Mongoose 中的排序无法正常工作

Question

排序不适用于猫鼬，但我不明白这怎么可能，因为我已经搜索了这么多！任何时候我尝试它都不起作用。这是我的代码

Pics.find({}).limit(8).populate('creator').sort("created_at", 1).execFind(function(err, docs){
    console.log(docs);
});

我明白了：

TypeError: Invalid sort() argument. Must be a string or object.
at Query.sort (/Users/n/Proj/feetshot/node_modules/mongoose/lib/query.js:755:11)
at /Users/n/Proj/feetshot/app.js:112:45
at callbacks (/Users/n/Proj/feetshot/node_modules/express/lib/router/index.js:272:11)
at param (/Users/n/Proj/feetshot/node_modules/express/lib/router/index.js:246:11)
at pass (/Users/n/Proj/feetshot/node_modules/express/lib/router/index.js:253:5)
at Router._dispatch (/Users/n/Proj/feetshot/node_modules/express/lib/router/index.js:280:4)
at Object.handle (/Users/n/Proj/feetshot/node_modules/express/lib/router/index.js:45:10)
at Context.next (/Users/n/Proj/feetshot/node_modules/express/node_modules/connect/lib/http.js:204:15)
at Context.<anonymous> (/Users/n/Proj/feetshot/node_modules/passport/lib/passport/context/http/actions.js:64:8)
at SessionStrategy.pass (native)

我怎样才能使排序工作？

这是我的架构：

var PicSchema = new Schema({
creator: { type: Schema.ObjectId, ref: 'Users' }
, body: String
, created_at: { type: Date, default: Date.now }
, link: { type: String, index: { unique: true } }
, twitter_id: { type: String, index: { unique: true } }
, tags: [String]
  , likes: [{ type: Schema.ObjectId, ref: 'Users' }]
   });

Answer 1

根据您的错误消息，您必须使用 Mongoose 3.x，但是您使用的是 2.x sort 方法参数样式。切换到 2.7.0 Mongoose 版本或将排序用法更改为 sort('created_at')。来自 3.x 来源：

/**
* sort
*
* Sets the sort order. Accepts a single parameter, either an object or string.
* If an object is passed values allowed are 'asc', 'desc', 'ascending', 'descending', 1, -1.
* If a string is passed it must be a space delimited list of path names. The sort order of each path is ascending unless the path name is prefixed with `-` which will be treated as descending.
*
* Examples:
*
* // these are equivalent
* query.sort({ field: 'asc', test: -1 });
* query.sort('field -test');
*
* @param {Object|String}
* @api public
*/

Answer 2

尝试

1. 使用字符串更正排序方法调用
2. 在填充之前进行排序。

所以：

Pics.find({}).sort("created_at").limit(8).populate('creator').execFind(function(err, docs){
    console.log(docs);
});