Raise proper validation errors on invalid parameter types

[bwalex]

I've run into several issues with validations. For half of the things I don't have a real use case, but it should still work.

1. The following block works both when opts is an array of opts and when it is a single opt (made to work this way in validation for array in params #333). I think there should be a way to specify whether it is actually an array of hashes or a single nested hash.

    params do
      requires :name, type: String, desc: "Foobarness."
      requires :opts do
        requires :opt_a, type: Integer, desc: "Option A"
        optional :opt_b, type: Integer, desc: "Option B"
      end

2. In the same example, if someone passes in something like the following, it blows up with the stack trace below because it doesn't check that "opts" is actually a Hash.

{
  "name" : "foobar",
  "opts" : "moo"
}

2013-12-29 22:01:30 +0000: Rack app error: #<NoMethodError: undefined method `has_key?' for "":String>
/usr/lib/ruby/gems/2.0.0/gems/grape-0.6.1/lib/grape/validations/presence.rb:10:in `validate_param!'
/usr/lib/ruby/gems/2.0.0/gems/grape-0.6.1/lib/grape/validations.rb:25:in `block in validate!'
/usr/lib/ruby/gems/2.0.0/gems/grape-0.6.1/lib/grape/validations.rb:42:in `block (2 levels) in each'
/usr/lib/ruby/gems/2.0.0/gems/grape-0.6.1/lib/grape/validations.rb:41:in `each'
/usr/lib/ruby/gems/2.0.0/gems/grape-0.6.1/lib/grape/validations.rb:41:in `block in each'
/usr/lib/ruby/gems/2.0.0/gems/grape-0.6.1/lib/grape/validations.rb:40:in `each'
/usr/lib/ruby/gems/2.0.0/gems/grape-0.6.1/lib/grape/validations.rb:40:in `each'

3. With the following params block and request, it also blows up, but in a different way, presumably due to the nested parameters:

    params do
      requires :name, type: String, desc: "Foobarness."
      group :tags do
        requires :id, type: Integer, desc: "Tag ID"
        group :foobars do
          optional :fooname, type: String, desc: "Test string"
          optional :fooval, type: String, desc: "Test string"
        end
      end
    end

{
  "name" : "foo",
  "tags" : [
  ]
}

2013-12-29 22:04:01 +0000: Rack app error: #<TypeError: no implicit conversion of Symbol into Integer>
/usr/lib/ruby/gems/2.0.0/gems/grape-0.6.1/lib/grape/validations.rb:136:in `[]'
/usr/lib/ruby/gems/2.0.0/gems/grape-0.6.1/lib/grape/validations.rb:136:in `params'
/usr/lib/ruby/gems/2.0.0/gems/grape-0.6.1/lib/grape/validations.rb:35:in `initialize'
/usr/lib/ruby/gems/2.0.0/gems/grape-0.6.1/lib/grape/validations.rb:22:in `new'
/usr/lib/ruby/gems/2.0.0/gems/grape-0.6.1/lib/grape/validations.rb:22:in `validate!'
/usr/lib/ruby/gems/2.0.0/gems/grape-0.6.1/lib/grape/endpoint.rb:389:in `block in run'
/usr/lib/ruby/gems/2.0.0/gems/grape-0.6.1/lib/grape/endpoint.rb:387:in `each'
/usr/lib/ruby/gems/2.0.0/gems/grape-0.6.1/lib/grape/endpoint.rb:387:in `run'
/usr/lib/ruby/gems/2.0.0/gems/grape-0.6.1/lib/grape/endpoint.rb:154:in `block in call!'

[dblock]

Agreed on (1). Maybe by introducing a type? I should be able to write:

requires :opts, type: Array do
  requires :opt_a, type: Integer, desc: "Option A"
  optional :opt_b, type: Integer, desc: "Option B"
end

For both (2) and (3): these are bugs. The parameter passed is of the wrong type, so you should get an exception that says so.

Leaving this open as-is. It would be a great start if you could make these into Grape tests and opened PRs with the failing ones. Of course, feel free to fix :)

[dblock]

I've renamed this to "Raise proper validation errors on invalid parameter types", I think it captures the problem better.

[bwalex]

Agreed - it was just intended as a placeholder until I get around to either writing some tests and/or fixing it. I'll get back to you as soon as I make some progress on this.

[bwalex]

I've made a fair bit of progress on this, both on tests and fixing/implementing it. However, I've run into a bit of an issue with how query params are handled.

In particular, if something requires an array block, an empty array should be valid. But with how query parameters work, the empty array doesn't really exist, so grape never sees it on the (GET) request.

The way I've implemented it, which is by adding validations for presence and type on the 'requires', etc with block, this fails the 'presence' validation.

In my opinion that's actually fair enough, since it isn't actually present even as an empty array in the request. It's just a quirk to keep in mind with query parameters and groups/requires with blocks, etc. It should work as expected with body parameters, e.g. json, where an empty array is something perfectly valid.

[dblock]

I think the presence issue is much smaller, and you can open it once we have a fix for the bigger problem.

[dblock]

Closing, fixed in 0.7.0.