fix issue with many-to-many through with custom column names not being mapped correctly

Author: particlebanana

lib/waterline/model/lib/associationMethods/add.js

@@ -290,11 +290,12 @@ Add.prototype.createManyToMany = function(collection, attribute, pk, key, cb) {
 
   // Grab the associated collection's primaryKey
   var collectionAttributes = this.collection.waterline.schema[attribute.collection.toLowerCase()];
-  var associationKey = collectionAttributes.attributes[attribute.on].via;
+  var associationKeyAttr = collectionAttributes.attributes[attribute.on] || collectionAttributes.attributes[attribute.via];
+  var associationKey = associationKeyAttr.via;
 
   // If this is a throughTable, look into the meta data cache for what key to use
   if (collectionAttributes.throughTable) {
-    var cacheKey = collectionAttributes.throughTable[attribute.on + '.' + key];
+    var cacheKey = collectionAttributes.throughTable[attribute.on + '.' + key] || collectionAttributes.throughTable[attribute.via + '.' + key];
     if (!cacheKey) {
       return cb(new Error('Unable to find the proper cache key in the through table definition'));
     }

lib/waterline/model/lib/associationMethods/remove.js

@@ -228,11 +228,12 @@ Remove.prototype.removeManyToMany = function(collection, attribute, pk, key, cb)
 
   // Grab the associated collection's primaryKey
   var collectionAttributes = this.collection.waterline.schema[attribute.collection.toLowerCase()];
-  var associationKey = collectionAttributes.attributes[attribute.on].via;
+  var associationKeyAttr = collectionAttributes.attributes[attribute.on] || collectionAttributes.attributes[attribute.via];
+  var associationKey = associationKeyAttr.via;
 
   // If this is a throughTable, look into the meta data cache for what key to use
   if (collectionAttributes.throughTable) {
-    var cacheKey = collectionAttributes.throughTable[attribute.on + '.' + key];
+    var cacheKey = collectionAttributes.throughTable[attribute.on + '.' + key] || collectionAttributes.throughTable[attribute.via + '.' + key];
     if (!cacheKey) {
       return cb(new Error('Unable to find the proper cache key in the through table definition'));
     }