Is it possible to pass parameter to a form __init__ in a collection?

[lallulli]

I have a form class contained in a FormCollection.

My form has an __init__ method which expects additional parameters, such as the request object. How can I pass the request object to the form, provided that the form is created by the FormCollection code behind the scenes? In vanilla Django, I would use the get_form_kwargs method of my FormView class view.

Thank you!

[jrief]

Does this method help to solve your use-case?

[boosh]

I have the same question. I see get_collection_kwargs allows me to pass kwargs from the view to the collection form, but there doesn't seem to be a way of passing those kwargs from the collection to individual child forms. Even adding a dedicated setter on the child form and calling it in __init__ on the collection doesn't work because it seems the form attribute gets deleted. I.e.:

class WizardForm(FormCollection):

    default_renderer = FormRenderer(
        field_css_classes="mb-3",
        fieldset_css_classes="border-2 rounded p-3 mb-3",
    )
    main_form = MainForm()
    blog_post = BlogPostForm()

    def __init__(self, *args, **kwargs):
        project = kwargs.pop('project')
        super().__init__(*args, **kwargs)
        self.blog_post.set_kwargs(project=project)

Gives an error:

'WizardForm' object has no attribute 'blog_post'

Also, instantiating blog_post in the collection's __init__ method means the form is never rendered.

Is there a way to directly pass collection kwargs to a form constructor or something like set_form_kwargs?

Thanks

[boosh]

Ah, I've just discovered I can reach into the holder dict. This works:

class WizardView(FormCollectionView):
    template_name = "core/wizards/create.html"
    collection_class = WizardForm
    success_url = "/"

    def get_collection_kwargs(self):
        kwargs = super().get_collection_kwargs()
        kwargs["project"] = get_current_project(self.request)
        return kwargs


class WizardForm(FormCollection):
    default_renderer = FormRenderer(
        field_css_classes="mb-3",
        fieldset_css_classes="border-2 rounded p-3 mb-3",
    )
    main_form = MainForm()
    blog_post = BlogPostForm()

    def __init__(self, *args, **kwargs):
        project = kwargs.pop('project')
        super().__init__(*args, **kwargs)
        self.declared_holders["blog_post"].set_kwargs(project=project)

[nicokant]

I'm having the same problem, but it seems that the method set_kwargs does not exists.

Would it be possible to define the holders just by classes, instead of defining them as class instances?
This way it would be possible to provide a method get_holder_kwargs to inject values down in the form hierarchy in a django compatible way? Right now the library is great, but I feel there is some friction with the django forms api.

My use case is the following:
I have a bulk list of items that I need to edit/create using a FormCollection, the items depend on an order, but the order is not part of the form. I need to pass the order in the init of each form because it's used to pre-filter some modelchoicefield queryset.

[jrief]

Could you please create an example of that Form and your FormCollection. Currently I don't understand what you want to achieve.

Would it be possible to define the holders just by classes, instead of defining them as class instances?

The holder instances must be replicated with slightly different values when creating the collection siblings. Therefore I do not see a solution for this.

[nicokant]

Hi,
I managed to find a solution to that, I'm basically modifing the forms in the holder after init.
Here is some of the code that I used, the complete code is here: https://github.com/NINAnor/genlab_bestilling/blob/main/src/genlab_bestilling/forms.py

# url: /order/<int:pk>/items/
class OrderItemQuantityUpdateView(BulkEditCollectionView):
    collection_class = ItemQuantityCollection
    model = OrderItemQuantity

   # make sure to inject the url kwargs into the collection
    def get_collection_kwargs(self):
        kwargs = super().get_collection_kwargs()
        kwargs["context"] = {"order_id": self.kwargs["pk"]}
        return kwargs

    def get_initial(self):
        collection_class = self.get_collection_class()
        queryset = self.get_queryset()
        initial = collection_class(
            context={"order_id": self.kwargs["pk"]}
        ).models_to_list(queryset)
        return initial

# forms.py
class OrderItemQuantityForm(forms.ModelForm):
    id = forms.IntegerField(required=False, widget=forms.widgets.HiddenInput)
    
    # custom method, will be called after __init__, but before rendering the form
    def reinit(self, context):
        self.order_id = context["order_id"]
        order = Order.object.get(id=self.order_id)
        # pre-filter the available options, based on a relationship 
        self.fields["item"].queryset = OrderItem.objects.filter(type=order.type)

    # inject the order_id into the save method
    def save(self, commit=True):
        obj = super().save(commit=False)
        obj.order_id = self.order_id
        if commit:
            obj.save()
            self.save_m2m()
        return obj

    class Meta:
        model = OrderItemQuantity
        fields = ("id", "item", "quantity")
        widgets = {
            "item": Selectize(search_lookup="name_icontains"),
        }


# NOTE: the collection here is just an array of model instances, all the instances are related to an order but it's not modified in this form
class ItemQuantityCollection(FormCollection):
    min_siblings = 1
    add_label = "Add item"
    items = OrderItemQuantityForm()
    default_renderer = FormRenderer(field_css_classes="mb-3")

    def __init__(self, *args, context=None, **kwargs):
        super().__init__(*args, **kwargs)
        self.context = context or {}

        for name, holder in self.declared_holders.items():
            if name == "items":
                # this is just to keep the logic in the original form
                holder.reinit(self.context)

    def retrieve_instance(self, data):
        if data := data.get("items"):
            try:
                return OrderItemQuantity.objects.get(id=data.get("id") or -1)
            except (AttributeError, OrderItemQuantity.DoesNotExist, ValueError):
                return OrderItemQuantity(
                    item_id=data.get("item"),
                    quantity=data.get("quantity"),
                )