How can i create custom validation in django model forms - django

Question

I want to create a custom form validation in Django forms. I am able to do it normal Django forms but unable to do it in model forms.
my Django form code is
class Post_Article(forms.Form):
title = forms.CharField(label = 'Title',max_length = 100)
abstract = forms.CharField(widget = forms.Textarea, max_length = 300)
body = forms.CharField(widget = forms.Textarea)
image = forms.ImageField(required = False)
hash_tags = forms.CharField(max_length = 50,required = False)
def no_of_hash_tags(self):
cleaned_data = super().no_of_hash_tags()
tags = cleaned_data.get('hash_tags')
if tags:
tags = split(str(tags))
if len(tags) > 5:
raise forms.ValiadationError('Maximum 5 tags are allowed')
the Django model is
class PostsArticle(models.Model):
title = models.CharField(max_length=255)
pub_date = models.DateTimeField(default= timezone.now)
abstract = models.TextField()
body = models.TextField()
image = models.ImageField(upload_to=('images/'),blank=True)
user = models.ForeignKey(User , on_delete = models.CASCADE)
hash_tags = models.CharField(max_length = 50,blank= True)
def _str_(self):
return self.title
def get_absolute_url(self):
return reverse('home')
def summary(self):
return self.absract[:200]
def pub_date_pretty(self):
return self.pub_date.strftime('%b %e %Y')
def link_tags(self):
cleaned_data = super().link_tags
tags = cleaned_data.get['hash_tags']
for tag in tags:
hashing(tag,"PostsArticle")
After some discussion on stack overflow I updates my Django forms to
class Post_Article(forms.ModelForm):
title = forms.CharField(label = 'Title',max_length = 100)
abstract = forms.CharField(widget = forms.Textarea, max_length = 300)
body = forms.CharField(widget = forms.Textarea)
image = forms.ImageField(required = False)
hash_tags = forms.CharField(max_length = 50,required = False)
class Meta:
model = PostsArticle
fields=("title", "abstract", "body", "image", "hash_tags")
def clean(self)
:
cleaned_data=super(Post_Article, self).clean()
tags = cleaned_data.get("hash_tags")
if tags:
tags = split(str(tags))
if len(tags) > 5:
raise forms.ValidationError('Maximum 5 tags are allowed')
return cleaned_data
Now I am unable to get how can I use it with my current class used in views.py
class FeedUpdateView(LoginRequiredMixin, UserPassesTestMixin , UpdateView):
model = FeedPosts
fields= ['body', 'image']
template_name= 'post/edit_Feed.html'
def form_valid(self, form):
form.instance.author = self.request.user
return super().form_valid(form)
def test_func(self):
Posts = self.get_object()
if self.request.user == Posts.user:
return True
return False
I want to use my Django forms code instead of creating view from my model directly. I want to do it because I want to have some custom validation of a field as given in my forms code
kindly help how can I add form validation to my model

Answer 1

Cleaning a specific field attribute, you would have to call clean_<field_name>.
class Post_ArticleForm(ModelForm):
class Meta:
model = PostsArticle
fields = ['abstract', 'title', 'body', 'image', 'hash_tags']
def clean_hash_tags(self):
cleaned_data = super().clean_hash_tags()
tags = self.cleaned_data.get('hash_tags')
if tags:
tags = split(str(tags))
if len(tags) > 5:
raise forms.ValiadationError('Maximum 5 tags are allowed')
return cleaned_data

Answer 2

You need to override clean method for your ModelForm.
Example:
class Post_Article(forms.ModelForm):
...
hash_tags = forms.CharField(max_length = 50,required = False)
...
class Meta:
model = PostsArticle
fields=("title", "abstract", "body", "image", "hash_tags",)
def clean(self):
cleaned_data=super(Post_Article, self).clean()
tags = cleaned_data.get("hash_tags")
if tags:
tags = split(str(tags))
if len(tags) > 5:
raise forms.ValidationError('Maximum 5 tags are allowed')
return cleaned_data

Answer 3

the clean funtion is not getting invoked
Django forms is
class Post_Article(forms.ModelForm):
title = forms.CharField(label = 'Title',max_length = 100)
abstract = forms.CharField(widget = forms.Textarea, max_length = 300)
body = forms.CharField(widget = forms.Textarea)
image = forms.ImageField(required = False)
hash_tags = forms.CharField(max_length = 50,required = False)
class Meta:
model = PostsArticle
fields=("title", "abstract", "body", "image", "hash_tags")
def clean(self):
print(hello)
cleaned_data=super(Post_Article, self).clean()
tags = cleaned_data.get("hash_tags")
if tags:
tags = split(str(tags))
if len(tags) > 5:
raise forms.ValidationError('Maximum 5 tags are allowed')
return cleaned_data
the clean funtion is not getting invoked
the formview for the same is
class PostCreateView(LoginRequiredMixin,FormView):
form_class = Post_Article
template_name= 'post/post.html'
success_url = '/'
def form_valid(self, form):
form.instance.user = self.request.user
print(form.instance.user)
return super().form_valid(form)
the formview is in the views.py