Custom Validation error messages

[railsmith]

Provides settings for custom validation error messages. Motivated by requests to build this feature on here Grape Custom Validation error message and here #621

If custom error message options are not provided error messages fall backs to defaults specified in grape/locale/en.yml. If you want i18n for your custom error messages passing locale symbol keys will translate the messages.

presence, allow_blank, values, regexp

params do
   requires :name, values: { value: 1..10, message: 'not in range from 1 to 10' },
                            allow_blank: { value: false, message: 'cannot be blank' },
                            regexp: { value: /^[a-z]+$/, message: 'format is invalid' }, 
                            message: 'is required'
end

all_or_none_of

params do
    optional :beer
    optional :wine
    optional :juice
    all_or_none_of :beer, :wine, :juice, message: "all params are required or none is required"
end

mutually_exclusive

params do
    optional :beer
    optional :wine
    optional :juice
    mutually_exclusive :beer, :wine, :juice, message: "are mutually exclusive cannot pass both params"
 end

exactly_one_of

 params do
     optional :beer
     optional :wine
     optional :juice
     exactly_one_of :beer, :wine, :juice, message: {exactly_one: "are missing, exactly one parameter is required", mutual_exclusion: "are mutually exclusive, exactly one parameter is required"}
 end

at_least_one_of

params do
     optional :beer
     optional :wine
     optional :juice
     at_least_one_of :beer, :wine, :juice, message: "are missing, please specify at least one param"
 end

Coerce

 params do
    requires :int, type: {value: Integer, message: "type cast is invalid" }
  end

[dblock]

Thanks! Looking forward to code reviewing this - can you please rebase/squash it first? There're a lot of unrelated changes here to grok.

[railsmith]

I have squashed it. There are still one or two unrelated changes which have penetrated while rebasing. Hope it helps to review the code.

[dblock]

Well those two changes shouldn't be there :) This should fix it:

git checkout master
git pull upstream master
git checkout custom-messages
git rebase master
git push origin custom-messages -f

[dblock]

The change itself looks OK to me. It needs a README update and CHANGELOG. I am glad to see a very full test coverage too, wonder if there's a way to simplify the implementation a bit so that you don't have to copy paste the thing again and again. Like maybe enumerating something in the messages YML?

[railsmith]

Originally I had a similar idea in my mind. We can certainly enumerate messages from a YML file and extract the key based on the current route description. We can first check for the message in the message settings DSL, if it doesn't exist there then we can check in the messages.yml and if it doesn't exist there too we can safely fall back to message keys in en.yml. What do you propose?

# messages.yml

grape:
   errors:
      messages:
         endpoint:
             /custom_messages:
                 verb:
                     get:
                        email:
                            presence: 'is required'
                            blank: 'has no value'
             /:
                 verb:
                     post:
                          number:
                             values: 'not in range 1 to 10'

[dblock]

I don't have any great suggestions wrt your question :)

Please update README and CHANGELOG and this is good to go.

[railsmith]

Thanks! I am done with this.

[dblock]

Merged via e6a6c9c (I re-added a CHANGELOG line "Your contribution here"). Thanks!

[dblock]

This bit me on a real life project, returning empty messages when a Grape::Exceptions::Validation was raised explicitly. I added a note in UPGRADING in 77ec1cd to rename message_key to message. We could have deprecated message_key first with a warning, but I think it's OK to get rid of it here since it's rare to be implementing your own validators and it's easily fixed.

[railsmith]

The spec for Custom Validators with an explicit message_key was indeed failing and I updated the spec by changing message_key to message but forgot to deprecate message_key and update the README for Custom Validators as I thought it was trivial but it looks OK and updated now.