Avoid rails making extra queries json include statements by using join

Question

Right now i am getting the 25 most recent posts

posts = Post.where(public: true).limit(25).order(created_at: :desc)

and when i am rendering it i use an include

render :json => posts.as_json(:include => [:user])

this is to get the user who made the post and send it ie:

{
      "id": 43,
      "title": "asdfasdfs",
      "story": "adfaf sdf sd asdf sdf asdf saf adf",
      "created_at": "2017-05-10T22:40:54.587Z",
      "user": {
        "id": 4,
        "first_name": "heelo",
        "last_name": "heelo",
}

which looks like it works great but when looking in the console. its making 26 queries, one to get the posts,

 SELECT  "posts".* FROM "posts" WHERE (public = true) ORDER BY "posts"."created_at" DESC LIMIT ?  [["LIMIT", 25]]

and 25 more to get the user for each post

 SELECT  "users".* FROM "users" WHERE "users"."id" = ? LIMIT ?  [["id", XXX], ["LIMIT", 1]]

to gets its user. Isnt there some way i can do a join to avoid making 25 more queries. i tried

posts = Post.joins(:user).where(public: true).limit(25).order(created_at: :desc)

but it doesnt seem to do anything. Any advice?

Ivan Arambula · Accepted Answer · 2017-05-11 00:52:15Z

1

Try using includes to cut it down to only two queries.

posts = Post.includes(:user).where(public: true).limit(25).order(created_at: :desc)

This will query the last 25 posts in one query and all the associated users in another query.

answered May 11, 2017 at 0:52

Ivan Arambula

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