ajax – Not getting values from Select Fields with jQuery – Education Career Blog

I’m trying to implement some basic ajax functionality in website I’m creating. I’m using the Flask microframework and jQuery to do this. I have a lot of experience with python, what Flask is written in, but very little with javascript. This would be why I decided to use jQuery. 😉 There is a nice example included with the Flask documentation which I didn’t have any trouble getting working, but when I applied the method in the example to my code I started running into problems getting jQuery to correctly populate the query string. Essentially, it parses some of my form elements, but not all.

My HTML form looks like this:

<form action method="GET" class="span-11 inline"> 
    <fieldset> 

    <div class='span-5'> 
    <label for="msat_size">Msat Size:</label> 
    </div> 

    <div class='span-5 last'> 
    <select id="msat_size" name="msat_size"><option value="mono">Mono</option><option value="di">Di</option><option value="tri">Tri</option></select> 
    </div> 

    <div class='span-5'> 
    <label for="msat_length">Msat Length:</label> 
    </div> 
    <div class='span-5 last'> 
    <input class="text" id="msat_length" maxlength="3" name="msat_length" size="3" style="width:48px" type="text" value="0" /> 
    </div> 

    <div class='span-5'> 
    <label for="msat_perfect">Perfect Msats:</label> 
    </div> 
    <div class='span-5 last'> 
    <input id="msat_perfect" name="msat_perfect" type="checkbox" value="y" /> 
    </div> 

    <div class='span-5'> 
    <label for="combine_loci">Combine Microsatellites:</label> 
    </div> 
    <div class='span-5 last'> 
    <input id="combine_loci" name="combine_loci" type="checkbox" value="y" /> 
    </div> 

    <div class='span-5'> 
    <label for="design_primers">Design Primers:</label> 
    </div> 
    <div class='span-5 last'> 
    <input id="design_primers" name="design_primers" type="checkbox" value="y" /> 
    </div> 

    <div class='span-5'> 
    <label for="tag_primers">Tag Primers:</label> 
    </div> 
    <div class='span-5 last'> 
    <select id="tag_primers" name="tag_primers"><option selected="selected" value="None">No Tag</option><option value="cag">CAG Tag</option><option value="m13">M13R Tag</option></select> 
    </div> 

    <div class='span-5 prepend-5 last'> 
            <button id="submit_msats" name="submit_msats" type="submit" value="submit_msats" class="button positive"> 
                <img src="/static/css/plugins/buttons/icons/tick.png" alt=""/> Submit
            </button> 
    </div> 
    </fieldset> 
</form>    

My javascript looks like this:

<script type=text/javascript>
  $(function() {
    $('.button').bind('click', function() {
      $.getJSON('/query_result', {
        msat_size: $('inputid="msat_size"').val(),
        msat_length: $('inputname="msat_length"').val(),
        msat_perfect: $('inputname="msat_perfect"').val(),
        combine_loci: $('inputname="combine_loci"').val(),
        design_primers: $('inputname="design_primers"').val(),
        tag_primers: $('inputname="tag_primers"').val(),
        }, function(data) {
        $("#stat1").text(data.msat_size),
        $("#stat2").text(data.msat_length);
      });
      return false;
    });
  });
</script>

But after I submit my query string looks like this:

/query_result?msat_length=0&msat_perfect=y&combine_loci=y&design_primers=y

I can get the ‘msat_length’ value to change properly, none of the others. If I change the .val() to .text() in ‘msat_size’ line in the javascript, the name will appear in the query string, but without a value

/query_result?msat_size=&msat_length=0&msat_perfect=y&combine_loci=y&design_primers=y

Any thoughts on how to fix this would be greatly appreciated. Thanks!

Instead of doing all that complicated work, you should try taking advantage of jQuery’s .serialize() method. Try it like this:

$(function() {
    $('.button').bind('click', function() {
        $.getJSON('/query_result?' + $(this).closest('form').serialize(), function(data) {
            $("#stat1").text(data.msat_size), $("#stat2").text(data.msat_length);
        });
        return false;
    });
});

Here’s the documentation on the .serialize() method: http://api.jquery.com/serialize/

And a demo showing it in action: http://jsfiddle.net/Ender/q3mdw/

Putting aside issues of your approach to serialization, the immediate cause of the problem is that you’re misidentifying some of your form elements:

msat_size: $('select#msat_size').val(), // select, not input
msat_length: $('input#msat_length').val(), // bracket notation unnecessary
msat_perfect: $('input#msat_perfect:checked').val(), // using ID is better
combine_loci: $('input#combine_loci:checked').val(), // use :checked
design_primers: $('input#design_primers:checked').val(),
tag_primers: $('select#tag_primers').val() // select, not input

This assumes you only want the checkbox values if they’re checked. You can of course add conditional logic to omit the checkboxes if they’re unchecked, or provide a default value.

try this

  $(function() {

    $('#submit_msats').bind('click', function(ev) {

      ev.stopPropagation();

      var context = $('form'),
          sendData =  {
            msat_size: $('#msat_size', context).val(),
            msat_length: $('#msat_length', context).val(),
            msat_perfect: $('#msat_perfect', context).val(),
            combine_loci: $('#combine_loci', context).val(),
            design_primers: $('#design_primers', context).val(),
            tag_primers: $('#tag_primers', context).val()
          };

      alert(sendData.msat_length);

      $.getJSON('/query_result', sendData, function(data) {

        $("#stat1").text(data.msat_size),
        $("#stat2").text(data.msat_length);

      });

      return false;
    });
  });