Mongodb

1.mongodb新增加字段会不成功，解决方法：

var schema_comment = new mongoose.Schema({
    cid: String,
    content: String,
    createTime: {type: Date, default: Date.now()}
},{
    strict: false   //enable to add new fields dynamic
});

参考：https://github.com/LearnBoost/mongoose/issues/1867