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;
    });
  });

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