diff --git a/lib/relation-definition.js b/lib/relation-definition.js
index 3185a6a4..3a5b7371 100644
--- a/lib/relation-definition.js
+++ b/lib/relation-definition.js
@@ -391,13 +391,13 @@ util.inherits(HasOne, Relation);
  * EmbedsOne subclass
  * @param {RelationDefinition|Object} definition
  * @param {Object} modelInstance
- * @returns {EmbedsMany}
+ * @returns {EmbedsOne}
  * @constructor
  * @class EmbedsOne
  */
 function EmbedsOne(definition, modelInstance) {
   if (!(this instanceof EmbedsOne)) {
-    return new EmbedsMany(definition, modelInstance);
+    return new EmbedsOne(definition, modelInstance);
   }
   assert(definition.type === RelationTypes.embedsOne);
   Relation.apply(this, arguments);
@@ -503,9 +503,9 @@ function lookupModelTo(modelFrom, modelTo, params, singularize) {
  * @param {Object|String} params Name of the polymorphic relation or params
  * @returns {Object} The normalized parameters
  */
-function polymorphicParams(params) {
+function polymorphicParams(params, as) {
   if (typeof params === 'string') params = { as: params };
-  if (typeof params.as !== 'string') params.as = 'reference'; // default
+  if (typeof params.as !== 'string') params.as = as || 'reference'; // default
   params.foreignKey = params.foreignKey || i8n.camelize(params.as + '_id', true);
   params.discriminator = params.discriminator || i8n.camelize(params.as + '_type', true);
   return params;
@@ -1079,21 +1079,23 @@ RelationDefinition.belongsTo = function (modelFrom, modelTo, params) {
 
   var idName, relationName, fk;
   if (params.polymorphic) {
+    relationName = params.as || (typeof modelTo === 'string' ? modelTo : null); // initially
+    
     if (params.polymorphic === true) {
       // modelTo arg will be the name of the polymorphic relation (string)
-      polymorphic = polymorphicParams(modelTo);
+      polymorphic = polymorphicParams(modelTo, relationName);
     } else {
-      polymorphic = polymorphicParams(params.polymorphic);
+      polymorphic = polymorphicParams(params.polymorphic, relationName);
     }
     
     modelTo = null; // will lookup dynamically
     
     idName = params.idName || 'id';
-    relationName = params.as || polymorphic.as;
+    relationName = params.as || polymorphic.as; // finally
     fk = polymorphic.foreignKey;
     discriminator = polymorphic.discriminator;
     
-    if (typeof polymorphic.idType === 'string') { // explicit key type
+    if (polymorphic.idType) { // explicit key type
       modelFrom.dataSource.defineProperty(modelFrom.modelName, fk, { type: polymorphic.idType, index: true });
     } else { // try to use the same foreign key type as modelFrom
       modelFrom.dataSource.defineForeignKey(modelFrom.modelName, fk, modelFrom.modelName);
@@ -2208,10 +2210,7 @@ EmbedsMany.prototype.build = function(targetModelData) {
   
   var assignId = (forceId || targetModelData[pk] === undefined);
   
-  if (assignId && typeof connector.generateId === 'function') {
-    var id = connector.generateId(modelTo.modelName, targetModelData, pk);
-    targetModelData[pk] = id;
-  } else if (assignId && pkType === Number) {
+  if (assignId && pkType === Number) {
     var ids = embeddedList.map(function(m) { 
       return (typeof m[pk] === 'number' ? m[pk] : 0);
     });
@@ -2220,6 +2219,9 @@ EmbedsMany.prototype.build = function(targetModelData) {
     } else {
       targetModelData[pk] = 1;
     }
+  } else if (assignId && typeof connector.generateId === 'function') {
+      var id = connector.generateId(modelTo.modelName, targetModelData, pk);
+      targetModelData[pk] = id;
   }
   
   this.definition.applyProperties(modelInstance, targetModelData);
diff --git a/test/relations.test.js b/test/relations.test.js
index 89607fc7..b99f31ba 100644
--- a/test/relations.test.js
+++ b/test/relations.test.js
@@ -1,5 +1,7 @@
 // This test written in mocha+should.js
 var should = require('./init.js');
+var jdb = require('../');
+var DataSource = jdb.DataSource;
 
 var db, tmp, Book, Chapter, Author, Reader;
 var Category, Job;
@@ -7,6 +9,10 @@ var Picture, PictureLink;
 var Person, Address;
 var Link;
 
+var getTransientDataSource = function(settings) {
+    return new DataSource('transient', settings, db.modelBuilder);
+};
+
 describe('relations', function () {
 
   describe('hasMany', function () {
@@ -1679,7 +1685,7 @@ describe('relations', function () {
     var Other;
     
     before(function () {
-      tmp = getSchema('transient');
+      tmp = getTransientDataSource();
       db = getSchema();
       Person = db.define('Person', {name: String});
       Passport = tmp.define('Passport',
@@ -1828,7 +1834,7 @@ describe('relations', function () {
     var address1, address2;
     
     before(function (done) {
-      tmp = getSchema('transient', {defaultIdType: Number});
+      tmp = getTransientDataSource({defaultIdType: Number});
       db = getSchema();
       Person = db.define('Person', {name: String});
       Address = tmp.define('Address', {street: String});
@@ -2008,7 +2014,7 @@ describe('relations', function () {
   
   describe('embedsMany - explicit ids', function () {
     before(function (done) {
-      tmp = getSchema('transient');
+      tmp = getTransientDataSource();
       db = getSchema();
       Person = db.define('Person', {name: String});
       Address = tmp.define('Address', {street: String});
@@ -2415,11 +2421,16 @@ describe('relations', function () {
     
     before(function (done) {
       db = getSchema();
+      tmp = getTransientDataSource();
+      
       Book = db.define('Book', {name: String});
       Author = db.define('Author', {name: String});
       Reader = db.define('Reader', {name: String});
       
-      Link = db.define('Link', {name: String, notes: String}); // generic model
+      Link = tmp.define('Link', {
+        id: {type: Number, id: true},
+        name: String, notes: String
+      }); // generic model
       Link.validatesPresenceOf('linkedId');
       Link.validatesPresenceOf('linkedType');
 
@@ -2433,13 +2444,15 @@ describe('relations', function () {
     });
 
     it('can be declared', function (done) {
+      var idType = db.connector.getDefaultIdType();
+      
       Book.embedsMany(Link, { as: 'people',
         polymorphic: 'linked',
         scope: { include: 'linked' }
       });      
       Link.belongsTo('linked', {
-        polymorphic: true, // needs unique auto-id
-        properties: { name: 'name' }, // denormalized
+        polymorphic: { idType: idType },  // native type
+        properties: { name: 'name' },     // denormalized
         options: { invertProperties: true }
       });
       db.automigrate(done);
diff --git a/test/transient.test.js b/test/transient.test.js
index ec713a9c..e3a03f96 100644
--- a/test/transient.test.js
+++ b/test/transient.test.js
@@ -6,10 +6,14 @@ var should = require('./init.js');
 
 var db, TransientModel, Person, Widget, Item;
 
+var getTransientDataSource = function(settings) {
+    return new DataSource('transient', settings);
+};
+
 describe('Transient connector', function () {
   
   before(function () {
-    db = getSchema('transient');
+    db = getTransientDataSource();
     TransientModel = db.define('TransientModel', {}, { idInjection: false });
     
     Person = TransientModel.extend('Person', {name: String});