Missing param raises an InvalidFormatter error?

[dblock]

A POST request to an API with requires :token yields this without a token:

  1) test requires a token (Aprb.Api.SlackTest)
     test/api/slack_test.exs:13
     ** (Maru.Exceptions.InvalidFormatter) Parsing Param Error: token
     stacktrace:

Seems like there're two problems.

1. This is not a formatter error, it's some kind of missing or invalid parameter error.
2. Shouldn't this be handled and turned into a 400 Bad Request error and not raise?

[falood]

1. I defined all parameter errors as InvalidFormatter. I'll check how grape do this later.
2. All exceptions will be caught by rescue_from. I think we should mostly catch similar exceptions by rescue_from and return custom error to client. As a result I raise exceptions instead of rendering an error page.
   Plug 1.2.0 released recently and I have a plan to show plug error page by default for :dev environment.

[dblock]

Grape has error formatters and default handling. It feels like the default for JSON should return a JSON error. This would be much more convenient and logical IMO, there's no user out there who wants a 500 with an HTML page that gives you a call stack and an exception when you supply an invalid parameter for example.

[dblock]

InvalidFormatter is just a poorly worded name I think. It says "the formatter is invalid", probably meant to say "the format is invalid"?

[falood]

So the only thing I should do is change name and printed message of the exception module?
For example:

 ** (Maru.Exceptions.InvalidFormat) :token is required.

or

 ** (Maru.Exceptions.InvalidFormat) :age is illegal.

[falood]

2. Shouldn't this be handled and turned into a 400 Bad Request error and not raise?

I'll think more about how to handle it by default.

[dblock]

Yes on the exception name it would be a start.

I would namespace the parameter exceptions, maybe Maru.Exceptions.Validations.InvalidFormat and such? And they all would inherit form Maru.Exceptions.Validations.ValidationError so that they can be caught together?

[falood]

There's no inherit in elixir world, I must remake namespace in elixir way.