Rails not decoding array of hashes from jQuery correctly

Question

In my view I save an array of hashes in a hidden field

    <div>
       <%= hidden_field_tag :data_filtered, :value => @data_filtered %>
    </div>

My javascript is

$(document).ready(function(){
    freezeTopRow($('#dataTable'));
    $("#export").click(function(){
        var data1 = $("#data_filtered").val()
        $.ajax({
            type: "POST",
            url: "export",
            dataType: 'json',
            data: {data_filtered: data1}
        });
    });
});

My controller is

  def export
    CSV.open("data.csv", "wb") do |csv|
       csv << params[:data_filtered].first.keys
       @data_filtered.each do |hash|
       csv << hash.values
      end
    end
  end

When I view params[:data_filtered] after it has been returned to the controller i see a string:

 "{:value=>[{"a"=>nil, "b"=>nil, "c"=>0}]}"

But I want it to be in its original form of (array of hashes, in this case just 1 hash) half the problem is the :value. I don't want that to be stored and I don't know how to parse that to get just the array. Basically i want

[{"a"=>nil, "b"=>nil, "c"=>0]

What is @data_filtered in your view? Is it a Hash perhaps? — mu is too short
– mu is too short, Commented Jul 1, 2013 at 18:33
Have you considered serializing it manually to a known format so that you can easily unpack it? You're getting the result of calling to_s and that's not meant to be easily parsed. If you use JSON then parsing becomes easier. — mu is too short
– mu is too short, Commented Jul 1, 2013 at 18:56

Muntasim · Accepted Answer · 2013-07-01 17:47:45Z

1

Try to send json data instead of string(that contains hash). If you send string via ajax then in controller you have to eval the params which has SEVERE SECURITY issue.

using eval: (PLEASE DONT USE IT)

eval('{:value=>[{"a"=>nil, "b"=>nil, "c"=>0}]}') will produce the original hash: {:value=>[{"a"=>nil, "b"=>nil, "c"=>0}]}

answered Jul 1, 2013 at 17:47

Muntasim

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6 Comments

user1571609 Over a year ago

how do I send json data instead of the string?

Muntasim Over a year ago

stackoverflow.com/questions/6762735/…

user1571609 Over a year ago

how is that different then what i am doing?

Muntasim Over a year ago

you can find the difference if you inspect the parameter. In current implementation params[:data_filtered] is just a string, but if you send data like: data: {data_filtered: {value: [...]}} then you can get the actual parameters using params[:data_filtered][:value] in your controller

user1571609 Over a year ago

the problem is still the same. now params[:data_filtered][:value] = {:value=>[{"a"=>nil, "b"=>nil, "c"=>0}]} but I want just [{"a"=>nil, "b"=>nil, "c"=>0}]

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