How to write mongoose query to combine data from two model's?

Question

Technology: MongoDB, ExpressJS

I have 3 schema

1. userSchema:

userSchema = {
  name: {type: String},
  password: {type: String},
  email: {type: String},
  friends: {type: [mongoose.Types.ObjectId]}
}

2. textPostSchema =

textPostSchema = {
   text: {type: String},
   postType: {type: String, default: "textPost"},
   userId: {type: mongoose.Types.ObjectId}
}

3. articalPostSchema:

articalPostSchema = {
  title: {type: String},
  content: {type: String}
  postType: {type: String, default: "articalPost"},
  userId: {type: mongoose.Types.ObjectId}
}

now I have one social media application in which I have to show these two post when user's friend post's a post, and include infinite scroll. Both textPost and articalPost should be send if to frontend and only total 10 post should be sent at a time. How should I write a API for timeline?

output should look like:

{
  post: [
          {
           title: "artical Post title", 
           content: "artical post content", 
           postType: "articalPost", 
           userId: "60b9c9801a2a2547de643ccd"
          },
          {
           text: "text post ", 
           postType: "textPost", 
           userId: "60b9c9801a2a2547de643ccd"
          }, 
          ... 8 more
        ]
}

UPDATE: I got the solution:- I created on more schema:

timelineSchema = {
    postId: {
      type: mongoose.Types.ObjectId,
      required: true,
      ref: function () {
        switch (this.postCategoryType) {
          case 'articleposts':
            return 'ArticlePost';
          case 'textposts':
            return 'TextPost';
        }
      },
    },
    postCategoryType: {
      type: String,
      required: true,
    },
    userId: {
      type: mongoose.Types.ObjectId,
      required: true,
      ref: 'User',
    },
  },

and then I created one function to get only friends post:

exports.getTimelinePosts = async (req, res) => {
  try {
    const timelinePosts = await TimelineModel.find({
      userId: { $in: [...req.user.friends, req.params.id] },
    })
      .skip((req.params.page - 1) * 10)
      .limit(10)
      .sort({ createdAt: -1 })
      .populate('postId');
    return res.status(200).json({ status: 'success', data: timelinePosts });
  } catch (error) {
    return res.status(500).json(error);
  }
};

Answer 1

Assuming you are using express and mongoose. The code to fetch both,

// first bring all those schema from your mongoose models
const Article = require('./models/ArticleSchema');
const Text = require('./models/TextSchema');

const fetchArticleAndTextPost = async (req, res)=>{
    //find all data 
    const articles = await Article.find();
    const texts = await Text.find();

    //join them together
    const post = articles.concat(texts);

    return res.status(200).json({
        status: 200,
        data: post,
    })

}

Answer 2

To implement the pagination with Mongoose, You can do something like that.

const getPosts = async (userId, pageNumber) => {
  let result = await Post.find({ userId })
    .skip((pageNumber - 1) * 10)
    .limit(10);

  return result;
};

pageNumber is a counter that you need to pass from the frontend and will be incremented by 1 whenever a user hits the scroll limit.

If you want to query and merge data from multiple collections you need to update your schema to use populate . Just include ref where you are referring to other collections.

This may help. https://mongoosejs.com/docs/populate.html