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To display the form errors, you use form. is_valid() to make sure that it passes validation. Django says the following for custom validations: Note that any errors raised by your Form.
as_p }} – Render Django Forms as paragraph.
You can override forms for django's built-in admin by setting form attribute of ModelAdmin to your own form class. See: https://docs.djangoproject.com/en/dev/ref/contrib/admin/#django.contrib.admin.ModelAdmin.form. https://docs.djangoproject.com/en/dev/ref/contrib/admin/#adding-custom-validation-to-the-admin.
Django ModelForm is a class that is used to directly convert a model into a Django form. If you're building a database-driven app, chances are you'll have forms that map closely to Django models. For example, a User Registration model and form would have the same quality and quantity of model fields and form fields.
If you render the same view when the form is not valid then in template you can access the form errors using form.errors.
{% if form.errors %}
{% for field in form %}
{% for error in field.errors %}
<div class="alert alert-danger">
<strong>{{ error|escape }}</strong>
</div>
{% endfor %}
{% endfor %}
{% for error in form.non_field_errors %}
<div class="alert alert-danger">
<strong>{{ error|escape }}</strong>
</div>
{% endfor %}
{% endif %}
An example:
def myView(request):
form = myForm(request.POST or None, request.FILES or None)
if request.method == 'POST':
if form.is_valid():
return HttpResponseRedirect('/thanks/')
return render(request, 'my_template.html', {'form': form})
views.py
from django.contrib import messages
def view_name(request):
if request.method == 'POST':
form = form_class(request.POST)
if form.is_valid():
return HttpResponseRedirect('/thanks'/)
else:
messages.error(request, "Error")
return render(request, 'page.html', {'form':form_class()})
If you want to show the errors of the form other than that not valid just put {{form.as_p}} like what I did below
page.html
<html>
<head>
<script>
{% if messages %}
{% for message in messages %}
alert('{{message}}')
{% endfor %}
{% endif %}
</script>
</head>
<body>
{{form.as_p}}
</body>
</html>
UPDATE: Added a more detailed description of the formset errors.
Form.errors combines all field and non_field_errors. Therefore you can simplify the html to this:
template
{% load form_tags %}
{% if form.errors %}
<div class="alert alert-danger alert-dismissible col-12 mx-1" role="alert">
<div id="form_errors">
{% for key, value in form.errors.items %}
<span class="fieldWrapper">
{{ key }}:{{ value }}
</span>
{% endfor %}
</div>
<button type="button" class="close" data-dismiss="alert" aria-label="Close">
<span aria-hidden="true">×</span>
</button>
</div>
{% endif %}
If you want to generalise it you can create a list_errors.html which you include in every form template. It handles form and formset errors:
{% if form.errors %}
<div class="alert alert-danger alert-dismissible col-12 mx-1" role="alert">
<div id="form_errors">
{% for key, value in form.errors.items %}
<span class="fieldWrapper">
{{ key }}:{{ value }}
</span>
{% endfor %}
</div>
<button type="button" class="close" data-dismiss="alert" aria-label="Close">
<span aria-hidden="true">×</span>
</button>
</div>
{% elif formset.total_error_count %}
<div class="alert alert-danger alert-dismissible col-12 mx-1" role="alert">
<div id="form_errors">
{% if formset.non_form_errors %}
{{ formset.non_form_errors }}
{% endif %}
{% for form in formset.forms %}
{% if form.errors %}
Form number {{ forloop.counter }}:
<ul class="errorlist">
{% for key, error in form.errors.items %}
<li>{{form.fields|get_label:key}}
<ul class="errorlist">
<li>{{error}}</li>
</ul>
</li>
{% endfor %}
</ul>
{% endif %}
{% endfor %}
</div>
</div>
{% endif %}
form_tags.py
from django import template
register = template.Library()
def get_label(a_dict, key):
return getattr(a_dict.get(key), 'label', 'No label')
register.filter("get_label", get_label)
One caveat: In contrast to forms Formset.errors does not include non_field_errors.
def some_view(request):
if request.method == 'POST':
form = SomeForm(request.POST)
if form.is_valid():
return HttpResponseRedirect('/thanks'/)
else:
form = SomeForm()
return render(request, 'some_form.html', {'form': form})
This answer is correct but has a problem: fields not defined. If you have more then one field, you can not recognize which one has error.
with this change you can display field name:
{% if form.errors %}
{% for field in form %}
{% for error in field.errors %}
<div class="alert alert-danger">
<strong>{{ field.label }}</strong><span>{{ error|escape }}</strong>
</div>
{% endfor %}
{% endfor %}
{% for error in form.non_field_errors %}
<div class="alert alert-danger">
<strong>{{ error|escape }}</strong>
</div>
{% endfor %}
{% endif %}
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