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POWhen and how is a many-to-many relationship created when saving a model?
 

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  1. POWhen and how is a many-to-many relationship created when saving a model?
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    <p>I have a set of document objects and label objects, and I want those two objects to be linked. It's a typical many-to-many relationship. I have the following code:</p> <p>Models.py:</p> <pre><code>class Document(models.Model): title = models.CharField(max_length=50, unique=True) title_slug = models.SlugField(max_length=50, unique=True, editable=False) labels = models.ManyToManyField('Label') def save(self, *args, **kwargs): self.title_slug = slugify(self.title) super(Document, self).save(*args, **kwargs) class Label(models.Model): name = models.CharField(max_length=40, unique=True) slug = models.SlugField(max_length=40, unique=True, editable=False) def save(self, *args, **kwargs): self.slug = slugify(self.name) super(Document, self).save(*args, **kwargs) </code></pre> <p>Views.py:</p> <pre><code>class DocumentForm(ModelForm): class Meta: model = Document fields = ["title","labels"] def upload_document(request): if request.method == 'POST': form = DocumentForm(request.POST, request.FILES) if form.is_valid(): new_document = form.save() return HttpResponseRedirect("/thanks/") else: form = DocumentForm() return render_to_response('upload_page.html', {'form':form}, context_instance=RequestContext(request)) </code></pre> <p>When I upload a document, it gets added to the database, however no labels are being created or associated with the document. Do I need to explicitly add something to the Document's save() function to make this happen? Or somewhere in the Views.py file? I'd imagine it'd go something like:</p> <ul> <li>Check to see if the label that's being added already exists</li> <li>If it doesn't, then create a new label</li> <li>Grab both the current document_id and the new/existing label_id</li> <li>Add a record to the document_labels table (automatically created for the many-to-many relationship)</li> </ul> <p>I feel like that's pretty standard functionality that I assumed would be built in to a many-to-many relationship in django, but it doesn't seem to be working for me so far. I'm trying to avoid reinventing the wheel here. Somewhat new to django.</p> <p>Thanks in advance!</p>
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    1. COAre you using a form? Are you adding `Document`s by other means? What save() method are you talking about? The one in `Document`, `Label` or a form? Please provide some sample view/form/other code that saves the object.
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    2. COI guess I'm not really sure which save method it should go in. Hence my question =] the documents are all being added via a Form on the site. I've updated the question to include that code from views.py
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