diff --git a/packages/repository-tests/src/crud/create-retrieve.suite.ts b/packages/repository-tests/src/crud/create-retrieve.suite.ts
index ac8706a7e657..c9feb42c1ccf 100644
--- a/packages/repository-tests/src/crud/create-retrieve.suite.ts
+++ b/packages/repository-tests/src/crud/create-retrieve.suite.ts
@@ -12,9 +12,9 @@ import {
   property,
 } from '@loopback/repository';
 import {expect, toJSON} from '@loopback/testlab';
-import {MixedIdType} from '../helpers.repository-tests';
 import {
   deleteAllModelsInDefaultDataSource,
+  MixedIdType,
   withCrudCtx,
 } from '../helpers.repository-tests';
 import {
@@ -89,7 +89,7 @@ export function createRetrieveSuite(
       const pens = await repo.create({name: 'Pens', categoryId: 1});
       const pencils = await repo.create({name: 'Pencils', categoryId: 2});
       const products = await findByForeignKeys(repo, 'categoryId', [1]);
-      expect(products).deepEqual([pens]);
+      expect(toJSON(products)).deepEqual(toJSON([pens]));
       expect(products).to.not.containDeep(pencils);
     });
 
@@ -97,7 +97,7 @@ export function createRetrieveSuite(
       const pens = await repo.create({name: 'Pens', categoryId: 1});
       const pencils = await repo.create({name: 'Pencils', categoryId: 2});
       const products = await findByForeignKeys(repo, 'categoryId', [1, 2]);
-      expect(products).deepEqual([pens, pencils]);
+      expect(toJSON(products)).deepEqual(toJSON([pens, pencils]));
     });
   });
 }
diff --git a/packages/repository-tests/src/crud/nested-model-properties.suite.ts b/packages/repository-tests/src/crud/nested-model-properties.suite.ts
index e6c2d9722d8a..a3fe2a7c0bbb 100644
--- a/packages/repository-tests/src/crud/nested-model-properties.suite.ts
+++ b/packages/repository-tests/src/crud/nested-model-properties.suite.ts
@@ -14,8 +14,8 @@ import {
 import {expect, toJSON} from '@loopback/testlab';
 import {
   deleteAllModelsInDefaultDataSource,
-  withCrudCtx,
   MixedIdType,
+  withCrudCtx,
 } from '../helpers.repository-tests';
 import {
   CrudFeatures,
@@ -91,6 +91,7 @@ export function nestedModelsPropertiesSuite(
       @property({
         id: true,
         generated: true,
+        useDefaultIdType: true,
       })
       id: MixedIdType;
 
diff --git a/packages/repository-tests/src/crud/relations/acceptance/belongs-to.relation.acceptance.ts b/packages/repository-tests/src/crud/relations/acceptance/belongs-to.relation.acceptance.ts
index 0e23888c83d9..278e323b3b8c 100644
--- a/packages/repository-tests/src/crud/relations/acceptance/belongs-to.relation.acceptance.ts
+++ b/packages/repository-tests/src/crud/relations/acceptance/belongs-to.relation.acceptance.ts
@@ -91,7 +91,7 @@ export function belongsToRelationAcceptance(
         description: 'Order that is shipped Tuesday morning',
       });
       const result = await orderRepo.shipment(order.id);
-      expect(result).to.deepEqual(shipment);
+      expect(toJSON(result)).to.deepEqual(toJSON(shipment));
     });
 
     it('returns undefined if the source instance does not have the foreign key', async () => {
diff --git a/packages/repository-tests/src/crud/relations/acceptance/has-many.relation.acceptance.ts b/packages/repository-tests/src/crud/relations/acceptance/has-many.relation.acceptance.ts
index cdca52274d93..f37c32b4b99d 100644
--- a/packages/repository-tests/src/crud/relations/acceptance/has-many.relation.acceptance.ts
+++ b/packages/repository-tests/src/crud/relations/acceptance/has-many.relation.acceptance.ts
@@ -310,7 +310,7 @@ export function hasManyRelationAcceptance(
         });
         const childsParent = await getParentCustomer(child.id);
         expect(_.pick(childsParent, ['id', 'name'])).to.eql(
-          _.pick(parent, ['id', 'name']),
+          toJSON(_.pick(parent, ['id', 'name'])),
         );
       });
 
