How can I edit manytomanyfield data - html

Question

I am trying to edit manytomanyfield data. Here is my model
class Permission(models.Model):
shop = models.ForeignKey(Shop, on_delete=models.SET_NULL, null=True)
permission_title = models.CharField(max_length=255)
class Meta:
ordering = ["-id"]
def __str__(self):
return self.permission_title
class Roles(models.Model):
shop = models.ForeignKey(Shop, on_delete=models.SET_NULL, null=True)
role_title = models.CharField(max_length=255)
permissions = models.ManyToManyField(Permission)
class Meta:
ordering = ["-id"]
def __str__(self):
return self.role_title
Here in these models i have a model called permission. this model is in a manytomanyfield relation with Roles model. I want to edit this manytomanyfield. I have already did the creation part. But now i want to edit the data and I want to show the data in the templates, I chose while creating a role. I want to show it an input type checkox
Here is my views:-
def createRolesView(request, shop_id):
shopId = get_object_or_404(Shop, pk=shop_id)
permissions = Permission.objects.filter(
shop=shopId.id
)
if shopId.user == request.user:
if request.method == "POST":
role_title = request.POST.get("role_title")
shop = Shop.objects.get(id=shopId.id)
permissions = request.POST.getlist("permissions")
rl = Roles(
role_title = role_title,
shop = shop,
)
rl.save()
for p in permissions:
rl.permissions.add(p)
rl.save()
return redirect(f"/adminpanel/roles/{shopId.id}/")
args = {
"shopId": shopId,
"permissions": permissions,
}
return render(request, "roles/create-role.html", args)
else:
return redirect("warning")
def editRolesView(request, role_id, shop_id):
shopId = get_object_or_404(Shop, pk=shop_id)
roleId = get_object_or_404(Roles, pk=role_id)
if shopId.user == request.user:
if request.method == "POST":
roleId.role_title = request.POST.get("role_title")
shop = Shop.objects.get(id=shopId.id)
# roleId.permissions_set.all()
args = {
"shopId": shopId,
"roleId": roleId,
}
return render(request, "roles/edit-role.html", args)
else:
return redirect("warning")

