Allow JSON formatter to return a blank body

[mbleigh]

I think most users expect that body '' or return nil will end up with a blank response, but the current JSON formatter put it as "" instead. This fixes that.

Made it a pull because I want to make sure no one is depending on it returning a blank string. Technically JSON is only valid if it's an Object or Array, but there may be a use case I'm not thinking of.

[dm1try]

Seems like a blank body technically also is not a JSON :) Nevertheless it's more preferable for situation wherebody '' or return nil.

[mbleigh]

Yeah, I considered also making the Content-Type: text/plain when this is the case automatically, but it seems like overkill.

[dblock]

I think this semantically incorrect, whatever we think people expect. Today Grape will serialize and deserialize the values correctly. If you change it above you won't be able to anymore.

2.0.0-p353 :021 > MultiJson.load('null')
 => nil 
2.0.0-p353 :023 > MultiJson.load('""')
 => ""

Wit this change you would be returning an empty result, which isn't valid JSON, and you're not able to load it back.

2.0.0-p353 :024 > MultiJson.load('')
MultiJson::ParseError: JSON::ParserError

Changing content-type on the fly would be an even further stretch I think :)

[dblock]

To clarify what I am saying: today Grape is capable of returning both an empty string and a null. I am not saying the client should rely on that, but it's definitely by design and would be an API change.

[dblock]

This is missing a period at the end :)

[mbleigh]

@dblock do you think it would be better to have an endpoint shortcut for a blank response?

I considered using body false as a way to specify that you don't want to return body content at all. Maybe a special method like blank_response or blank_body?

The major times this comes up for me are with 304 responses and DELETE requests.

[dblock]

Did you check whether raising an error! with a 304 is actually returning a body?

My 0.02c is that you shouldn't be returning an empty body for a DELETE, you should be returning the original object that has been deleted, but that's a preference.

I would definitely vote for something that lets you return an empty body very explicitly. Maybe just return an instance of Grape::Response::EmptyBody or something like that?

[mbleigh]

What do you think of a macro e.g. empty_body! that would set Content-Type to text/plain and body to ''

[dblock]

I think that would work.

[dblock]

Bump.

[rzane]

Any progress on this? It would be really nice to have a Grape equivalent for Rails' head method.

[dblock]

I went with body false, which is just an alias for:

@body = nil
status 204

#850