Question

When I post data to the server as JSON via AJAX, values from form elements come is as strings (unicode). Here’s a simple example:

<select id="test">
  <option value=1>One</option>
  <option value=2>Two</option>
  <option value=3>Three</option>
</select>

Sending data to the server like this:

$('test').change(function(){
  var id = $(this).val();
  $.ajax(
  {
    type: 'POST',
    contentType: 'application/json; charset=utf-8',
    url: someUrl,
    data: JSON.stringify(id:id),
    dataType: 'json',
    success: doSomething
  });

Then on the server (Pyramid 1.3.3):

log.debug(type(request.json_body['id'])) gives <type 'unicode'>

This makes code like if request.json_body['id'] == 2 False since the value is actually u’2′.

I’ve been doing id = int(request.json_body['id']) for all the params that should be ints, but is there a better way? I feel like I’m missing something obvious.

Answer 1

No, this is correct. Form element values in a web page are always strings, regardless of what you expect the end-users to enter.

You can use collander to automate the conversion on the server side though. You specify a schema, pass in the decoded JSON data structure and get a nice Python structure back, fully validated.

The simplest possible example for deserializing integers:

>>> import colander
>>> id = colander.SchemaNode(colander.Integer())
>>> id.deserialize('1')
1

but colander can handle mappings, sequences, booleans, datetime objects, and much more besides.