add sum() finder functionality to DAOFactory

lib/dao-factory.js

@@ -620,6 +620,14 @@ module.exports = (function() {
     return this.aggregate(field, 'min', options)
     return this.aggregate(field, 'min', options)
   }
   }
 
 
+  DAOFactory.prototype.sum = function(field, options) {
+    options = Utils._.extend({ attributes: [] }, options || {})
+    options.attributes.push(['sum(' + this.QueryInterface.QueryGenerator.quoteIdentifier(field) + ')', 'sum'])
+    options.parseFloat = true
+
+    return this.QueryInterface.rawSelect(this.getTableName(), options, 'sum')
+  }
+
   DAOFactory.prototype.build = function(values, options) {
   DAOFactory.prototype.build = function(values, options) {
     options = options || { isNewRecord: true, isDirty: true }
     options = options || { isNewRecord: true, isDirty: true }