How to override FileField and automatically delete previous file in Django? - django

Question

im django beginner (django 1.2.5)
I have that model:
class Document(models.Model):
file = models.FileField(upload_to='documents/%Y/%m/%d', null=True, blank=True)
title = models.CharField(max_length=30)
created = models.DateTimeField(auto_now_add=True)
modified = models.DateTimeField(auto_now=True)
author = models.ForeignKey(User)
#other fields
#other fields
and model form to this:
class DocumentForm(ModelForm):
file = forms.FileField(required=True, error_messages={'required' : 'required!','empty': "empty!"})
title = forms.CharField(widget = forms.TextInput(attrs={'size': 93,}), error_messages={'required': 'required!'})
#other fields
#other fields
class Meta:
model = Document
exclude = ('author',)
def save(self, author, commit=True):
document=ModelForm.save(self,commit=False)
document.author = author
if commit:
document.save()
return document
I uploading new documents in using DocumentForm above and it works pretty but when i trying edit some document i cannot put new file in place previous. I may change every field except FileField.
def document_edit(request, document_id):
doc = get_object_or_404(Document, id=document_id)
form = DocumentForm(instance=doc)
if doc.author == request.user:
if request.method == "POST":
form = DocumentForm(request.POST, request.FILES, instance=doc)
if form.is_valid():
if request.POST.get('cancel'):
return HttpResponseRedirect('/')
elif request.POST.get('delete'):
document = Document.objects.get(id=document_id)
document.file.delete()
document.delete()
return HttpResponseRedirect('/')
else:
form.save(author=request.user)
return HttpResponseRedirect('/')
else:
# return again form with errors
else:
# return form with doc instance
else:
# return "you can't edit this doc!"
I research django documentation and i only know i should write some custom save method in some class but i completely have no idea how can i do this. It should be save() method in Document() or in DocumentForm()?
Generally i want this: When i put path to new file in form i want override this new file in his place and automatically delete previous file.
Can you help me? Thanks in advance!

Answer 1

You are on the right track, you just want to use the instance keyword, so your form reflects the object being edited. Simplified version:
def edit_upload(request, document_id):
doc = get_object_or_404(Document, id=document_id)
if request.method == 'POST': # If the form has been submitted...
form = DocumentForm(request.POST, request.FILES, instance=doc)
if form.is_valid(): # All validation rules pass
if doc.file: # If document has file already...
doc.file.delete() # delete it
form.save() # Saves object, uses new uploaded file
return redirect('/thanks/') # Redirect after success
else:
form = DocumentForm(instance=doc) # Show form to edit
return render(request, 'edit.html', {
'form': form,
})