Rails Ember strong parameters clarification

Question

What should the strong parameters for my chapters_controller be if I have a Book entity and a Chapter entity?

Note: I am using JSON API.

In my chapters_controller, should my strong parameters be:

:title, :order, :content, :published, :book, :picture

Or should it be:

:title, :order, :content, :published, :book_id, :picture

If I use :book instead of :book_id, then in my Ember application, when I go to create a new chapter, I am able to create it and associate this chapter to the parent book, however, my test fails:

def setup
  @book = books(:one)

  @new_chapter = {
    title: "Cooked Wolf Dinner",
    order: 4,
    published: false,
    content: "The bad wolf was very mad. He was determined to eat the little pig so he climbed down the chimney.",
    book: @book
  }
end

def format_jsonapi(params)
  params = {
    data: {
      type: "books",
      attributes: params
    }
  }
  return params
end

...

test "chapter create - should create new chapter assigned to an existing book" do
  assert_difference "Chapter.count", +1 do
    post chapters_path, params: format_jsonapi(@new_chapter), headers: user_authenticated_header(@jim)
    assert_response :created

    json = JSON.parse(response.body)

    attributes = json['data']['attributes']

    assert_equal "Cooked Wolf Dinner", attributes['title']
    assert_equal 4, attributes['order']
    assert_equal false, attributes['published']
    assert_equal @book.title, attributes['book']['title']
  end
end

I get error in my console saying Association type mismatch.

Perhaps my line:

book: @book 

is causing it?

Either way, gut feeling is telling me I should be using :book in my chapters_controller strong parameters.

It's just my test isn't passing, and I am not sure how to write the parameter hash for my test to pass.

Answer 1

After a few more hours of struggle and looking at the JSON API docs:

http://jsonapi.org/format/#crud-creating

It has come to my attention, in order to set a belongsTo relationship to an entity with JSON API, we need do this:

POST /photos HTTP/1.1
Content-Type: application/vnd.api+json
Accept: application/vnd.api+json

{
  "data": {
    "type": "photos",
    "attributes": {
      "title": "Ember Hamster",
      "src": "http://example.com/images/productivity.png"
    },
    "relationships": {
      "photographer": {
        "data": { "type": "people", "id": "9" }
      }
    }
  }
}

This also led me to fixing another problem I had in the past which I couldn't fix. Books can be created with multiple genres.

The JSON API structure for assigning an array of Genre to a Book entity, we replace the data hash with a data array in the relationship part like this:

"data": [
    { "type": "comments", "id": "5" },
    { "type": "comments", "id": "12" }
]

Additonally, in my controllers, anything strong parameters like so:

:title, :content, genre_ids: []

Becomes

:title, :content, :genres

To comply with JSON API.

So for my new test sample datas I now have:

def setup
  ...
  @new_chapter = {
    title: "Cooked Wolf Dinner",
    order: 4,
    published: false,
    content: "The bad wolf was very mad. He was determined to eat the little pig so he climbed down the chimney.",
  }
  ...
end

def format_jsonapi(params, book_id = nil)
  params = {
    data: {
      type: "chapters",
      attributes: params
    }
  }

  if book_id != nil
    params[:data][:relationships] = {
      book: {
        data: {
          type: "books",
          id: book_id
        }
      }
    }
  end

  return params
end

Special note on the relationship settings - only add relationships to params if there is a relationship, otherwise, setting it to nil is telling JSON API to remove that relationship, instead of ignoring it.

Then I can call my test like so:

test "chapter create - should create new chapter assigned to an existing book" do
  assert_difference "Chapter.count", +1 do
  post chapters_path, params: format_jsonapi(@new_chapter, @book.id), headers: user_authenticated_header(@jim)
  assert_response :created

  json = JSON.parse(response.body)

  attributes = json['data']['attributes']

  assert_equal "Cooked Wolf Dinner", attributes['title']
  assert_equal 4, attributes['order']
  assert_equal false, attributes['published']
  assert_equal @book.id, json['data']['relationships']['book']['data']['id'].to_i
end