Compatibility with grape 2.2.0

[padde]

Running on the latest 2.2.0 release of grape will produce these exceptions:

NameError:
  uninitialized constant Grape::ContentTypes::CONTENT_TYPES
# ./lib/grape-swagger/endpoint.rb:15:in `content_types_for'

NoMethodError:
  undefined method `formatters' for module Grape::Formatter
# ./lib/grape-swagger/endpoint.rb:14:in `content_types_for'

Used here:

• https://github.com/ruby-grape/grape-swagger/blob/v2.1.0/lib/grape-swagger/doc_methods/produces_consumes.rb#L10
• https://github.com/ruby-grape/grape-swagger/blob/v2.1.0/lib/grape-swagger/endpoint.rb#L15

Grape has removed/renamed these constants/methods via ruby-grape/grape@fb67ea9#diff-e28e889e3579545f8e2fedc3ab52f78530206ed808afdc9a23703f8b089f80e3

[padde]

I'd love to work on a fix, however I am not sure what the correct solution would be here. I'd be grateful for any guidance.

Here is a first attempt: #939

[olivier-thatch]

We just ran into this after Dependabot upgraded the grape gem.

Unless a fix is going to be released soon, I would recommend releasing a new patch version that updates the gemspec to change the < 3.0 grape constraint to < 2.2.

[padde]

So I had started working on a fix for this but apparently it's not as easy to solve as I thought. What I've found so far:

grape-swagger references some internal constants and methods of grape regarding content types and formatters, which were removed/renamed with its 2.2.0 release.

@dblock suggested just copying over those constants from grape which I have done in my PR but this should really only be seen as a temporary fix.

I am saying this because from what I understand, referencing these constants was never really giving us the expected result in the first place. Grape allows specifying custom content types and formatters in the DSL, which seem to have been disregarded by grape-swagger the whole time. Personally, I would not attempt to fix this in the same PR as we might have to spend a considerable amount of work to come up with a solution that actually works for older and newer grape versions as well as new test cases. I think we should treat this issue as a separate bug.

[padde]

I see this issue has already been reported a few years ago, for reference: #700

[dblock]

@padde You're absolutely right. Fixing #700 is beyond the basic compat scope, so let's keep it that way. Thanks for picking the simple fix up.

[dblock]

I released 2.1.1.