Add optional functionality to pre process and extract parameters.

[mtparet]

Description

The goal is to extract and pre process parameters of the request.

For example Rails, by default, transforms empty array to nil value, for some people it could be better to transform it again to an empty array.

Or if we want to support a custom parameter type, like enumeration (comma separated values), this could be used to transform automatically the string parameter, representing an enumeration, to an array.

Usage

To use it, set processing_value configuration variable to true.

Apipie.configure do |config|
  config.process_values = true
end

In your controller action, use values variable instead of params.

To implement a custom pre processing, the idea is to write a process_value function in the validator:
function in your validator:

   def process_value(value)
    value ? value.split(',') : []
   end

as

In the same time, I added an option in parameter description: as.
The idea is to add the possibility to have a mapping/separation between names we expose to the external world and the names we use internally.

example:

param :client, Hash, as: :user do
  param :default_language, String, as: :locale
  param :name, String
end

not processed params:

params : { 'client': {'default_language': 'en', 'name': 'toto'} }

processed params (available through api_params:

api_params: {user:{locale: 'en', name: 'toto'}}

What do you think about this functionality in Apipie ?

[iNecas]

Interesting idea! It could also probably used as way to prevent multi_assignment issues, accepting only the documented params. I'm not sure about @values being the best name for it. Not saying I have better name :) Maybe something like @api_params?

[iNecas]

Good point, I'm not sure we didn't go for it from the start. Maybe there was some reason, if there is, I bet it will be rediscovered while trying converting that into filter.

[mtparet]

Thanks! Indeed we are using it also for multi_assignment issues. values is a history legacy from a previous try from scratch. I agree api_params could be a better name.

Almost all the modification I proposed in these PRs are (or will be) used in production.

[mtparet]

I added a description about internal_name and I renamed values to api_params

[mtparet]

I changed internal_name for as

[iNecas]

the instance param for @api_params is probably unnecessary, what about:

  if @hash_params && value
    return @hash_params.each_with_object({}) do |(key, param), api_params|
      if value.has_key?(key)
        api_params[param.as] = param.process_value(value[key])
      end
    end
  end

[mtparet]

I never used each_with_object before. It seems better with it, thanks !

[iNecas]

Very nice PR, merging now

[iNecas]

sry, one more thing: could you rebase against the latest master, probably some conflict in README

[mtparet]

Just rebased against master

[iNecas]

Thank you!

[iNecas]

Released in 0.1.0. Thank you for your help!