Forms

Django · Reference cheat sheet

📋 Overview

Django forms validate and clean user input, then render HTML widgets. Use Form for unbound data and ModelForm to map model fields. Always validate with is_valid() and read cleaned_data—never raw request.POST for business logic.

🔧 Core concepts

Piece	Role
`forms.Form`	Standalone fields + validation
`forms.ModelForm`	Bound to a model
`clean_<field>` / `clean`	Field-level / cross-field validation
Widgets	Control HTML input types
CSRF	`\{% csrf_token %\}` on POST forms
Formsets	Edit collections of forms

Bound form: data from request; unbound: empty for GET display.

💡 Examples

ModelForm:

from django import forms
from .models import Article


class ArticleForm(forms.ModelForm):
    class Meta:
        model = Article
        fields = ("title", "slug", "body")
        widgets = {
            "body": forms.Textarea(attrs={"rows": 10}),
        }

    def clean_title(self):
        title = self.cleaned_data["title"].strip()
        if len(title) < 3:
            raise forms.ValidationError("Title too short.")
        return title

View usage:

from django.shortcuts import redirect, render
from .forms import ArticleForm


def article_create(request):
    if request.method == "POST":
        form = ArticleForm(request.POST)
        if form.is_valid():
            article = form.save(commit=False)
            article.author = request.user
            article.save()
            return redirect(article)
    else:
        form = ArticleForm()
    return render(request, "blog/article_form.html", {"form": form})

Template:

<form method="post" novalidate>
  {% csrf_token %}
  {{ form.non_field_errors }}
  {{ form.as_p }}
  <button type="submit">Save</button>
</form>

⚠️ Pitfalls

Skipping CSRF on POSTs yields 403.
form.save() on invalid forms is wrong—check is_valid() first.
fields = "__all__" may expose fields you did not intend.
File uploads need request.FILES and enctype="multipart/form-data".

Forms

Forms

📋 Overview

🔧 Core concepts

💡 Examples

⚠️ Pitfalls

🔗 Related

On this page