Parameter with Custom Type Error Message

Support dry-validation
1

I would like to test that a required parameter with a custom type (File) is present and if not, I would like have a custom error message. I saw this was asked in Dec, 19. I’m wondering if anything has changed.
ref: Custom type error message

2

Took me some time to figure it out. I could not see an obvious way to do it inline in the code, but by using an error messages YAML file, I was able to achieve the end I wanted.

With a rule set like:

class UploadContract < Dry::Validation::Contract
  config.messages.top_namespace = 'upload_file'
  config.messages.default_locale = 'en'
  config.messages.load_paths "path/to/errors.yml"

  schema do
    required(:filename).filled(:string)
    required(:import_file).filled(type?: ActionDispatch::Http::UploadedFile)
  end

  rule(:import_file) do
    unless ["text/csv", "text/plain", "application/csv"].include?(values[:import_file].content_type)
      key.failure(:invalid_content_type)
    end
  end
end

And a config like:

en:
  upload_file:
    errors:

      rules:
        filename:
          filled?: "Must have a filename."

        import_file:
          filled?: "Upload File Required"
          invalid_content_type: "The import file must have a content type of CSV."

Hopefully that helps someone else.

If folks know a better way, please let me know.