typecast_params wrong behaviour with array!(:any, 'arr')

[PetrKaleta]

Lets say we have a very simple roda 3.37.0 app

class App < Roda
  plugin :typecast_params

  route do |r|
    r.post 'test' do
      arr = typecast_params.array!(:any, 'arr')
    end
  end
end

So arr must be present in params and must be an array of any objects. So this request should pass:

curl --location --request POST 'http://0.0.0.0:9292/test' \
--header 'Content-Type: application/json' \
--data-raw '{
    "arr": [[1], [1, 2], null]
}'

But I am receiving Roda::RodaPlugins::TypecastParams::Error: invalid value in array parameter foo Yes, it's because I am sending a null value as one object in arr. Which should not be a problem, because I am using any converter.

If I use typecast_params.array(:any, 'arr') everything works good, but in that case arr may not be present in params at all...

[jeremyevans]

array! doesn't look at the type convertor used (and shouldn't because you can override the default type convertors). It is documented to raise an TypecastParams::Error if the returned value is nil or any value in the returned array is nil, so it is operating as expected, and this isn't considered a bug.

In your case, you should probably use array and manually check the resulting value is not nil.