Django is_valid() throws ValueError when submitting a form. Not sure why

StackOverflow https://stackoverflow.com/questions/5370874

Pergunta

The following code creates a form based on a model, Post. Problem I am facing is that the form never validates and gives ValueError that data did not validate if I remove the if post_form.is_valid(): check.

However, if I keep the code as shown below, that is, I keep the if post_form.is_valid(): check, then it always fails and the else block is executed.

I was trying to save the User, which is a ForeignKey to Django's Auth, in my model and it turns out I cannot even get past this vlaidation error.

Any help will be appreciated. Thanks.

#----------------------------Model-------------------------------------- 
class Post (models.Model): 
    name = models.CharField(max_length=1000, help_text="required, name of the post") 
    user = models.ForeignKey(User, unique=False, help_text="user this post belongs to") 

    def __unicode__(self): 
        return self.name 

class PostForm(ModelForm): 
    class Meta: 
            model = Post 
#----------------------------./Model--------------------------------------

#----------------------------View-------------------------------------- 
@login_required 
def create_post (request): 
    if request.method == 'POST': 
        post_form = PostForm(request.POST) 
        if post_form.is_valid(): 
            post.save() 
            return render_to_response('home.html') 
        else: 
            return HttpResponse('not working') 
    else: 
        post_form = PostForm() 
        return render_to_response('create.html', {'post_form':post_form }) 
#----------------------------./View--------------------------------------

#----------------------------./Template--------------------------------------
<html lang="en">
<head>
    <meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<title>home</title>
</head>
<body>
<form method="POST" action='.'>{% csrf_token %}
    <p>{{post_form.name.label_tag}}</p>
    <p>{{post_form.name}}</p>
        <p><input type="submit" value="Submit"/></p>
</form>
</body>
</html>
#----------------------------./Template--------------------------------------
Foi útil?

Solução

In your other post, you were trying to automatically insert the user field, which probably means you don't have a user field displayed in the template.

Exclude it if you plan to insert the user anyways.

class PostForm(ModelForm): 
    class Meta: 
            model = Post 
            exclude = ('user',) # exclude this

if request.method == 'POST': 
    post_form = PostForm(request.POST) 
    if post_form.is_valid(): 
        post = post.save(commit=False) 
        post.user = request.user
        post.save()  # now post has a user, and can actually be saved.
        return render_to_response('home.html')

Outras dicas

It shows not valid, because the form is not valid. Presumably whoever submitted the form did not fill in the required fields. If you display the value of form.errors you will see why.

Alternatively, although we have to guess because you have not shown the template, you have not included all the required fields in the template itself, therefore the form will never be valid.

Remove the first else clause with its HttpResponse. The view will then default to showing the form again, complete with errors.

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