[WIP] Allow Router to handle additional HTTP verbs/methods

[iStefo]

After a brief discussion in this Stackoverflow thread, I continued trying adding custom HTTP methods to the Phoenix Router.

While this option surely comes as a danger (using custom HTTP methods is generally not a favourable desire), it may be necessary to implement some protocols that extend HTTP with own method names, such as WebDAV/CalDAV.

Allowing the programmer to add custom HTTP methods turned out to be more difficult than I originally thought, because the method macros are being generated at phoenix's compile time, and not the application's. That made it impossible to either use

use Phoenix.Router, additional_http_methods: [:move, :copy]

or

defmodule Router do
    @additional_http_methods [:move, :copy]
    use Phoenix.Router
end

However, the current approach uses the projects config files and by adding this command adds any custom methods as desired by the programmer:

# Add additional HTTP methods
config :phoenix, :router,
  additional_http_methods: [:move, :copy]

A short list of tasks that came up to my mind:

• Documentation (Possible in the Router's guide)
• Tests (I don't know how to stub the Application.get_env call to simulate such a config as above)
• The CSRF Plug denies any requests with a custom HTTP Method without a valid CSRF token (this is not a blocker but it would be nice to at least mention this somewhere, right?)

Please tell me what you think about this addition.

[josevalim]

Another approach is to have a match :verb, ... construct that would allow you to provide any HTTP verb without a need to recompile Phoenix. It should be simpler on Phoenix side too.

[iStefo]

@josevalim I see why it would be desirable to add methods without recompiling phoenix, I can't judge the internal complexity, though.

However, creating specific macros that are nicer to use than a generic match construct would be in the spirit of having a nice DSL for the project, wouldn't it?

[josevalim]

@iStefo if we have match(:verb) then you can create your own macros if you want. :)

[chrismccord]

👍 on match primitive. If we are to support this it should be based on a public primitive and not options or module attributes

[iStefo]

Alright, as long as it is possible to create the DSL-like macros, I am in for the match primitive.

Do you see any way I can push this forward and help with the implementation? Or are the internals rather complex for a beginner like me?

[chrismccord]

Do you see any way I can push this forward and help with the implementation? Or are the internals rather complex for a beginner like me?

Unfortunately the router is the most complex bits of phoenix so it might be a lot to take on, but you are welcome to give it a shot. Otherwise, please open a separate issue and I can take care of it :)

[iStefo]

@chrismccord since I have rather little time in the near future to take care of this enhancement, I will gladly open an issue and leave it to people more close to the Router module.