Hidden fields in Django template

Question

I've passed 'Tango with Django' tutorial but still don't get one thing - why we need to use hidden fields in Django template.

For example, if I have a code

class CategoryForm(forms.ModelForm):
    name = forms.CharField(max_length=128, help_text="Please enter the category name.")
    views = forms.IntegerField(widget=forms.HiddenInput(), initial=0)
    likes = forms.IntegerField(widget=forms.HiddenInput(), initial=0)

Ok, here I get, that views and likes won't be filled by user in form, so they are hidden. But, in template, inside the form we have something like:

            {% csrf_token %}
            {% for hidden in form.hidden_fields %}
                {{ hidden }}
            {% endfor %}

            {% for field in form.visible_fields %}
                {{ field.errors }}
                {{ field.help_text }}
                {{ field }}
            {% endfor %}

Why do we need 2-nd and 3-rd rows? And do we need them?

Answer 1

It's difficult to say exactly why, because the reasons could be pretty numerous.

But broadly speaking, it is probably so that those two fields can be modified or accessed client-side by javascript, and then also be submitted back to the server.

If you're not doing any of that, then you probably don't need them :) But you might have to worry about not overwriting those values when you save changes to the other fields.