Fix generated string id's

Co-authored-by: Miroslav Bajtoš <mbajtoss@gmail.com>

lib/datasource.js

@@ -719,7 +719,7 @@ DataSource.prototype.setupDataAccess = function(modelClass, settings) {
     // Check if the id property should be generated
     const idName = modelClass.definition.idName();
     const idProp = modelClass.definition.rawProperties[idName];
-    if (idProp && idProp.generated && this.connector.getDefaultIdType) {
+    if (idProp && idProp.generated && idProp.useDefaultIdType !== false && this.connector.getDefaultIdType) {
       // Set the default id type from connector's ability
       const idType = this.connector.getDefaultIdType() || String;
       idProp.type = idType;

test/loopback-dl.test.js

@@ -648,6 +648,16 @@ describe('DataSource define model', function() {
     done();
   });
 
+  it('injects id with useDefaultIdType to false', function(done) {
+    const ds = new ModelBuilder();
+
+    const User = ds.define('User', {id: {type: String, generated: true, id: true, useDefaultIdType: false}});
+    assert.deepEqual(User.definition.properties.id,
+      {type: String, id: true, generated: true, updateOnly: true, useDefaultIdType: false});
+
+    done();
+  });
+
   it('disables idInjection if the value is false', function(done) {
     const ds = new ModelBuilder();
 

test/manipulation.test.js

@@ -2662,6 +2662,41 @@ describe('manipulation', function() {
         null, // databases representing `undefined` as `null` (e.g. SQL)
       ]);
     });
+
+    it('preserves custom type of auto-generated id property', async () => {
+      // NOTE: This test is trying to reproduce the behavior observed
+      // when using property defined as follows:
+      //  {type: 'string', generated: true, mongodb: {dataType: 'ObjectID'}}
+      // We want to test that behavior for all connectors, which is tricky,
+      // because not all connectors support autogenerated string PK values.
+
+      const User = db.define('UserWithStringId', {
+        id: {
+          type: String,
+          id: true,
+          useDefaultIdType: false,
+          // `useDefaultIdType` is applied only when `generated: true`
+          generated: true,
+        },
+        name: String,
+      }, {forceId: false});
+
+      // disable `generated: true` because many SQL databases cannot
+      // auto-generate string ids
+      User.definition.properties.id.generated = false;
+      User.definition.rawProperties.id.generated = false;
+      await db.automigrate(User.modelName);
+
+      const userId = 'custom user id';
+
+      const createdUser = await User.create({id: userId, name: 'testUser'});
+      // strict equality check
+      createdUser.id.should.equal(userId);
+
+      const foundUser = await User.findById(userId);
+      // strict equality check
+      foundUser.id.should.equal(userId);
+    });
   });
 });