.assertFalse;
 import static org.junit.jupiter.api.Assertions.assertThrows;
@@ -14,30 +17,25 @@ import static org.junit.jupiter.api.Assertions.assertTrue;
 class DbContextTest {
 
     @Test
-    public void test() {
-        var mb = ModelBuilder.from(new Ctx());
-        for (DbEntity<? extends SerializableObject> entity : mb.getEntities()) {
-            assertEquals("TestClass", entity.getName());
-            assertEquals(5, entity.getFields().size());
-            assertEquals(1, entity.getFields().stream().filter(e -> e.getName().equals("i")).count());
-            assertEquals(1, entity.getFields().stream().filter(e -> e.getName().equals("d")).count());
-            assertEquals(1, entity.getFields().stream().filter(e -> e.getName().equals("f")).count());
-            assertEquals(1, entity.getFields().stream().filter(e -> e.getName().equals("l")).count());
-            assertEquals(1, entity.getFields().stream().filter(e -> e.getName().equals("o")).count());
+    public void testSimple() {
+        var mb = ModelBuilder.from(Ctx.class);
+        assertEquals(1, mb.getEntities().size());
+        assertEquals(TestClass.class.getSimpleName(), mb.getEntities().get(0).getName());
 
-            //intrinsic non null
-            assertEquals(5, entity.getFields().size());
-            assertTrue(entity.getFields().stream().filter(e -> e.getName().equals("i")).findFirst().get().isNotNull());
-            assertTrue(entity.getFields().stream().filter(e -> e.getName().equals("d")).findFirst().get().isNotNull());
-            assertTrue(entity.getFields().stream().filter(e -> e.getName().equals("f")).findFirst().get().isNotNull());
-            assertTrue(entity.getFields().stream().filter(e -> e.getName().equals("l")).findFirst().get().isNotNull());
-            assertFalse(entity.getFields().stream().filter(e -> e.getName().equals("o")).findFirst().get().isNotNull());
-        }
-    }
+        assertEquals(5, mb.getEntities().get(0).getFields().size());
+        assertEquals(1, mb.getEntities().get(0).getFields().stream().filter(e -> e.getName().equals("i")).count());
+        assertEquals(1, mb.getEntities().get(0).getFields().stream().filter(e -> e.getName().equals("d")).count());
+        assertEquals(1, mb.getEntities().get(0).getFields().stream().filter(e -> e.getName().equals("f")).count());
+        assertEquals(1, mb.getEntities().get(0).getFields().stream().filter(e -> e.getName().equals("l")).count());
+        assertEquals(1, mb.getEntities().get(0).getFields().stream().filter(e -> e.getName().equals("o")).count());
 
-    @Test
-    public void testMissingAnnotation() {
-        assertThrows(ModelException.class, () -> ModelBuilder.from(new CtxMissingAnnotation()));
+        //intrinsic non null
+        assertEquals(5, mb.getEntities().get(0).getFields().size());
+        assertTrue(mb.getEntities().get(0).getFields().stream().filter(e -> e.getName().equals("i")).findFirst().get().isNotNull());
+        assertTrue(mb.getEntities().get(0).getFields().stream().filter(e -> e.getName().equals("d")).findFirst().get().isNotNull());
+        assertTrue(mb.getEntities().get(0).getFields().stream().filter(e -> e.getName().equals("f")).findFirst().get().isNotNull());
+        assertTrue(mb.getEntities().get(0).getFields().stream().filter(e -> e.getName().equals("l")).findFirst().get().isNotNull());
+        assertFalse(mb.getEntities().get(0).getFields().stream().filter(e -> e.getName().equals("o")).findFirst().get().isNotNull());
     }
 
     public static class Ctx extends DbContext {
@@ -46,6 +44,11 @@ class DbContextTest {
         private DbSet<TestClass> objects1;
     }
 
+    @Test
+    public void testMissingAnnotation() {
+        assertThrows(ModelException.class, () -> ModelBuilder.from(CtxMissingAnnotation.class));
+    }
+
     public static class CtxMissingAnnotation extends DbContext {
 
         private DbSet<TestClass> objects1;
@@ -53,10 +56,88 @@ class DbContextTest {
 
     @Getter
     public static class TestClass extends SerializableObject {
+        @Id
         public int i = 1;
         public Object o = new Object();
         public double d;
         public float f;
         public long l;
     }
+
+    //test nested
+    @Test
+    public void testNestedObjectsSimple() {
