Render JSON: Remove null fields

Question

I need to avoid having null fields when rendering a JSON from a Ruby-on-Rails API:

def index
  @items = Item.all
  render json: @items,
end

If my Item objects contain nil fields, they are serialized as null in the JSON. I'd just like to eliminate the null fields from my JSON.

Is there any option to render for this purpose?

EDIT: Sample output

[{
    "id": 2,
    "code": "code",
    "list_id": 1,
    "created_by": "me",
    "comment": null
}]

EDIT: Duplicate of this post ?

The post mentionned has an answer that is not really generic. I'd like to find a solution that would be appliable anywhere with a simple parameter on the render (let's say some skip_nil_values parameter, for example). The answer to this post nor doesn't mention how to do it, neither how to handle systematically nested objects in the returned JSON.

I'd like to avoid having bloated as_json everywhere in my API, each time redefined manually for each new endpoint.

As a last argument, the mentionned post is refering to Rails 3.2 . I'm in Rails 5.2 . There may be some improvements between these two versions.

Answer 1

There is a compact method in Rails that returns a hash with non nil values. You may use: @items.map(&:compact)

Answer 2

Create the following private method in your application controller (name it whatever you want).

def format_collection obj_col
  obj_col.as_json.each do |obj|
    obj.reject! { |key, value| value.nil? }
  end
end

Replace your render line with the following.

render json: format_collection @items