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
Jul 21, 2022Technology
Codemirror: unit-testing codemirror react components

One of our recent projects includes the functionality of an inline code editor. This code editor needed to be highly extensible and have custom features. To address this, we chose Codemirror v6 due to its peculiar architecture - it is highly customizable, and all the additional features are provided into codemirror engine as Extension objects.

Jun 8, 2022Technology
How to Use MongoDB in Python: Gearheart`s Experience

In this article, we have prepared a quick tutorial on how to use MongoDB in Python and listed top ORM.

May 12, 2022Technology
Increasing performance by using proper query structure

Earlier in our previous article "Improve efficiency of your SELECT queries" we discussed ways to profile and optimize the performance of SELECT queries. However, to write complex yet efficient SQL queries, there is a thing to remember about.

Apr 27, 2022TechnologyBusiness
How to Choose the Best Javascript Framework: Comparison of the Top Javascript Frameworks

In our article, you will find the best JavaScript framework comparison so that you know for sure how to choose the right one for your project.

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.

Feb 18, 2010Technology
Business logic in models

In my recent project there was a lot of data business logic, so I had to organize this code somehow. In this article I'll describe a few hints on how to it.