+        var mb = ModelBuilder.from(CtxNestedSimple.class);
+
+        assertEquals(2, mb.getEntities().size());
+        assertEquals(TestClass2.class.getSimpleName(), mb.getEntities().get(0).getName());
+        assertEquals(TestClass.class.getSimpleName(), mb.getEntities().get(1).getName());
+
+        //TestClass2
+        assertEquals(2, mb.getEntities().get(0).getFields().size());
+        assertEquals(1, mb.getEntities().get(0).getFields().stream().filter(e -> e.getName().equals("i")).count());
+        assertEquals(1, mb.getEntities().get(0).getFields().stream().filter(e -> e.getName().equals("nestedI")).count());
+
+        //TestClass
+        assertEquals(5, mb.getEntities().get(1).getFields().size());
+        assertEquals(1, mb.getEntities().get(1).getFields().stream().filter(e -> e.getName().equals("i")).count());
+        assertEquals(1, mb.getEntities().get(1).getFields().stream().filter(e -> e.getName().equals("d")).count());
+        assertEquals(1, mb.getEntities().get(1).getFields().stream().filter(e -> e.getName().equals("f")).count());
+        assertEquals(1, mb.getEntities().get(1).getFields().stream().filter(e -> e.getName().equals("l")).count());
+        assertEquals(1, mb.getEntities().get(1).getFields().stream().filter(e -> e.getName().equals("o")).count());
+    }
+
+    public static class CtxNestedSimple extends DbContext {
+        @Clazz(clazz = TestClass2.class)
+        private DbSet<TestClass2> objects1;
+    }
+
+    @Getter
+    public static class TestClass2 extends SerializableObject {
+        @Id
+        public int i = 1;
+        @Clazz(clazz = TestClass.class)
+        public List<TestClass> nested;
+    }
+
+    //test nested
+    @Test
+    public void testNestedObjects2Layer() {
+        var mb = ModelBuilder.from(CtxNested2Layer.class);
+
+        assertEquals(3, mb.getEntities().size());
+        assertEquals(TestClass3.class.getSimpleName(), mb.getEntities().get(0).getName());
+        assertEquals(TestClass2.class.getSimpleName(), mb.getEntities().get(1).getName());
+        assertEquals(TestClass.class.getSimpleName(), mb.getEntities().get(2).getName());
+
+        //TestClass2
+        assertEquals(2, mb.getEntities().get(0).getFields().size());
+        assertEquals(1, mb.getEntities().get(0).getFields().stream().filter(e -> e.getName().equals("id")).count());
+        assertEquals(1, mb.getEntities().get(0).getFields().stream().filter(e -> e.getName().equals("nested2I")).count());
+
+        //TestClass2
+        assertEquals(2, mb.getEntities().get(1).getFields().size());
+        assertEquals(1, mb.getEntities().get(1).getFields().stream().filter(e -> e.getName().equals("i")).count());
+        assertEquals(1, mb.getEntities().get(1).getFields().stream().filter(e -> e.getName().equals("nestedI")).count());
+
+        //TestClass
+        assertEquals(5, mb.getEntities().get(2).getFields().size());
+        assertEquals(1, mb.getEntities().get(2).getFields().stream().filter(e -> e.getName().equals("i")).count());
+        assertEquals(1, mb.getEntities().get(2).getFields().stream().filter(e -> e.getName().equals("d")).count());
+        assertEquals(1, mb.getEntities().get(2).getFields().stream().filter(e -> e.getName().equals("f")).count());
+        assertEquals(1, mb.getEntities().get(2).getFields().stream().filter(e -> e.getName().equals("l")).count());
+        assertEquals(1, mb.getEntities().get(2).getFields().stream().filter(e -> e.getName().equals("o")).count());
+    }
+
+    public static class CtxNested2Layer extends DbContext {
+        @Clazz(clazz = TestClass3.class)
+        private DbSet<TestClass3> objects1;
+    }
+
+    @Getter
+    public static class TestClass3 extends SerializableObject {
+        public int id = 1;
+        @Clazz(clazz = TestClass2.class)
+        public List<TestClass2> nested2;
+    }
 }
\ No newline at end of file
diff --git a/src/test/java/jef/model/annotations/processors/IndexProcessorTest.java b/src/test/java/jef/model/annotations/processors/IndexProcessorTest.java
new file mode 100644
index 0000000..05ec609
--- /dev/null
+++ b/src/test/java/jef/model/annotations/processors/IndexProcessorTest.java
@@ -0,0 +1,82 @@
+package jef.model.annotations.processors;
+
+import jef.DbSet;
+import jef.model.DbContext;
+import jef.model.ModelBuilder;
+import jef.model.annotations.Clazz;
