Question

I have a form with an email property.

When using {{ form.email }} in case of some validation error, Django still renders the previous value in the input tag’s value attribute:

<input type="text" id="id_email" maxlength="75" class="required"
       value="[e-mail]" name="email">

I want to render the input tag myself (to add some JavaScript code and an error class in case of an error). For example this is my template instead of {{ form.email }}:

<input type="text" autocomplete="on" id="id_email" name="email"
       class="email {% if form.email.errors %} error {% endif %}">

However, this does not display the erroneous value ([e-mail] in this example) to the user.

How do I get the field’s value in the template?

Answer 1

The solution proposed by Jens is correct.
However, it turns out that if you initialize your ModelForm with an instance (example below) django will not populate the data:

def your_view(request):   
    if request.method == 'POST':
        form = UserDetailsForm(request.POST)
        if form.is_valid():
          # some code here   
        else:
          form = UserDetailsForm(instance=request.user)

So, I made my own ModelForm base class that populates the initial data:

from django import forms 
class BaseModelForm(forms.ModelForm):
    """
    Subclass of `forms.ModelForm` that makes sure the initial values
    are present in the form data, so you don't have to send all old values
    for the form to actually validate.
    """
    def merge_from_initial(self):
        filt = lambda v: v not in self.data.keys()
        for field in filter(filt, getattr(self.Meta, 'fields', ())):
            self.data[field] = self.initial.get(field, None)

Then, the simple view example looks like this:

def your_view(request):   if request.method == 'POST':
    form = UserDetailsForm(request.POST)
    if form.is_valid():
      # some code here   
    else:
      form = UserDetailsForm(instance=request.user)
      form.merge_from_initial()