How can i limit number of tags that could be related to item?

I need to limit number of tags than can be related to it开发者_运维知识库em. It always should be max 5 tags.

        tags = form.cleaned_data['tags']
        item.tags = tags
        item.save()  

I think it is a good idea to do this in clean method of form

class MyForm(forms.Form)
    ...

    def clean_tags(self):
       tags=  self.cleaned_data['tags']
       if len(tags.split(" ")) > 5:
          raise forms.ValidationError("you can only add 5 tags")
       return tags

EDIT This will be checked when you will call form.is_valid(). When error occurs it is added to form.tags.errors

EDIT

so just

return tags.split(" ")[:5]

Assuming tags is a set or list ?!

tags = form.cleaned_data['tags']
if len(tags) < 5:
    item.tags = tags
    item.save()
else:
    print "Oopsy"

Humm you want

tags = form.cleaned_data['tags']
item.tags = tags[:5]
item.save()