Django ManyToManyField Persistence Fails - django

Question

I have a simple Django 3.1.0 app I need to create in order to assign Tasks with Tags (or assign tags into tasks).
My Model
class Task(models.Model):
user = models.CharField(max_length=33)
time = models.DateTimeField(auto_now_add=True)
task = models.CharField(max_length=500)
tags = models.ForeignKey('Tag', on_delete=models.SET_NULL, null=True)
class Tag(models.Model):
tag = models.CharField(max_length=30, default="No Tag")
members = models.ManyToManyField('Task')
class Meta:
verbose_name = "tag"
verbose_name_plural = "tags"
My Form
class TaskForm(ModelForm):
class Meta:
model = Task
fields = ['user', 'task', 'tags']
template_name = 'tasks.html'
tags = ModelMultipleChoiceField(
queryset=Tag.objects.values().all(), widget=CheckboxSelectMultiple()
)
My View
def main(request):
model = Task.objects.values().all()
form = TaskForm()
con = {'context': list(model), 'form': form}
if request.method == 'POST':
form = TaskForm(request.POST)
if form.is_valid():
obj = form.save(commit=False)
form.save_m2m()
return redirect('/')
else:
form = TaskForm()
return render(request, "tasks.html", con)
The migrations are successfull, and with the above code, the view shows a checkbox list with the fetched tags, but the problem is that when I hit Submit on the form, the values are not saved/written on the database but the page reloads successfully.
However, if I turn the following:
obj = form.save(commit=False)
form.save_m2m()
into
form.save(commit=True)
#form.save_m2m()
the values are written only from the fields 'user', 'task' - without the 'tags'
It's also funny that what fetches back on the webpage as values of the tags is in the shape of:
[checkbox] {'id': 1, 'tag': 'aks'}
What am I doing wrong? Thanks.
UPDATE after a comment below:
As Abdul Aziz suggested, I had to remove the values() from the queryset. But after that , to make it work, I had to add also:
In the model:
tag = models.CharField(max_length=100, default="No Tags")
and then refer to that one in the form and Vue template.

Answer 1

You have a ForeignKey set to the Tag model on your Task model, when you actually want a ManyToMany relationship between them. Remove the foreign key and set a related_name to the ManyToManyField in the Tag model like so:
class Task(models.Model):
user = models.CharField(max_length=33)
time = models.DateTimeField(auto_now_add=True)
task = models.CharField(max_length=500)
class Tag(models.Model):
tag = models.CharField(max_length=30, default="No Tag")
members = models.ManyToManyField('Task', related_name="tags")
class Meta:
verbose_name = "tag"
verbose_name_plural = "tags"
Also in your form you have:
tags = ModelMultipleChoiceField(
queryset=Tag.objects.values().all(), widget=CheckboxSelectMultiple()
)
Why are you using values here? Remove it:
tags = ModelMultipleChoiceField(
queryset=Tag.objects.all(), widget=CheckboxSelectMultiple()
)