+import jef.model.annotations.Index;
+import jef.serializable.SerializableObject;
+import lombok.Getter;
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+class IndexProcessorTest {
+    @Test
+    public void testSimple() {
+        var mb = ModelBuilder.from(Ctx.class);
+
+        assertEquals(1, mb.getEntities().size());
+        assertEquals(TestClass.class.getSimpleName(), mb.getEntities().get(0).getName());
+
+        assertFalse(mb.getEntities().get(0).getFields().stream().filter(e -> e.getName().equals("i")).findFirst().get().isIndex());
+        assertFalse(mb.getEntities().get(0).getFields().stream().filter(e -> e.getName().equals("d")).findFirst().get().isIndex());
+        assertFalse(mb.getEntities().get(0).getFields().stream().filter(e -> e.getName().equals("f")).findFirst().get().isIndex());
+        assertTrue(mb.getEntities().get(0).getFields().stream().filter(e -> e.getName().equals("l")).findFirst().get().isIndex());
+        assertFalse(mb.getEntities().get(0).getFields().stream().filter(e -> e.getName().equals("o")).findFirst().get().isIndex());
+    }
+
+    @Test
+    public void testIndexOnClass() {
+        var mb = ModelBuilder.from(CtxIndexOnClass.class);
+
+        assertEquals(1, mb.getEntities().size());
+        assertEquals(TestClassIndexOnClass.class.getSimpleName(), mb.getEntities().get(0).getName());
+
+        assertFalse(mb.getEntities().get(0).getFields().stream().filter(e -> e.getName().equals("i")).findFirst().get().isIndex());
+        assertTrue(mb.getEntities().get(0).getFields().stream().filter(e -> e.getName().equals("d")).findFirst().get().isIndex());
+        assertFalse(mb.getEntities().get(0).getFields().stream().filter(e -> e.getName().equals("f")).findFirst().get().isIndex());
+        assertFalse(mb.getEntities().get(0).getFields().stream().filter(e -> e.getName().equals("l")).findFirst().get().isIndex());
+        assertFalse(mb.getEntities().get(0).getFields().stream().filter(e -> e.getName().equals("o")).findFirst().get().isIndex());
+
+        assertTrue(mb.getEntities().get(0).getIndexes().stream()
+                .anyMatch(e -> e.getFields().size() == 2
+                        && e.getFields().stream().anyMatch(f -> f.getField().getName().equals("i"))
+                        && e.getFields().stream().anyMatch(f -> f.getField().getName().equals("l"))));
+    }
+
+    public static class Ctx extends DbContext {
+
+        @Clazz(clazz = TestClass.class)
+        private DbSet<TestClass> objects1;
+    }
+
+    @Getter
+    public static class TestClass extends SerializableObject {
+        public int i = 1;
+        public Object o = new Object();
+        public double d;
+        public float f;
+        @Index
+        public long l;
+    }
+
+    public static class CtxIndexOnClass extends DbContext {
+
+        @Clazz(clazz = TestClassIndexOnClass.class)
+        private DbSet<TestClassIndexOnClass> objects1;
+    }
+
+    @Getter
+    @Index(gettersOrFields = {"l", "getI"})
+    public static class TestClassIndexOnClass extends SerializableObject {
+        public int i = 1;
+        public Object o = new Object();
+        @Index
+        public double d;
+        public float f;
+        public long l;
+    }
+}
\ No newline at end of file
diff --git a/src/test/java/jef/model/annotations/processors/KeyProcessorTest.java b/src/test/java/jef/model/annotations/processors/KeyProcessorTest.java
new file mode 100644
index 0000000..58828c8
--- /dev/null
+++ b/src/test/java/jef/model/annotations/processors/KeyProcessorTest.java
@@ -0,0 +1,82 @@
+package jef.model.annotations.processors;
+
+import jef.DbSet;
+import jef.model.DbContext;
+import jef.model.ModelBuilder;
+import jef.model.annotations.Clazz;
+import jef.model.annotations.Key;
+import jef.serializable.SerializableObject;
+import lombok.Getter;
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+class KeyProcessorTest {
+    @Test
+    public void testSimple() {
+        var mb = ModelBuilder.from(Ctx.class);
+
+        assertEquals(1, mb.getEntities().size());
+        assertEquals(TestClass.class.getSimpleName(), mb.getEntities().get(0).getName());
+
+        assertFalse(mb.getEntities().get(0).getFields().stream().filter(e -> e.getName().equals("i")).findFirst().get().isKey());
