Add attribute.field support for foreign keys

lib/associations/has-many.js

@@ -218,20 +218,24 @@ module.exports = (function() {
       });
 
       // define a new model, which connects the models
-      var sourceKeyType = this.source.rawAttributes[this.source.primaryKeyAttribute].type
-        , targetKeyType = this.target.rawAttributes[this.target.primaryKeyAttribute].type
+      var sourceKey = this.source.rawAttributes[this.source.primaryKeyAttribute]
+        , sourceKeyType = sourceKey.type
+        , sourceKeyField = sourceKey.field || this.source.primaryKeyAttribute
+        , targetKey = this.target.rawAttributes[this.target.primaryKeyAttribute]
+        , targetKeyType = targetKey.type
+        , targetKeyField = targetKey.field || this.target.primaryKeyAttribute
         , sourceAttribute = Utils._.defaults(this.foreignKeyAttribute, { type: sourceKeyType })
         , targetAttribute = Utils._.defaults(this.targetAssociation.foreignKeyAttribute, { type: targetKeyType });
 
       if (this.options.constraints !== false) {
         sourceAttribute.references = this.source.getTableName();
-        sourceAttribute.referencesKey = this.source.primaryKeyAttribute;
+        sourceAttribute.referencesKey = sourceKeyField;
         sourceAttribute.onDelete = this.options.onDelete || 'CASCADE';
         sourceAttribute.onUpdate = this.options.onUpdate || 'CASCADE';
       }
       if (this.targetAssociation.options.constraints !== false) {
         targetAttribute.references = this.target.getTableName();
-        targetAttribute.referencesKey = this.target.primaryKeyAttribute;
+        targetAttribute.referencesKey = targetKeyField;
         targetAttribute.onDelete = this.targetAssociation.options.onDelete || 'CASCADE';
         targetAttribute.onUpdate = this.targetAssociation.options.onUpdate || 'CASCADE';
       }

lib/associations/helpers.js

@@ -16,9 +16,9 @@ module.exports = {
     if (options.foreignKeyConstraint || options.onDelete || options.onUpdate) {
 
       // Find primary keys: composite keys not supported with this approach
-      var primaryKeys = Utils._.filter(Utils._.keys(source.rawAttributes), function(key) {
-        return source.rawAttributes[key].primaryKey;
-      });
+      var primaryKeys = Utils._.chain(source.rawAttributes).keys()
+        .filter(function(key) { return source.rawAttributes[key].primaryKey; })
+        .map(function(key) { return source.rawAttributes[key].field || key; }).value();
 
       if (primaryKeys.length === 1) {
         if (!!source.options.schema) {