Rails 4: redirect_to :back and change/delete parameters

Question

I think this should be easy but I cannot for the life of me get it to work, or find anything on the web that explains it. After a form submit, I want to redirect back to the referer/referrer and alter or delete one or more of the query parameters.

For example, the form is at

/tasks/6?foo=1&bar=1

And I want to go afterwards to

/tasks/6?foo=0&bar=1

I tried all sorts of combinations based on

redirect_to :back, foo: 0

or

redirect_to :back, params: {foo: 0, bar: 1}

and so on, but nothing at all would redirect me to anything other than the original page. I was hoping to avoid having to mangle with the string myself, but it may come to that.

It would be awesome, too, if there were also a way to just get rid of a parameter altogether, eg redirect to:

/tasks/6?bar=1

Thanks!

Answer 1

:back does not accept other arguments. In order to accomplish what you want to do, you need to get the value of the referrer using

request.referer

or

request.env['HTTP_REFERER']

Parse it with the URI library, extract the query and decompose it with Rack::Utils.parse_query . At this point you have the hash of params.

You can update the hash, and construct the URL for the redirect.