Don't coerce nested objects into Model instances

For queries, this is undesirable. It also affects
loopback-connector-mongodb's ability to perform nested queries (it
expects plain objects to work correctly, and to allow $elemMatch for
example).

lib/dao.js

@@ -21,6 +21,7 @@ var setScopeValuesFromWhere = utils.setScopeValuesFromWhere;
 var mergeQuery = utils.mergeQuery;
 var util = require('util');
 var assert = require('assert');
+var Model = require('./model');
 
 /**
  * Base class for all persistent objects.
@@ -593,6 +594,10 @@ DataAccessObject._coerce = function (where) {
       continue;
     }
 
+    if (DataType.prototype instanceof Model) {
+      continue;
+    }
+
     if (DataType === geo.GeoPoint) {
       // Skip the GeoPoint as the near operator breaks the assumption that
       // an operation has only one property

test/datatype.test.js

@@ -7,13 +7,16 @@ describe('datatypes', function () {
 
   before(function (done) {
     db = getSchema();
+    Nested = db.define('Nested', {});
+    
     Model = db.define('Model', {
       str: String,
       date: Date,
       num: Number,
       bool: Boolean,
       list: {type: [String]},
-      arr: Array
+      arr: Array,
+      nested: Nested
     });
     db.automigrate(function () {
       Model.destroyAll(done);
@@ -114,4 +117,10 @@ describe('datatypes', function () {
       });
     }
   });
+  
+  it('should not coerce nested objects into ModelConstructor types', function() {
+      var coerced = Model._coerce({ nested: { foo: 'bar' } });
+      coerced.nested.constructor.name.should.equal('Object');
+  });
+  
 });