如何在Mongoose中合并两个集合并使用createdDate对它们进行排序

Question

I am developing application using MEAN.js in which I have two documents as below:

 var RingtoneSchema = new Schema({
      language: {
            label: String,
            code : String
        },
        deliver:{
            type:Boolean,
            default:false
        },
        artists: [RingtoneArtist],
        digital_booklet:{
           title: {
              type: String,
              trim:true

           },
          copyright:{
              type: String,
              trim:true

          }
        }
        title: {
            type: String,
            default: '',
            required: 'Please fill Album title',
            trim: true
        },
        created: {
            type: Date,
            default: Date.now
        }
    });


    var AlbumSchema = new Schema({
      language: {
            label: String,
            code : String
        },
        deliver:{
            type:Boolean,
            default:false
        },
        artists: [artist],
        title: {
            type: String,
            default: '',
            required: 'Please fill Album title',
            trim: true
        },
    created: {
            type: Date,
            default: Date.now
        });

I want to get all the records from both schema and order them by created date to display them in client side. I don't know how to do this using mongoose. Any help will be appreciated.

Answer 1

Mongodb itself is not relational database and any kind of "join" operation is not possible. I see two ways to go:

1. Easy way, but not the best way: If you, say, need to show 30 items on a page you need:
   • Load 30 items from Ringtone, load 30 items from AlbumSchema
   • Put them together in one array
   • Do final sort in memory.

Downside of this approach is you need to load more data into memory than needed and also perform in memory sort manually.

2. A better way. If you need to show data from two collections it can be a good sign to have one collection instead if two. Your two collections schema looks very similar. Later you can use sparse indexes to optimize queries which require only one of two entities.

Implementation details if you pick first way: you can load data from two queries in parallel using async or using promises and do final in memory sort using underscore

Hope this helps!