Nested Javascript arrays don't decode well

[mrocklin]

Nested JavaScript arrays in AJAX call data to a ring application fail to parse. I think I can reproduce the error as far down as form-decode.

Disclaimer: I'm new to Ring and web programming in general. Please correct me if this ticket should be filed elsewhere.

AJAX call

$( document ).ready( function() {
    $.ajax({
        url: "/query/",
        data: {want: "C", constraints: [["A", "B"]]},
        success: function(data, aStatus, dummy){
            alert(data);
        }
    });
});

Result on Server

{:scheme :http, :request-method :get, 
 :query-string want=C&constraints%5B0%5D%5B%5D=A&constraints%5B0%5D%5B%5D=B, 
 :route-params {}, :content-type nil, :params {}, 
 :body #<HttpInput org.eclipse.jetty.server.HttpInput@1bd06bf>
 ....}

(clojure.pprint/pprint (-> result :query-string form-decode))

{"constraints[0][]" ["A" "B"], "want" "C"}

Desired Result

{"constraints" [["A" "B"]], "want" "C"}

[weavejester]

You don't seem to be applying the wrap-nested-params middleware. Nested parameters are not something inherent to HTTP; they're simply a convention adopted by certain frameworks. In Ring you have the option of using this syntax via the wrap-nested-params middleware.

However, the desired result you want won't work with the input you provide, whether in Ring:

user=> (nested-params-request {:params {"contraints[0][]" ["A" "B"], "want" "C"}})
{:params {"want" "C", "contraints" {"0" ["A" "B"]}}}

Or in Rails:

irb> Rack::Utils.parse_nested_query("constraints[0][]=A&constraints[0][]=B&want=C")
=> {"constraints"=>{"0"=>["A", "B"]}, "want"=>"C"}

[eigenhombre]

@weavejester Is the conversion of {constraints: [["A", "B"]]} into {"constraints[0][]" ["A" "B"]} done on the jQuery side, or the Ring side? Because nested arrays serialize just fine into JSON in general:

>  python
Python 2.6.8 (unknown, Nov 17 2012, 21:23:35) 
>>> import json
>>> json.dumps({"want": "C", "constraints": [["A","B"]]})
'{"want": "C", "constraints": [["A", "B"]]}'

@mrocklin You don't state in the ticket if this gives the same result with a POST as it does with GET. Does it? Because GETs have to stuff their parameters into the HTTP URL arguments, I can understand why this would go sideways -- but maybe POSTs are more robust (since you can just pass data, unmunged...?).

I guess I'm confused exactly where this simple thing is breaking down. And, what people usually do about it. Thanks!

[mrocklin]

Post does better because it does actually decode the query-string and push the result into the :params key (EDIT: this is probably because I started wrapping my routes with compojure.handler/api). However it also fails to a nested array. I suspect that this still depends on form-decode.

$.post("/query/", {want: "C", constraints: [["A", "B"]]},
    function(data, aStatus, dummy){
        alert(data);
    });

{:scheme :http,
 :query-params {},
 :form-params {"constraints[0][]" ["A" "B"], "want" "C"},
 :request-method :post,
 :query-string nil,
 :params {:want "C", :constraints {"0" ["A" "B"]}},
 :body #<HttpInput org.eclipse.jetty.server.HttpInput@16535bf>}

From what @weavejester writes it seems that my issue is really what I should expect from any system. It seems like the best path may be to kludge together a local array-from-map function.

[weavejester]

@weavejester Is the conversion of {constraints: [["A", "B"]]} into {"constraints[0][]" ["A" "B"]} done on the jQuery side, or the Ring side?

On the jQuery side, since that's where the request is coming from.

From what @weavejester writes it seems that my issue is really what I should expect from any system. It seems like the best path may be to kludge together a local array-from-map function.

Or just use JSON, instead of trying to encode a data structure in form parameters, which aren't really designed for that.