I'm practicing with Django's FormViews.
In this app, I'm creating a PostCreate view that creates a blog post.
Here are my codes:
models.py
class Post(models.Model):
user = models.ForeignKey(User)
post_title = models.CharField(max_length=200)
post_content = models.CharField(max_length=500)
class Tag(models.Model):
name = models.CharField(max_length=64, unique=True)
posts = models.ManyToManyField(Post)
forms.py
class PostForm(forms.ModelForm):
post_title = forms.CharField(
label=u'Title',
widget=forms.TextInput(attrs={'size':64})
)
post_content = forms.CharField(
label=u'Content',
widget=forms.TextInput(attrs={'size':128})
)
tags = forms.CharField(
label=u'Tags',
required=True,
widget=forms.TextInput(attrs={'size':64})
)
class Meta:
model = Post
exclude = ('user', 'post_date')
views.py
class PostCreate(CreateView):
template_name = 'app_blog/post_save_form.html'
model = Post
form_class = PostForm
def form_valid(self, form):
self.object = form.save(commit=False)
self.object.user = self.request.user
tag_names = form.cleaned_data['tags'].split()
for tag_name in tag_names:
tag, dummy = Tag.objects.get_or_create(name=tag_name)
self.object.tag_set.add(tag)
return super(PostCreate, self).form_valid(form)
When I try saving a post (Test Post 1) into a database, it gives me an error:
needs to have a value for field "post" before this many-to-many relationship can be used.
It looks like the problem is caused by lines in views.py where I split the "tag" field and add the tags to the post object's tag_set field. I suppose this logic should not be included in the form_valid method... but I don't know where else this should be implemented..
Any help would be greatly appreciated :) Thanks
No, that's not what the problem is. The problem is that you haven't saved the Post object yet, so you can't create a many-to-many relationship with it (because under the hood, m2m is just a linking table with foreign keys to both entities). The solution is to save self.object
first.
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