+        assertFalse(mb.getEntities().get(0).getFields().stream().filter(e -> e.getName().equals("d")).findFirst().get().isKey());
+        assertFalse(mb.getEntities().get(0).getFields().stream().filter(e -> e.getName().equals("f")).findFirst().get().isKey());
+        assertTrue(mb.getEntities().get(0).getFields().stream().filter(e -> e.getName().equals("l")).findFirst().get().isKey());
+        assertFalse(mb.getEntities().get(0).getFields().stream().filter(e -> e.getName().equals("o")).findFirst().get().isKey());
+    }
+
+    @Test
+    public void testKeyOnClass() {
+        var mb = ModelBuilder.from(CtxKeyOnClass.class);
+
+        assertEquals(1, mb.getEntities().size());
+        assertEquals(TestClassKeyOnClass.class.getSimpleName(), mb.getEntities().get(0).getName());
+
+        assertFalse(mb.getEntities().get(0).getFields().stream().filter(e -> e.getName().equals("i")).findFirst().get().isKey());
+        assertTrue(mb.getEntities().get(0).getFields().stream().filter(e -> e.getName().equals("d")).findFirst().get().isKey());
+        assertFalse(mb.getEntities().get(0).getFields().stream().filter(e -> e.getName().equals("f")).findFirst().get().isKey());
+        assertFalse(mb.getEntities().get(0).getFields().stream().filter(e -> e.getName().equals("l")).findFirst().get().isKey());
+        assertFalse(mb.getEntities().get(0).getFields().stream().filter(e -> e.getName().equals("o")).findFirst().get().isKey());
+
+        assertTrue(mb.getEntities().get(0).getKeys().stream()
+                .anyMatch(e -> e.getFields().size() == 2
+                        && e.getFields().stream().anyMatch(f -> f.getField().getName().equals("i"))
+                        && e.getFields().stream().anyMatch(f -> f.getField().getName().equals("l"))));
+    }
+
+    public static class Ctx extends DbContext {
+
+        @Clazz(clazz = TestClass.class)
+        private DbSet<TestClass> objects1;
+    }
+
+    @Getter
+    public static class TestClass extends SerializableObject {
+        public int i = 1;
+        public Object o = new Object();
+        public double d;
+        public float f;
+        @Key
+        public long l;
+    }
+
+    public static class CtxKeyOnClass extends DbContext {
+
+        @Clazz(clazz = TestClassKeyOnClass.class)
+        private DbSet<TestClassKeyOnClass> objects1;
+    }
+
+    @Getter
+    @Key(gettersOrFields = {"l", "getI"})
+    public static class TestClassKeyOnClass extends SerializableObject {
+        public int i = 1;
+        public Object o = new Object();
+        @Key
+        public double d;
+        public float f;
+        public long l;
+    }
+}
\ No newline at end of file
diff --git a/src/test/java/jef/model/annotations/processors/NotNullProcessorTest.java b/src/test/java/jef/model/annotations/processors/NotNullProcessorTest.java
new file mode 100644
index 0000000..b911c21
--- /dev/null
+++ b/src/test/java/jef/model/annotations/processors/NotNullProcessorTest.java
@@ -0,0 +1,51 @@
+package jef.model.annotations.processors;
+
+import jef.DbSet;
+import jef.model.DbContext;
+import jef.model.ModelBuilder;
+import jef.model.annotations.Clazz;
+import jef.model.annotations.NotNull;
+import jef.model.annotations.Unique;
+import jef.serializable.SerializableObject;
+import lombok.Getter;
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+class NotNullProcessorTest {
+
+    @Test
+    public void test() {
+        var mb = ModelBuilder.from(Ctx.class);
+
+        assertEquals(1, mb.getEntities().size());
+        assertEquals(TestClass.class.getSimpleName(), mb.getEntities().get(0).getName());
+
+        assertTrue(mb.getEntities().get(0).getFields().stream().filter(e -> e.getName().equals("i")).findFirst().get().isNotNull());
+        assertTrue(mb.getEntities().get(0).getFields().stream().filter(e -> e.getName().equals("d")).findFirst().get().isNotNull());
+        assertTrue(mb.getEntities().get(0).getFields().stream().filter(e -> e.getName().equals("f")).findFirst().get().isNotNull());
+        assertTrue(mb.getEntities().get(0).getFields().stream().filter(e -> e.getName().equals("l")).findFirst().get().isNotNull());
+        assertFalse(mb.getEntities().get(0).getFields().stream().filter(e -> e.getName().equals("o")).findFirst().get().isNotNull());
