format: true does not override existing format constraints.

[senny]

Closes #9466.

Passing format: true used to override the constraints: { format: /json/ }
with /.+/. This patch only sets the format if there is no constraint present.

[senny]

/cc @carlosantoniodasilva @rafaelfranca

@pixeltrix can you take a look?

[pixeltrix]

Thanks @senny - I missed this set of options when I refactored the constraints code. This is how I'd do this kind of route:

get '/products.:format', to: 'products#index', format: /json/

i.e. make the required format part of the path.

[rosenfeld]

Thanks, @senny and @pixeltrix. Actually I always found it dumb to have to specify both "format: true" and "format: /json/" in the constraints to force the format. First I did try to do something like:

get '/products.json' => 'products#index'

But that didn't work if I remembered correctly. When I asked in the rails-core list a while ago I was pointed that I should be doing as in the route I pointed out when I reported the issue.

But I certainly prefer your suggested approach, thanks.

[pixeltrix]

@rosenfeld for your example to work you'd have to specify format: false:

get '/products.json' => 'products#index', :format => false

which seems counter-intuitive when you look at it.

[rosenfeld]

@pixeltrix I believe that wouldn't work either for what I want... Look, I don't really care if the URL ends up with ".json" or not. The main reason I started to be concerned about the format is that I realized that when Rails caches some action it doesn't store the response content-type in the cache. So, the first time the action would respond with content-type 'application/json' but next time it would be 'text/html' if I remember correctly. Then I have been told that the cached action will use the content-type based on the format of the request, so I can't use "format: false". And the reason why I want to enforce the format is so that I don't forget about it in my client-side applications when calling some action with jQuery.getJSON (which won't run the callback if the wrong content-type is served). Sorry if this is confusing but I couldn't find any way to simplify that... That's why I ended up grouping all my JSON requests (99.9% of all requests) in a scoped block that would set format to true and the format constraint to /json/ to minimize any maintenance pain from my side...

[rosenfeld]

Ah, and I remembered. Actually my first try was this one if I recall correctly:

get 'products' => 'product#index', format: 'json'