drop referencing foreign keys when primary key of entity builder is dropped

src/main/java/jef/model/KeyBuilder.java

@@ -144,11 +144,17 @@ public class KeyBuilder<T extends SerializableObject> {
         isPrimaryKey(true);
     }
 
-    public void isPrimaryKey(boolean primary) {//TODO foreign key integrity
+    public void isPrimaryKey(boolean primary) {
         if (primary) {
             entity.setPrimaryKey(new PrimaryKeyConstraint(entity, fields));
         } else {
             entity.setPrimaryKey(null);
+
+            //drop referencing foreign keys
+            modelBuilder.entities().forEach(e -> {
+                var remove = e.getEntity().getForeignKeys().stream().filter(fk -> fk.getReferencedEntity() == this.entity).toList();
+                remove.forEach(fk -> e.getEntity().dropForeignKey(fk));
+            });
         }
     }
 

src/test/java/jef/model/KeyBuilderPrimaryDropRelatedForeignKeyDropTest.java

@@ -0,0 +1,61 @@
+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 static org.junit.jupiter.api.Assertions.*;
+
+class KeyBuilderPrimaryDropRelatedForeignKeyDropTest {
+
+    @Test
+    public void test() {
+        var mb = ModelBuilder.from(Ctx.class);
+
+        assertEquals(1, mb.getEntity(TestClass3.class).getForeignKeys().size());
+        assertEquals(1, mb.getEntity(TestClass2.class).getForeignKeys().size());
+        assertEquals(0, mb.getEntity(TestClass.class).getForeignKeys().size());
+
+        mb.entity(TestClass.class).hasOne(e -> e.i).isPrimaryKey(false);
+
+        assertEquals(1, mb.getEntity(TestClass3.class).getForeignKeys().size());
+        assertEquals(0, mb.getEntity(TestClass2.class).getForeignKeys().size());
+        assertEquals(0, mb.getEntity(TestClass.class).getForeignKeys().size());
+    }
+
+    public static class Ctx extends DbContext {
+        @Clazz(TestClass.class)
+        private DbSet<TestClass> objects1;
+        @Clazz(TestClass2.class)
+        private DbSet<TestClass2> objects2;
+        @Clazz(TestClass3.class)
+        private DbSet<TestClass2> objects3;
+    }
+
+    @Getter
+    public static class TestClass3 extends SerializableObject {
+        @Id
+        public int i3 = 1;
+        private TestClass2 nested2;
+    }
+
+    @Getter
+    public static class TestClass2 extends SerializableObject {
+        @Id
+        public int i2 = 1;
+        private TestClass nested;
+    }
+
+    @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;
+    }
+}