+        assertTrue(mb.getEntities().get(0).getFields().stream().filter(e -> e.getName().equals("s")).findFirst().get().isNotNull());
+    }
+
+
+    public static class Ctx extends DbContext {
+
+        @Clazz(clazz = TestClass.class)
+        private DbSet<TestClass> objects1;
+    }
+
+    @Getter
+    public static class TestClass extends SerializableObject {
+        public int i = 1;
+        public Object o = new Object();
+        public double d;
+        public float f;
+        public long l;
+        @NotNull
+        public String s;
+    }
+}
\ No newline at end of file
diff --git a/src/test/java/jef/model/annotations/processors/UniqueProcessorTest.java b/src/test/java/jef/model/annotations/processors/UniqueProcessorTest.java
new file mode 100644
index 0000000..9ee017e
--- /dev/null
+++ b/src/test/java/jef/model/annotations/processors/UniqueProcessorTest.java
@@ -0,0 +1,82 @@
+package jef.model.annotations.processors;
+
+import jef.DbSet;
+import jef.model.DbContext;
+import jef.model.ModelBuilder;
+import jef.model.annotations.Clazz;
+import jef.model.annotations.Unique;
+import jef.serializable.SerializableObject;
+import lombok.Getter;
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+class UniqueProcessorTest {
+    @Test
+    public void testSimple() {
+        var mb = ModelBuilder.from(Ctx.class);
+
+        assertEquals(1, mb.getEntities().size());
+        assertEquals(TestClass.class.getSimpleName(), mb.getEntities().get(0).getName());
+
+        assertFalse(mb.getEntities().get(0).getFields().stream().filter(e -> e.getName().equals("i")).findFirst().get().isUnique());
+        assertFalse(mb.getEntities().get(0).getFields().stream().filter(e -> e.getName().equals("d")).findFirst().get().isUnique());
+        assertFalse(mb.getEntities().get(0).getFields().stream().filter(e -> e.getName().equals("f")).findFirst().get().isUnique());
+        assertTrue(mb.getEntities().get(0).getFields().stream().filter(e -> e.getName().equals("l")).findFirst().get().isUnique());
+        assertFalse(mb.getEntities().get(0).getFields().stream().filter(e -> e.getName().equals("o")).findFirst().get().isUnique());
+    }
+
+    @Test
+    public void testUniqueOnClass() {
+        var mb = ModelBuilder.from(CtxUniqueOnClass.class);
+
+        assertEquals(1, mb.getEntities().size());
+        assertEquals(TestClassUniqueOnClass.class.getSimpleName(), mb.getEntities().get(0).getName());
+
+        assertFalse(mb.getEntities().get(0).getFields().stream().filter(e -> e.getName().equals("i")).findFirst().get().isUnique());
+        assertTrue(mb.getEntities().get(0).getFields().stream().filter(e -> e.getName().equals("d")).findFirst().get().isUnique());
+        assertFalse(mb.getEntities().get(0).getFields().stream().filter(e -> e.getName().equals("f")).findFirst().get().isUnique());
+        assertFalse(mb.getEntities().get(0).getFields().stream().filter(e -> e.getName().equals("l")).findFirst().get().isUnique());
+        assertFalse(mb.getEntities().get(0).getFields().stream().filter(e -> e.getName().equals("o")).findFirst().get().isUnique());
+
+        assertTrue(mb.getEntities().get(0).getUniqueKeys().stream()
+                .anyMatch(e -> e.getFields().size() == 2
+                        && e.getFields().stream().anyMatch(f -> f.getField().getName().equals("i"))
+                        && e.getFields().stream().anyMatch(f -> f.getField().getName().equals("l"))));
+    }
+
+    public static class Ctx extends DbContext {
+
+        @Clazz(clazz = TestClass.class)
+        private DbSet<TestClass> objects1;
+    }
+
+    @Getter
+    public static class TestClass extends SerializableObject {
+        public int i = 1;
+        public Object o = new Object();
+        public double d;
+        public float f;
+        @Unique
+        public long l;
+    }
+
+    public static class CtxUniqueOnClass extends DbContext {
+
+        @Clazz(clazz = TestClassUniqueOnClass.class)
+        private DbSet<TestClassUniqueOnClass> objects1;
+    }
+
+    @Getter
+    @Unique(gettersOrFields = {"l", "getI"})
+    public static class TestClassUniqueOnClass extends SerializableObject {
+        public int i = 1;
+        public Object o = new Object();
+        @Unique
+        public double d;
+        public float f;
+        public long l;
+    }
+}
\ No newline at end of file