Rendering JSON for multiple Rails objects

Question

This might be a terribly simple question, but this is just something I noticed that is bothering me.

I'm trying to render JSON from one of my controller's methods, but it's giving me a "undefined method `new' for nil:NilClass" error.

Here's the code that's causing the problem:

def index
    @users = User.all
    render json: @users
end

I noticed that when I try to render only one object to JSON, everything works fine:

def show
    @user = User.find(params[:id])
    render json: @user
end

Or when I call to_json on the @users object:

def index
    @users = User.all
    render json: @users.to_json
end

I was under the impression that calling render json: was implicitly calling to_json anyway, so why would calling that twice solve my issue?

I suppose this is because the response has to be the only one json object, not many :) — K.M.
– K.M., Commented Jun 13, 2015 at 8:34
Your code looks reasonable. Can you post the rest of the undefined method new stack trace? — Kristján
– Kristján, Commented Jun 13, 2015 at 16:23
@rubchick that's what I was thinking, but I was just a little confused as to why render json: wouldn't automatically take the array. — sulimmesh
– sulimmesh, Commented Jun 13, 2015 at 19:31

Arslan Ali · Accepted Answer · 2015-06-18 11:07:20Z

1

I believe that it's an issue with @users being an array of objects that needs each object to be converted first before the whole array is reassembled and output as JSON.

edited Jun 18, 2015 at 11:07

Arslan Ali

17.9k9 gold badges64 silver badges84 bronze badges

answered Jun 13, 2015 at 19:32

letsgoduke

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