Post ajax requests parameters are sometimes sent in the wrong format to rails

My problem is so weird:

1. I have this form:

   <form id="my-form" method="post" action="/password_reset/update/<%= @user.perishable_token %>" charset="utf-8" autocomplete="off">
     <input type="password" name="user[password]" class="required" minlength="6" />
     <input type="password" name="user[password_confirmation]" class="required" equalto="#password-field" minlength="6" />
     <input type="hidden" name="page" value="set" />
     <input type="submit" value="Submit"/>
   </form>
   

2. The client send an ajax request to my rails server (using jquery 1.6.1, jQuery Validation Plugin 1.8.1, jQuery Form Plugin 2.67)

   $("#my-form").validate({
     submitHandler: function(form) {
       $(form).ajaxSubmit();
     }
   });
   

3. The server side receives the request and here is the probleme. Sometimes:

   • Instead of get parameters with the expected format as below

     Parameters: {"user"=>{"password"=>"[FILTERED]", "password_confirmation"=>"[FILTERED]"}, "page"=>"set", "id"=>"开发者_如何学运维bFC7bkz6tzOF4i2KXZ"}

   • ... I get:

     Parameters: {"_json"=>"user%5Bpassword%5D=password&user%5Bpassword_confirmation%5D=password&page=set", "id"=>"perishable_token"}

I tested the form in lots of cases (with different browsers/OS) and it's impossible to me to reproduce this problem. I can just see it in my production rails log.

So my questions are:

• Why this problem can happen ?
• How can I reproduce this bug ?

Thank you very much for your help.

Try set datatype, that you want:

$(form).ajaxSubmit({dataType=>"desirable format"});  

format may be "xml", "script" or "json"