Django doesn't show ValidationError in my web-site - django

Question

guys, I am beginner at Django. I watch lessons on youtube and get different results. I use Django==2.0.7 and Python==3.6.5.
I try to get error on my page, if I write not correct name of title, but I don't get it. Look at func - **def clean_title(self, *args, kwargs), I hope, you understand, what I mean. There I have "raise forms.ValidationError("Error")", but it doesn't work anymore.
forms.py
from django import forms
from .models import Product
class ProductForm(forms.ModelForm):
title = forms.CharField(label='',
widget=forms.TextInput(attrs={"placeholder": "title"}))
Description = forms.CharField(
required=False,
widget=forms.Textarea(
attrs={
"placeholder": "Your description",
"class": "new-class-name two",
"id": "new-class-name two",
"rows": 20,
'cols':120
}
)
)
Price = forms.DecimalField(initial=199.99)
class Meta:
model = Product
fields = [
'title',
'Description',
'Price'
]
def clean_title(self, *args, **kwargs):
title = self.cleaned_data.get('title')
if "Ruslan" in title:
return title
else:
raise forms.ValidationError("Error")
In forms.py I created class ProductForm and declared the fields. In my page I see it.
Also I defined clean_title. I wanted to get error if I filled in wrong name of title.
views.py
from django.shortcuts import render
from .models import Product
from .forms import ProductForm as CreateForm, PureDjangoForm
def create_form(request):
form = CreateForm(request.POST or None)
if form.is_valid():
form.save()
form = CreateForm()
context = {
'form': form
}
return render(request, "create_product_form.html", context)
create_product_form.html
{% extends 'base.html' %}
{% block content %}
<form action='.' method="POST"> {% csrf_token %}
{{ form.as_p }}
<input type='submit' value='Save' />
</form>
{% endblock %}
This is my file.html, it inherits any not important details from base.html.
Guys, what's wrong, help me, please, I can't understand how I can get error if name of title is not correct? I see all fields on my page and I can fill in it, but it doesn't show me errors.

Answer 1

You should not create a new form if you made one that is invalid, the view thus should look like:
def create_form(request):
if request.method == 'POST':
form = CreateForm(request.POST, request.FILES)
if form.is_valid():
form.save()
return redirect('name-of-some-view')
else:
form = CreateForm()
context = {
'form': form
}
return render(request, 'create_product_form.html', context)
Note: In case of a successful POST request, you should make a redirect
[Django-doc]
to implement the Post/Redirect/Get pattern [wiki].
This avoids that you make the same POST request when the user refreshes the
browser.