In Django forms, it can check whether the form is valid:
if form.is_valid():
return HttpResponseRedirect('/thanks/')
But I'm missing what to do if it isn't valid? How do I return the form with the error messages? I'm not seeing the "else" in any of the examples.
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})
myForm is an instance of either forms.Form or forms.ModelForm, read about Django Forms
UNIQUE constraint failed: exception?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>
messages.error(request, "Error")?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.
This answer is correct but has a problem: fields are not defined. If you have more than one field, you can not recognize which one has the error.
with this change, you can display the 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 %}
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})
@AamirAdnan's answer missing field.label; the other way to show the errors in few lines.
{% if form.errors %}
<!-- Error messaging -->
<div id="errors">
<div class="inner">
<p>There were some errors in the information you entered. Please correct the following:</p>
<ul>
{% for field in form %}
{% if field.errors %}<li>{{ field.label }}: {{ field.errors|striptags }}</li>{% endif %}
{% endfor %}
</ul>
</div>
</div>
<!-- /Error messaging -->
{% endif %}
simply you can do like this because when you initialized the form in contains form data and invalid data as well:
def some_func(request):
form = MyForm(request.POST)
if form.is_valid():
//other stuff
return render(request,template_name,{'form':form})
if will raise the error in the template if have any but the form data will still remain as :
You can put simply a flag variable, in this case is_successed.
def preorder_view(request, pk, template_name='preorders/preorder_form.html'):
is_successed=0
formset = PreorderHasProductsForm(request.POST)
client= get_object_or_404(Client, pk=pk)
if request.method=='POST':
#populate the form with data from the request
# formset = PreorderHasProductsForm(request.POST)
if formset.is_valid():
is_successed=1
preorder_date=formset.cleaned_data['preorder_date']
product=formset.cleaned_data['preorder_has_products']
return render(request, template_name, {'preorder_date':preorder_date,'product':product,'is_successed':is_successed,'formset':formset})
return render(request, template_name, {'object':client,'formset':formset})
afterwards in your template you can just put the code below
{%if is_successed == 1 %}
<h1>{{preorder_date}}</h1>
<h2> {{product}}</h2>
{%endif %}