diff --git a/packages/repository-tests/src/crud/relations/acceptance/multi-relations-inclusion-resolver.relation.acceptance.ts b/packages/repository-tests/src/crud/relations/acceptance/multi-relations-inclusion-resolver.relation.acceptance.ts
index 4bde2b0774ae..126144e94043 100644
--- a/packages/repository-tests/src/crud/relations/acceptance/multi-relations-inclusion-resolver.relation.acceptance.ts
+++ b/packages/repository-tests/src/crud/relations/acceptance/multi-relations-inclusion-resolver.relation.acceptance.ts
@@ -16,6 +16,8 @@ import {
   withCrudCtx,
 } from '../../../helpers.repository-tests';
 import {
+  Address,
+  AddressRepository,
   Customer,
   CustomerRepository,
   Order,
@@ -36,6 +38,7 @@ export function hasManyInclusionResolverAcceptance(
   );
   function suite() {
     before(deleteAllModelsInDefaultDataSource);
+    let addressRepo: AddressRepository;
     let customerRepo: CustomerRepository;
     let orderRepo: OrderRepository;
 
@@ -43,14 +46,18 @@ export function hasManyInclusionResolverAcceptance(
       withCrudCtx(async function setupRepository(ctx: CrudTestContext) {
         // this helper should create the inclusion resolvers and also
         // register inclusion resolvers for us
-        ({customerRepo, orderRepo} = givenBoundCrudRepositories(
+        ({customerRepo, orderRepo, addressRepo} = givenBoundCrudRepositories(
           ctx.dataSource,
           repositoryClass,
           features,
         ));
         expect(customerRepo.orders.inclusionResolver).to.be.Function();
 
-        await ctx.dataSource.automigrate([Customer.name, Order.name]);
+        await ctx.dataSource.automigrate([
+          Customer.name,
+          Order.name,
+          Address.name,
+        ]);
       }),
     );
 
@@ -63,7 +70,14 @@ export function hasManyInclusionResolverAcceptance(
       const parent = await customerRepo.create({name: 'parent'});
       const customer = await customerRepo.create({
         name: 'customer',
-        parentId: parent.id,
+        //parentId: parent.id,
+      });
+      const address = await addressRepo.create({
+        street: '8200 Warden',
+        city: 'Markham',
+        province: 'On',
+        zipcode: '8200',
+        customerId: parent.id,
       });
       const order = await orderRepo.create({
         description: 'an order',
@@ -71,7 +85,7 @@ export function hasManyInclusionResolverAcceptance(
       });
 
       const result = await customerRepo.find({
-        include: [{relation: 'orders'}, {relation: 'customers'}],
+        include: [{relation: 'orders'}, {relation: 'address'}],
       });
       const expected = [
         {
@@ -84,16 +98,11 @@ export function hasManyInclusionResolverAcceptance(
               shipmentInfo: features.emptyValue,
             },
           ],
-          customers: [
-            {
-              ...customer,
-              parentId: parent.id,
-            },
-          ],
+          address: address,
         },
         {
           ...customer,
-          parentId: parent.id, // doesn't have any related models
+          parentId: features.emptyValue, //parent.id, // doesn't have any related models
         },
       ];
       expect(toJSON(result)).to.deepEqual(toJSON(expected));
diff --git a/packages/repository-tests/src/crud/relations/fixtures/models/address.model.ts b/packages/repository-tests/src/crud/relations/fixtures/models/address.model.ts
index fdaa46032580..47524d77e1d0 100644
--- a/packages/repository-tests/src/crud/relations/fixtures/models/address.model.ts
+++ b/packages/repository-tests/src/crud/relations/fixtures/models/address.model.ts
@@ -19,6 +19,7 @@ export class Address extends Entity {
   @property({
     id: true,
     generated: true,
+    useDefaltIdType: true,
   })
   id: MixedIdType;
   @property({
diff --git a/packages/repository-tests/src/crud/relations/fixtures/models/customer.model.ts b/packages/repository-tests/src/crud/relations/fixtures/models/customer.model.ts
index 6d189eb850ff..07b4104f770a 100644
--- a/packages/repository-tests/src/crud/relations/fixtures/models/customer.model.ts
+++ b/packages/repository-tests/src/crud/relations/fixtures/models/customer.model.ts
@@ -24,6 +24,7 @@ export class Customer extends Entity {
   @property({
     id: true,
     generated: true,
+    useDefaltIdType: true,
   })
   id: MixedIdType;
 
