Get information if the feed is liked by the user in a single query (Firestore)

Question

I want to show feeds for my users.
Every post has a \"like\" button (like in twitter, Instagram...)
I want to show a different icon if the post is already liked o

Answer 1

You could create an array within each post containing the userID's of the users who liked the post.

// data model

posts/{postID}
  -- content (string)
  -- likes: [
       user123,
       user567,
       user895,
  ]

Then query the posts like so.

db.collection('posts')
  .orderBy('createdAt', 'desc')
  .limit(50)

Then inside the snapshot.

db.collection('posts')
  .orderBy('createdAt', 'desc')
  .limit(50).get()
  .then(snapshot => {
    if (snapshot.empty) {
      console.log('No matching documents.');
      return;
    }  

    snapshot.forEach(doc => {
      console.log(doc.id, '=>', doc.data());

      var liked = false;
      var likes = doc.data().likes;

      if (likes.includes(user_uid){
         liked = true
      }

      return createPost(doc.data(), liked);


    });
  })
  .catch(err => {
    console.log('Error getting documents', err);
  });

Then below create a function called createPost() taking parameters data and likedStatus.

Add {likedStatus ? "You liked this" : "Like post"} into your createPost function.

createPost = (data, likedStatus) => {

  return (
    

       

           {likedStatus ? "You liked this" : "Like post"}
       
    
  

  )

}