Rails - Parameter with multiple values in the URL when consuming an API via Active Resource

问题

I am consuming an API that expects me to do requests in the following format:

?filter=value1&filter=value2

However, I am using Active Resource and when I specify the :params hash, I can't make the same parameter to appear twice in the URL, which I believe is correct. So I can't do this:

:params => {:consumer_id => self.id, :filter => "value1", :filter => "value2" }, because the second filter index of the hash will be ignored.

I know I can pass an array (which I believe is the correct way of doing it) like this:

:params => {:consumer_id => self.id, :filter => ["value1","value2"] }

Which will produce a URL like:

?filter[]=value1&filter[]=value2

Which to me seems ok, but the API is not accepting it. So my question are:

What is the correct way of passing parameters with multiple values? Is it language specific? Who decides this?

回答1:

to create a valid query string, you can use

params = {a: 1, b: [1,2]}.to_query

http://apidock.com/rails/Hash/to_query
http://apidock.com/rails/Hash/to_param

回答2:

http://guides.rubyonrails.org/action_controller_overview.html#hash-and-array-parameters

Try :filter[] => value, :filter[] => value2

回答3:

You can generate query strings containing repeated parameters by making a hash that allows duplicate keys. Because this relies on using object IDs as the hash key, you need to use strings instead of symbols, at least for the repeated keys.

(reference: Ruby Hash with duplicate keys?)

params = { consumer_id: 1 } # replace with self.id
params.compare_by_identity
params["filter"] = "value1"
params["filter"] = "value2"
params.to_query #=> "consumer_id=1&filter=value1&filter=value2"

来源：https://stackoverflow.com/questions/9713382/rails-parameter-with-multiple-values-in-the-url-when-consuming-an-api-via-acti