How do I process a complex graphical UI element in a django form?

Question

I have a few complex GUI elements (like a custom calendar with many days that can be highlighted) that appear along with standard django form input fields. I want to process the data I/O from these complex forms along with the Django forms.

Previously I would use AJAX requests to process these custom GUI elements on my HTML form after the Django form was saved or rendered, but this leads to a host of problem and customized AJAX coding. What is a good way to handle complex interactions widgets in a Django form?

Answer 1

Not sure if I understand completely, but you could have the value of your UI saved into a hidden element on the form via javascript. This can either be done as they select the values in the UI or when they submit the form. Pseudo-code assuming JQuery using submit() to save before the submit data is sent:

$('#myForm').submit(function(){
  // get the value of your UI
  var calendarValue = calendarWidget.getValue()

  // #calendarData is the hidden field
  $('#calendarData').val(calendarValue)
})

This obviously requires JS, but so does using your UI element.

Answer 2

Your question is very vague so I suggest you read the Django documentation on writing a custom field and hopefully that will help you get started. You might also want to investigate writing a custom widget. Unfortunately the documentation is bit lacking on that, but a Google search brings up several useful blog posts, including this one.

Answer 3

You have three options depending on how you output your Django Form subclass to the HTML page.

The first doesn't involve Form at all. Any html form inputs will end up in request.POST, so you can access them there. True, they won't be bound to your Form subclass, so you would have to manually inject the value either using a custom form constructor, or by setting some property on your Form object after instantiating it with request.POST. This is probably the least desirable option, but I mention it in case your use-case really doesn't support anything else.

The second is an option if you manually output the form fields in your HTML (ie: using {{ myform.field }} rather than just {{ myform }}. In this case, make a hidden variable to contain the value of your calendar GUI tool (chances are, your GUI tools already offer/require one). Add this hidden field, with the right name and ID, to the Form subclass itself, making sure it has a hidden django form widget. If necessary, use javascript as Rob suggests to populate the hidden field. When the form is posted, it will get bound to your form subclass as normal because, this time, you have a field on your Form subclass with that name. The machinery for clean() will work as normal.

The third, and best option, is to write a custom django field; Andrew's post has the link. Django fields have the ability to specify js and css requirements, so you can automatically encapsulate these dependencies for any page that uses your calendar widget.