ndoejs+mongodb 开发2：去重

/**auother : zhz
* 去重复查询condition:查询条件，field:去重复列，查询结果（注意：返回结果只有一列，就是field列，也是选择的去重复选项列）
*/
HelperMongo.prototype.mgDistict = function(collectionName, condition,fields,callback) {
var self = this;
var reqId = _reqId++;
_log(reqId,"开始查找数量... "+collectionName+","+JSON.stringify(condition));
if(fields == null){
return;
}
var field = fields['field'];
function process(callback) {
_getCollection(self, collectionName, function (collection) {
collection.distinct(field,condition,function (error, rst) {
if (error) {
global.err(collectionName + " : " + JSON.stringify(error));
return;
}
_log(reqId, "查找成功--> " + JSON.stringify(rst));
if(callback != undefined) callback(rst);
});
});
}
return _judgePromise(process,callback);
};