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Returning HTTP Status Codes in a Rails API

2:14 with Naomi Freeman

As we've been doing through and implementing our API responses, we've introduced a common but subtle mistake in how we send back status codes. In this video, we're going to fix it.

Code Samples

Here is a small snippet in our create method:

def create
  list = TodoList.new(list_params)
  if list.save
    render json: {
      status: 200,
      message: "Successfully created todo list.",
      todo_list: list
    }.to_json
  end
end

We fix it to properly return the correct status code by moving the status key to be an argument to the render method rather than a hash key in the json argument:

  render status: 200, json: {
    message: "Successfully created todo list.",
    todo_list: list
  }.to_json

We then apply this to the rest of the controller actions.

Useful Links

  • 0:00

    As we've been going along coding our API responses,

  • 0:03

    we've accidentally introduced one of the most common errors when creating an API.

  • 0:07

    If we look at our code for each of the responses, we're returning a JSON object

  • 0:11

    with a status key and the corresponding HTTP status code that we want.

  • 0:16

    While it isn't necessarily a problem to send along a status code

  • 0:19

    as part of our API, let's take a look at the response.

  • 0:24

    Notice the very first line.

  • 0:27

    The HTTP response is a 200 OK status when in fact we wanted it to have a 500 status.

  • 0:34

    Luckily, this is an easy fix.

  • 0:37

    We'll move the status key out of the response object.

  • 0:41

    [BLANK_AUDIO]

  • 0:44

    And instead, put it as a argument to the render method.

  • 0:49

    Now if we redo the cURL request, we get the proper response.

  • 0:54

    Well, it's almost the proper response.

  • 0:56

    A 500 error means that the server had some kind of internal error.

  • 1:00

    However, the server, our Rails app, is just fine.

  • 1:04

    It's actually the data that isn't correct for what we're doing.

  • 1:08

    If we look at the HTTP standards, it looks like the status code,

  • 1:13

    422, Unprocessable Entity, is more appropriate and

  • 1:17

    is also the status most preferred by Rails.

  • 1:20

    Other acceptable codes would be 406, which stands for Not Acceptable, and 403,

  • 1:25

    Forbidden, which says that the server understood the request but

  • 1:28

    is refusing to fulfill it.

  • 1:31

    There's some debate over whether or not 400 Bad Request is acceptable, and

  • 1:35

    it's up to you which you choose for your API.

  • 1:38

    We're going to use 422, Unprocessable Entity, for ours.

  • 1:43

    Now when we perform the cURL request again, we get the correct status code.

  • 1:51

    One last thing, we'll go back and fix this for the successful status code as well.

  • 1:57

    Now we just have to go back and fix the rest of our methods.

  • 2:00

    [BLANK_AUDIO]

  • 2:05

    Now I've gone through and fixed all of the status codes.

  • 2:09

    Now your code should look something like this.

  • 2:13

    Perfect

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