diff --git a/packages/repository-tests/src/crud/relations/fixtures/models/order.model.ts b/packages/repository-tests/src/crud/relations/fixtures/models/order.model.ts
index 226b1fb4fb1a..b1045586a200 100644
--- a/packages/repository-tests/src/crud/relations/fixtures/models/order.model.ts
+++ b/packages/repository-tests/src/crud/relations/fixtures/models/order.model.ts
@@ -20,6 +20,7 @@ export class Order extends Entity {
   @property({
     id: true,
     generated: true,
+    useDefaultIdType: true,
   })
   id: MixedIdType;
 
diff --git a/packages/repository-tests/src/crud/relations/fixtures/models/shipment.model.ts b/packages/repository-tests/src/crud/relations/fixtures/models/shipment.model.ts
index 2005226e7714..d5559aecc3a4 100644
--- a/packages/repository-tests/src/crud/relations/fixtures/models/shipment.model.ts
+++ b/packages/repository-tests/src/crud/relations/fixtures/models/shipment.model.ts
@@ -19,6 +19,7 @@ export class Shipment extends Entity {
   @property({
     id: true,
     generated: true,
+    useDefaltIdType: true,
   })
   id: MixedIdType;
 
diff --git a/packages/repository-tests/src/crud/replace-by-id.suite.ts b/packages/repository-tests/src/crud/replace-by-id.suite.ts
index 2af747b9649c..ddbbe3f7857a 100644
--- a/packages/repository-tests/src/crud/replace-by-id.suite.ts
+++ b/packages/repository-tests/src/crud/replace-by-id.suite.ts
@@ -35,6 +35,7 @@ export function createSuiteForReplaceById(
       type: features.idType,
       id: true,
       generated: true,
+      useDefaultIdType: true,
       description: 'The unique identifier for a product',
     })
     id: MixedIdType;
diff --git a/packages/repository/src/__tests__/unit/decorator/model-and-relation.decorator.unit.ts b/packages/repository/src/__tests__/unit/decorator/model-and-relation.decorator.unit.ts
index bcd60a86dcf7..19d3b307c97b 100644
--- a/packages/repository/src/__tests__/unit/decorator/model-and-relation.decorator.unit.ts
+++ b/packages/repository/src/__tests__/unit/decorator/model-and-relation.decorator.unit.ts
@@ -192,7 +192,12 @@ describe('model decorator', () => {
         column: 'QTY',
       },
     });
-    expect(meta.id).to.eql({type: 'string', id: true, generated: true});
+    expect(meta.id).to.eql({
+      type: 'string',
+      id: true,
+      generated: true,
+      useDefaultIdType: false,
+    });
     expect(meta.isShipped).to.eql({type: Boolean});
   });
 
diff --git a/packages/repository/src/model.ts b/packages/repository/src/model.ts
index e6009c101ef7..6663a8bbb6a3 100644
--- a/packages/repository/src/model.ts
+++ b/packages/repository/src/model.ts
@@ -106,6 +106,16 @@ export class ModelDefinition {
     const definition = (definitionOrType as PropertyDefinition).type
       ? (definitionOrType as PropertyDefinition)
       : {type: definitionOrType};
+
+    if (
+      definition.id === true &&
+      definition.generated === true &&
+      definition.type !== undefined &&
+      definition.useDefaultIdType === undefined
+    ) {
+      definition.useDefaultIdType = false;
+    }
+
     this.properties[name] = definition;
     return this;
   }