add partialDelete to button actions

assets/tag-attributes.pegjs

@@ -106,6 +106,9 @@ Function
   = 'setFieldValue' _ '(' _ target:PATH _ ',' _ source:SOURCEARG _ ')' {
     return { funcname: 'setFieldValue', args: [target.split('.'), source] };
   }
+  / 'deletePartial' _ '(' _ target:PATH _ ',' _ source:SOURCEARG _ ')' {
+    return { funcname: 'deletePartial', args: [target.split('.'), source] };
+  }
   / _ funcname:$keystring '(' args:arglist ')' _ {
     return { funcname: funcname, args: args };
   }

client/django-formset/DjangoFormset.ts

@@ -884,7 +884,7 @@ class DjangoButton {
 	}
 
 	/**
-	 * Action to activate a button so that it can be used
+	 * Action to activate a button so that it can be used by dialogs.
  	 */
 	private activate(...args: any[]) {
 		return (response: Response) => {
@@ -903,6 +903,15 @@ class DjangoButton {
 		}
 	}
 
+	private deletePartial(target: Path, source: FieldValue) {
+		return (response: Response) => {
+			if (typeof source === 'string' && parseInt(source)) {
+				this.formset.deletePartial(target, source);
+			}
+			return Promise.resolve(response);
+		}
+	}
+
 	/**
 	 * Dummy action to be called in case of empty actionsQueue.
  	 */
@@ -2201,6 +2210,36 @@ export class DjangoFormset {
 		}
 	}
 
+	async deletePartial(path: Path, pk: string) : Promise<Response|undefined> {
+		if (!this.endpoint)
+			throw new Error("<django-formset> requires attribute 'endpoint=\"server endpoint\"' for submission");
+		try {
+			const query = new URLSearchParams({pk, path: path.join('.')});
+			const headers = new Headers();
+			if (this.CSRFToken) {
+				headers.append('X-CSRFToken', this.CSRFToken);
+			}
+			const response = await fetch(`${this.endpoint}?${query.toString()}`, {
+				method: 'DELETE',
+				headers,
+			});
+			switch (response.status) {
+				case 204:
+					this.clearErrors();
+					return response;
+				default:
+					console.warn(`Unknown response status: ${response.status}`);
+					this.clearErrors();
+					this.buttons.forEach(button => button.restoreToInitial());
+					return response;
+			}
+		} catch (error) {
+			this.clearErrors();
+			this.buttons.forEach(button => button.restoreToInitial());
+			alert(error);
+		}
+	}
+
 	private reportErrors(body: any) {
 		console.info("Response from server:", body);
 		for (const form of this.forms) {

formset/views.py

@@ -4,7 +4,7 @@
 from django.db import transaction
 from django.db.models import QuerySet
 from django.forms.fields import CallableChoiceIterator
-from django.http.response import HttpResponseBadRequest, JsonResponse
+from django.http.response import HttpResponse, HttpResponseForbidden, HttpResponseBadRequest, JsonResponse
 from django.utils.encoding import force_str
 from django.utils.functional import cached_property
 from django.views.generic.base import ContextMixin, TemplateResponseMixin, View
@@ -206,6 +206,14 @@ def patch(self, request, **kwargs):
         """
         return self.post(request, **kwargs)
 
+    def delete(self, request, **kwargs):
+        """
+        Method `DELETE` is used for partial deletion.
+        """
+        if set(['path', 'pk']).issubset(request.GET):
+            return self._delete_partial()
+        return HttpResponseForbidden("Method DELETE not supported in this context")
+
     def _fetch_partial_data(self):
         collection_class = self.get_collection_class()
         empty_holder = collection_class
@@ -225,6 +233,22 @@ def _fetch_partial_data(self):
                 return JsonResponse(initial)
         return HttpResponseBadRequest("Invalid path value")
 
+    def _delete_partial(self):
+        collection_class = self.get_collection_class()
+        empty_holder = collection_class
+        for part in self.request.GET['path'].split('.'):
+            if not (empty_holder := empty_holder.declared_holders.get(part)):
+                break
+        if empty_holder is not None:
+            try:
+                instance = empty_holder._meta.model.objects.get(pk=self.request.GET.get('pk'))
+            except empty_holder._meta.model.DoesNotExist:
+                pass
+            else:
+                instance.delete()
+                return HttpResponse(status=204)
+        return HttpResponseBadRequest("Invalid path value")
+
     def get_context_data(self, **kwargs):
         context = super().get_context_data(**kwargs)
         context['form_collection'] = self.get_form_collection()

testapp/tests/test_e2e_dialogmodel.py

@@ -68,18 +68,22 @@ class PageForm(ModelForm):
         required=False,
     )
     edit_reporter = Activator(
-        label="Edit Reporter",
         widget=Button(
             action='activate("prefill", page.reporter)',
             attrs={'df-disable': '!page.reporter'},
         ),
     )
     add_reporter = Activator(
-        label="Add Reporter",
         widget=Button(
             action='activate',
         ),
     )
+    delete_reporter = Activator(
+        widget=Button(
+            action='deletePartial(change_reporter, page.reporter) -> setFieldValue(page.reporter, "")',
+            attrs={'df-disable': '!page.reporter'},
+        ),
+    )
 
     class Meta:
         model = PageModel
@@ -196,3 +200,29 @@ def test_edit_reporter(page, mocker, viewname):
     assert Reporter.objects.get(id=reporter.id).full_name == "Sarah Johnson"
     expect(select_reporter).to_have_value(str(reporter.id))
     expect(pseudo_input).to_have_text("Sarah Johnson")
+
+
+@pytest.mark.urls(__name__)
+@pytest.mark.parametrize('viewname', ['page'])
+def test_delete_reporter(page, mocker, viewname):
+    form_collection = page.locator('django-formset > django-form-collection')
+    dialog = form_collection.nth(0).locator('> dialog')
+    expect(dialog).not_to_be_visible()
+    select_reporter = form_collection.locator('select[name="reporter"]')
+    expect(select_reporter).to_have_value('')
+    reporter, _ = Reporter.objects.get_or_create(full_name="Sarah Hemingway")
+    select_reporter.evaluate(f'el => el.value = {reporter.id}')
+    expect(select_reporter).to_have_value(str(reporter.id))
+    pseudo_input = form_collection.nth(1).locator(f'.ts-wrapper div.item[data-value=\"{reporter.id}\"]')
+    expect(pseudo_input).to_have_text("Sarah Hemingway")
+
+    # delete the current reporter remotely
+    spy = mocker.spy(PageCollectionView, 'delete')
+    form_collection.nth(1).locator('button[name="delete_reporter"]').click()
+
+    # check if the reporter was deleted from the database and from the selectize widget
+    sleep(1)
+    spy.assert_called()
+    assert not Reporter.objects.filter(id=reporter.id).exists()
+    expect(select_reporter).to_have_value('')
+    expect(pseudo_input).not_to_be_visible()