Back
Mar 6, 2010

Ajax form validation

There was a task to submit form with ajax, with server side validation of course. Obvious solution is to do validation and return json with erros.

I didn't like idea of writing separate view for validation and then inserting errors in form html on client side. Especially since I already had a generic template for django form with errors display.

Task

User will see process like this:

  • User clicks 'edit' near article block
  • article is replaced with form
  • in case there are validation errors - they are shown above the form fields
  • in case there are no errors - form is replaced by article html

Solution

Server will return piece of html that will replace part of page with article or form (with errors if needed). Actually this sentence is the most important part of this blog post. Implementation is very simple and straightforward.

Well actually the fact that you can return parts of html from server is also not new idea at all. It's just only now I finally understood that using this technique you can create more complicated things than modal window or tabs.

Implementation

views.py

def edit_new(request, new_id):
    new = get_object_or_404(MyModel, pk=new_id)
    if request.method == 'POST':
        form = NewsForm(request.POST, instance=new)
        if form.is_valid():
            new = form.save()
            return render_to_response('include/new.html', dict(new=new))
    else:
        form = NewsForm(instance=new)

    return render_to_response('include/form.html', dict(form=form, new=new))

form.html

This html will replace article block on 'edit' button click. Javascript should be moved to separate file of course.

<script type="text/javascript">
  function submitAndLoad(input) {
    $.ajax({
      url: "{% url edit_new new.id %}",
      data: $(input).parent().serialize(), // форма
      type: "post",
      dataType: "html",
      success: function(data) {
        $(input).parent().parent().html(data); // article block
      }
    });
    return false;
  };
</script>
<form>
  {{ form }}
  <input type="submit" value="Save" onclick="return submitAndLoad(this);"/>
</form>

news_list.html

<script type="text/javascript">
  function editNew(id) {
    $("#new-" + id).load("{% url edit_new new.id %}");
    return false;
  }
</script>

<!-- ... -->

<div id="new-{{ new.id }}">
  {% include "news/new.html" %}
</div>
<a onclick="return editNew({{ new.id }});" href="#">Edit</a>

Code can be cleaned up of course, I just wanted to show the idea.

Update

I'm translating this article almost five years after it was originally written and of course now it seems very childish :) Now we have angular and ajax forms are implemented a little differently. Still this old solution is not all that bad. I'd still replace one thing here - it's better to return json with html from server instead of just html.

Subscribe for the news and updates

More thoughts
Feb 3, 2025Technology
Figma for Developers: What Dev Mode Offers and How to Use It

This article explores Figma’s Dev Mode, a tool that streamlines design-to-code translation by enabling precise inspection, automated code generation, and seamless integration with design systems.

Nov 27, 2024Technology
Stoicism At Work

This article explores how Stoic principles can be applied in the workplace to navigate stress, improve self-control, and focus on what truly matters, with practical examples from the author’s experience in software development.

Mar 18, 2024Technology
From boring to exciting: turn learning to code into an adventure

Tired of boring programming courses where you're forced to read thick textbooks and write code that's never used? Need a platform that makes learning fun and exciting? Then you're in the right place!

Sep 26, 2023TechnologyBusiness
13 Web Development Innovations to Adopt in the Next Year

Web development has undergone significant changes over the past five years due to a combination of technological advancements and changing user needs. Let's look at the drivers of these changes and the key technologies that have played a decisive role.

Oct 22, 2016Technology
Solr Sharding

When dealing with one of our projects (LookSMI media monitoring platform) we have to handle the huge volume of data – and its quantity is constantly growing. At the same time, we must run quick searches with smart rules. In this article I'll explain how we have achieved required performance.

Sep 23, 2010Technology
Dynamic class generation, QuerySetManager and use_for_related_fields

It appears that not everyone knows that in python you can create classes dynamically without metaclasses. I'll show an example of how to do it.So we've learned how to use custom QuerySet to chain requests:Article.objects.old().public()Now we need to make it work for related objects:user.articles.old().public()This is done using use_for_related_fields, but it needs a little trick.