Mongoose default sorting order

Question

Mongoose default sorting order

Is there a way to specify sorting order on the schema/model level in Mongoose?

I have model Posts, and I always fetch posts ordered by 'createdAt' field. Thus on each query I have to write .sort('-createdAt'). Can I make this order default for this model?

node.js
express
mongoose

Answer 1

There is no way, in Mongoose, directly to define a default sort order on your query.

If you're doing something over and over again though, you might want to abstract this into a function that does it for you:

function findPostsByDate(cb){
    Posts.find({}).sort('-createdAt').exec(cb);
}

Or even something more generic than that:

function findXByDate(model, findCriteria, cb){
    model.find(findCriteria).sort('-createdAt').exec(cb);
}

Answer 2

You can achieve this by creating a static method in your schema definition.

Mongoose documentation for Methods and statics here: http://mongoosejs.com/docs/2.7.x/docs/methods-statics.html

Example

In your schema file:

PostSchema.statics.sortedFind = function sortedFind(query, fields, options cb){
    //First 3 parameters are optional
    if( arguments.length === 1){
        cb = query;
    } else if (arguments.length === 2) {
        cb = fields;
    } else if(arguments.length === 3){
        cb = options;
    }

    this.find(query, fields, options).sort('-createdAt').exec(cb);
}

Then you can use:

var query = {user_id: currentUser.id}; // query example, modify according to your needs
Post.sortedFind(query, function(err, response){ /* Your code goes here */ });

Answer 3

This is how I enforce sortable columns and provide a default sort. I copy this code into each model and just supply the allowSortOn array.

postSchema.pre('find', function (){
    if (typeof this.options.sort !== 'undefined') {
        var allowSortOn = ["_id","createdAt"]  // add other allowable sort columns here
            , propCount = 0;

        for (var prop in this.options.sort)
            if (this.options.sort.hasOwnProperty(prop)) {
                if (allowSortOn.indexOf(prop) === -1) {
                    console.log('Invalid sort column ' + prop);
                    delete this.options.sort[prop];
                } else {
                    propCount++;
                }
            }

        if (propCount === 0) {
            this.options.sort[allowSortOn[1]] = 1;
            console.log('Setting sort column to ' + JSON.stringify(this.options.sort));
        }
    }
})