Maru ignores input parameter if its value is null

[take-five]

Hello!

I wanted to give Elixir a try and tried to implement very simple JSON API using Maru. Maru is looking good for me at the moment, but I've found strange behavior recently.

Here is Maru router which describes what I've found:

defmodule API do
  before do
    plug Plug.Parsers,
      pass: ["*/*"],
      json_decoder: Poison,
      parsers: [:urlencoded, :json, :multipart]
  end

  params do
    optional :phone, type: String
  end
  post do
    conn |> json(params)
  end
end

I expect that this endpoint will return a JSON containing exact value of given phone param. It works in most cases:

$ curl -H "Content-Type: application/json" -X POST -d '{"phone":"123"}' http://localhost:4000/
{"phone":"123"}

But if I pass "null" value, maru will discard this parameter completely:

$ curl -H "Content-Type: application/json" -X POST -d '{"phone":null}' http://localhost:4000/
{}

This behaviour restricts JSON API very much, so as an API designer I can't provide ability to use null values for certain keys (which is necessary in my case).

Is this intentional or is it a bug? Thanks :)

[falood]

Hi @take-five , This is intentional. It's suitable in my case and I followed this guide Null_Property_Values. Could you please show me your case used it?

[take-five]

I'm designing a simple REST API which supports CRUD operations. Let's say, I want to update user information via REST API. "phone" column can have null values, it's a legacy DB and I can't change it. So how do I set "phone" to null via REST API? I can pass empty string, but that's very confusing for API user.

[take-five]

Also, I guess Google guide refers mostly to JSON response rather than request

[falood]

how about decide whether keep it by an option like this: when I pass {"phone": null} to endpoint, optional :phone, keep_blank: true will get %{phone: nil} and optional :phone will get %{} ?

[take-five]

Sounds like a good plan. Will optional :phone, keep_blank: true implicitly set parameter to nil if it wasn't passed? I believe it shouldn't.

[falood]

It shouldn't.