Answer 1

Suggestions only, I haven't coded this myself.
[Edit. This question caused an "itch", so I coded it up to conform I was right. Skip ahead for a pretty generic edit M2M view ]
Two simple tables
One showing the current permissions assigned to the role, which has the queryset roles.permissions.all(), along with a "remove" checkbox for each.
The other showing the available permissions with an "add" checkbox for each. The queryset might be permissions.exclude( roles__pk=this_role.pk) (to exclude those already added, although it's harmless to add something already added). You should also exclude any permissions which this roles instance is not allowed to acquire.
You might use Django Formsets, but it's also rather easy to process raw data from request.POST in this case. Your template would basically be a form containing instances of
<input type="checkbox" name="add" value="{{permission.pk}}" >
and
<input type="checkbox" name="remove" value="{{permission.pk}}" >
with appropriate descriptive text gathered from the permission instance.
If it were me I'd display them as tables left and right, but as long as they are inside a <form> with Submit (and Done?) buttons, it's not relevant.
In your POST handling, you'd get the checked pk values with request.POST.getlist('add') and request.POST.getlist('remove'). For each one, revalidate that it was in the original queryset that was rendered into a form, and if the pk values are acceptable
role.permissions.add( permission) # or .remove( permission)
(where permission is the Permissions instance that's been revalidated)
After Submit of the above you'd probably redirect back to the same again so that the user can see that the requested additions and removals have happened. The "Done" button will redirect elsewhere( if "Done" in request.POST ... )
[Edit] The result of causing me an itch I had to scratch ....
class GenericEditM2MView( DetailView):
#model = Model # required as per DetailView
# template_name = # as per DetailView
#m2m_fieldname = None # no longer required if unique: the name of the model's m2m field to operate on
remove_qs = None # defaults to .all() of the m2m field
success_url = '.' # defaults to displaying the modified m2m relationship unless done
done_url = None # where to go if submit="Done", defaults to success_url
"""
template_name must define a form full of checkboxes, obtained from
{% for p in add_qs %}
<input type="checkbox" name="add" value="{{p.pk}}" > {% endfor}
{% for p in remove_qs %}
<input type="checkbox" name="remove " value="{{p.pk}}" > {% endfor}
default is to return to this same view after submit, to show that the changes
have been made. You can supply <input type="submit" name="submit" value="done" />
which will go to done_url instead of success_url
example use:
class PenStockM2MView( GenericEditM2MView):
template_name = 'playpen/edit_m2m.html'
model = PenStock
# m2m_fieldname = 'name' # works it out if ony one M2M field on the model
done_url = '/playpen/OK'
"""
def __init__(self, **kwargs):
super().__init__(**kwargs)
# everything works without this __init__ provided self.m2m_fieldname is present and correct.
# if model has only one m2m field, locate it via _meta as default.
# Also check m2m_fieldname is m2m because very confusing errors later if it's not!
f = getattr(self, 'm2m_fieldname', None)
m2m_fieldnames = [ field.name for field in self.model._meta.get_fields() if field.many_to_many ]
model_name = self.model.__name__
if f and not f in m2m_fieldnames:
raise AttributeError( f'field "{f}" is not a many-to-many field in {model_name}')
if not f:
if len( m2m_fieldnames ) == 1:
self.m2m_fieldname = m2m_fieldnames[0]
else:
raise AttributeError( f'Cannot identify a unique many-to-many field in {model_name}' )
def get_add_queryset(self):
field = getattr( self.object, self.m2m_fieldname)
remove_qs = self.get_remove_queryset()
already_there = remove_qs.values_list('pk', flat=True)
return remove_qs.model.objects.exclude( pk__in = already_there) # is qs.model documented?
def get_remove_queryset(self):
if hasattr( self, 'remove_queryset'):
return self.remove_qs
remove_qs = getattr( self.object, self.m2m_fieldname)
return remove_qs.all()
def get_context_data( self, **kwargs):
context = super().get_context_data( **kwargs)
context['add_qs'] = self.get_add_queryset()
context['remove_qs'] = self.get_remove_queryset()
return context
def post( self, request, *args, **kwargs):
self.object = self.get_object()
add = request.POST.getlist('add')
remove = request.POST.getlist('remove')
add_objs = list( self.get_add_queryset().filter(pk__in=add) )
remove_objs = list( self.get_remove_queryset().filter(pk__in=remove) )
field = getattr( self.object, self.m2m_fieldname )
field.add( *add_objs)
field.remove( *remove_objs)
return HttpResponseRedirect( self.get_done_url() or self.get_success_url() )
def get_success_url(self):
return self.success_url
def get_done_url( self):
done = self.request.POST.get("submit", None)
if done == "done" and hasattr(self, 'done_url'):
return self.done_url
return None
And here's a template (not completely generic. Using Bootstrap in base.html.)
<div class="row">
<div class="col-md-3 col-sm-4 col-xs-6">
<h1> Remove </h1>
<table class="table tbl">
{% for p in remove_qs %}
<tr><td>{{p.name }}</td><td><input type="checkbox" name="remove" value="{{p.pk}}" form="the-form" class="BigCheckbox"></td></tr>
{%endfor %}
</table>
</div>
<div class="col-md-3 col-sm-4 col-xs-6">
<h1> Add </h1>
<table class="table tbl">
{% for p in add_qs %}
<tr><td>{{p.name }}</td><td><input type="checkbox" name="add" value="{{p.pk}}" form="the-form" class="BigCheckbox"></td></tr>
{%endfor %}
</table>
</div>
</div>
<div class="row">
<form method="post" id="the-form"> {% csrf_token %}
<input type="submit" name="submit" value="submit" />
 
<input type="submit" name="submit" value="done" />
</form>
</div>