Add nested validator to validate nested children

[mtparet]

The goal of this validator is to validate each element inside of the array.

It enable to validate this kind of parameters:

{ 
  user_id: 5,
  comments: [
   {
     name: 'name of comment1'
     comment: 'blabla1'
   },
  {
     name: 'name of comment2'
     comment: 'blabla2'
  }
  ]
}

The definition of the parameters will be:

param :user_id, Integer
param :comments, Array do
    param :name, String
    param :comment, String
end

I think this validator could be useful for many people and so should be included by default in the gem.

Any remarks ?

[iNecas]

You're on fire! Seems like it might solve the #151 issue, right?

What it it worked this way (as suggested in #151):

param :user_id, Integer
param :comments, Array do
  param :name, String
  param :comment, String
end

Will try to find some time over the weekend to look though the rest of the PRs, with plan of having new version released next week with this changes (and perhaps some others that I manage to review)

[mtparet]

In fact, I'm not sure Array is a better name.
Array should succeed to validate this kind of structure without nested hash:

ids: [4, 10, 6, 7]  
comments: ['string1', 'string2']

so the parameters definition will be like:

param :comments, Array do
  param nil, String # no name for the parameter
end

param :ids, Array do
  param nil, Integer # no name for the parameter
end

which is different from what I implemented which can validate this kind of structure:

  comments: [
   {
     name: 'name of comment1'
     comment: 'blabla1'
   },
  {
     name: 'name of comment2'
     comment: 'blabla2'
  }
  ]

But perhaps we could find a solution where Array could work for both structures (with and without nested hash).

[iNecas]

For the example above, it might be something like:

param :ids, array_of(String)

What do you thing about this?

[mtparet]

or why not just using brackets ?

param :ids, [String]

[iNecas]

That looks good!

[mtparet]

I committed the changes to use Array instead of :nested. I'm not sure I will have the time to implement the simple Array validator [Type] this week. (But this PR could be merged without it)

[iNecas]

Nitpicker: could the block.arity be less than 0?

[mtparet]

I don't know I just copied the one used for Hash without thinking about it :(
https://github.com/Pajk/apipie-rails/blob/master/lib/apipie/validator.rb#L204

[mtparet]

I'm checking this.

[iNecas]

Ah, arity can be negative, when optional args are given http://www.ruby-doc.org/core-2.1.0/Proc.html#method-i-arity. Anyway, I'm quite sure we want to have enough 0 there.

[mtparet]

Thanks, you are right, == 0 should be better.

[iNecas]

Nice, I have one nitpicker comment left, but all looks great otherwise

[iNecas]

Fixes #151

[iNecas]

Thanks a lot for this patch! Great job

[iNecas]

Released in 0.1.0. Thank you for your help!