Limiting file types for a specific DocumentChooserBlock() Block in Wagtail Steamfield

Question

I'm trying to limit query results for a specific DocumentChooserBlock inside of a wagtail stream field block.

I already know that you can limit file types for DocumentChooser for a page type by using hooks, but I would like to avoid limiting possible file types page wide in case I need them for other StreamField blocks.

Are there any possible ways to implement what I am trying to achieve here?

Answer 1

Using wagtail-generic-chooser offers much more ability to customise the way the Chooser modal works.

Step 1 - Install wagtail-generic-chooser

• Run: pip install wagtail-generic-chooser
• Then add generic_chooser to your project's INSTALLED_APPS.

Step 2 - Set up the Chooser view set

• Similar to the docs instructions on setting up a Chooser view set
• Ensure we can handle the accept parameter by creating a custom class that extends the ModelChooserMixin, this will mean the param still gets passed when searching.
• Add handling of a accept URL param to conditionally filter the returned values.
• Set up a class that extends ModelChooserViewSet which will handle the showing of the Document listing within the modal.

base/views.py

from django.db.models import Q

from generic_chooser.views import ModelChooserMixin, ModelChooserViewSet

from wagtail.documents.models import Document


class RestrictedDocumentChooserMixin(ModelChooserMixin):
    # preserve this URL parameter on pagination / search
    preserve_url_parameters = [
        "accept",
    ]

    def get_unfiltered_object_list(self):
        objects = super().get_unfiltered_object_list()

        accept = self.request.GET.get("accept")
        print("get_unfiltered_object_list", accept)

        if accept:
            accepted_files = accept.split(",")

            queries = [Q(file__iendswith=f".{value}") for value in accepted_files]

            query = queries.pop()
            for item in queries:
                query |= item

            objects = objects.filter(query)
        return objects


class RestrictedDocumentChooserViewSet(ModelChooserViewSet):
    chooser_mixin_class = RestrictedDocumentChooserMixin

    icon = "doc"
    model = Document
    page_title = "Choose a document"
    per_page = 10
    order_by = "title"
    fields = ["title", "file"]

Step 3 - Create the Chooser Widget

• This widget is not the Block but will be used as the base for the Block and can also be used for a FieldPanel.
• Similar to the Setting up of a model based Widget create a class that extends the AdminChooser.
• In the __init__ method we pull out the accept kwarg so we can use it to generate the custom URL param.
• Override the get_edit_item_url method which will allow the clicking of a selected Document to edit it.
• Override the ``get_choose_modal_urlto append the URL query param (note: I could not getreverse` working here without heaps more wrangling).

base/models.py

from django.contrib.admin.utils import quote
from django.urls import reverse

from generic_chooser.widgets import AdminChooser

from wagtail.documents.models import Document


class RestrictedDocumentChooser(AdminChooser):
    def __init__(self, **kwargs):

        self.accept = kwargs.pop("accept")

        super().__init__(**kwargs)

    choose_one_text = "Choose a Document"
    choose_another_text = "Choose another document"
    link_to_chosen_text = "Edit this document"
    model = Document
    choose_modal_url_name = "restricted_document_chooser:choose"

    def get_choose_modal_url(self):
        url = super().get_choose_modal_url()
        return url + "?accept=%s" % self.accept

    def get_edit_item_url(self, item):
        return reverse("wagtaildocs:edit", args=[item.id])

Step 4 - Register the chooser viewset in Wagtail Hooks

• No need to use the construct_document_chooser_queryset here, instead use the hook register_admin_viewset and register the RestrictedDocumentChooserViewSet.

base/wagtail_hooks.py

from wagtail.core import hooks
from .views import RestrictedDocumentChooserViewSet

# ... other hooks etc

@hooks.register("register_admin_viewset")
def register_restricted_document_chooser_viewset():
    return RestrictedDocumentChooserViewSet(
        "restricted_document_chooser", url_prefix="restricted-document-chooser"
    )

Step 5 - Set up and use the custom Block

• This class extends the ChooserBlock and wraps the RestrictedDocumentChooser widget that has been created.
• On __init__ the same kwarg accept is pulled out and passed to the RestrictedDocumentChooser when created.
• This block can be used by calling it similar to any other block, with the kwarg accept though. doc_block = RestrictedDocumentChooserBlock(accept="svg,md")

base/blocks.py

from django.utils.functional import cached_property
from wagtail.images.blocks import ChooserBlock

# ...

class RestrictedDocumentChooserBlock(ChooserBlock):
    def __init__(self, **kwargs):
        self.accept = kwargs.pop("accept")
        super().__init__(**kwargs)

    @cached_property
    def target_model(self):
        from wagtail.documents.models import Document

        return Document

    @cached_property
    def widget(self):
        from .widgets import RestrictedDocumentChooser

        return RestrictedDocumentChooser(accept=self.accept)

    def get_form_state(self, value):
        return self.widget.get_value_data(value)