✨ [#4930] Implement the actual export

Export submission statistics based on the timeline logs.

Note: if the timeline logs are pruned, this affects the exports. It's
up to the users to periodically create these exports and save them
somewhere if they periodically prune log records.

Note 2: filtering on forms only works on new log records, as existing
log records don't have the form ID stored in the structured data.

Submissions that were deleted for which existing log records are
present will display 'unknown' for some columns because the relevant
information has been deleted. Only from 3.0 onwards are we snapshotting
the data required for the exports.

src/openforms/forms/admin/views.py

@@ -1,4 +1,5 @@
 import zipfile
+from datetime import date
 from uuid import uuid4
 
 from django import forms
@@ -8,14 +9,16 @@
 from django.contrib.auth.mixins import LoginRequiredMixin, PermissionRequiredMixin
 from django.contrib.messages.views import SuccessMessageMixin
 from django.contrib.postgres.forms import SimpleArrayField
-from django.http import FileResponse
+from django.http import FileResponse, HttpResponse
 from django.shortcuts import get_object_or_404
 from django.urls import reverse_lazy
 from django.utils.decorators import method_decorator
+from django.utils.http import content_disposition_header
 from django.utils.translation import gettext_lazy as _
 from django.views import View
 from django.views.generic.edit import FormView
 
+from import_export.formats.base_formats import XLSX
 from privates.storages import private_media_storage
 from rest_framework.exceptions import ValidationError
 
@@ -126,6 +129,23 @@ class ExportSubmissionStatisticsView(
     # must be set by the ModelAdmin
     media: forms.Media | None = None
 
+    def form_valid(self, form: ExportStatisticsForm) -> HttpResponse:
+        start_date: date = form.cleaned_data["start_date"]
+        end_date: date = form.cleaned_data["end_date"]
+        dataset = form.export()
+        format = XLSX()
+        filename = f"submissions_{start_date.isoformat()}_{end_date.isoformat()}.xlsx"
+        return HttpResponse(
+            format.export_data(dataset),
+            content_type=format.get_content_type(),
+            headers={
+                "Content-Disposition": content_disposition_header(
+                    as_attachment=True,
+                    filename=filename,
+                ),
+            },
+        )
+
     def get_context_data(self, **kwargs):
         assert (
             self.media is not None

src/openforms/forms/forms/form_statistics.py

@@ -8,8 +8,10 @@
 from django.utils.translation import gettext_lazy as _
 
 from dateutil.relativedelta import relativedelta
+from tablib import Dataset
 
 from ..models import Form
+from ..statistics import export_registration_statistics
 
 
 def get_first_of_current_month() -> date:
@@ -50,3 +52,12 @@ class ExportStatisticsForm(forms.Form):
             "multiple options."
         ),
     )
+
+    def export(self) -> Dataset:
+        start_date: date = self.cleaned_data["start_date"]
+        end_date: date = self.cleaned_data["end_date"]
+        return export_registration_statistics(
+            start_date,
+            end_date,
+            self.cleaned_data["limit_to_forms"],
+        )

src/openforms/forms/statistics.py

@@ -0,0 +1,87 @@
+from datetime import date, datetime, time
+
+from django.contrib.contenttypes.models import ContentType
+from django.db import models
+from django.utils.timezone import make_aware
+from django.utils.translation import gettext_lazy as _
+
+from tablib import Dataset
+
+from openforms.logging import logevent
+from openforms.logging.models import TimelineLogProxy
+from openforms.submissions.models import Submission
+
+from .models import Form
+
+
+def export_registration_statistics(
+    start_date: date,
+    end_date: date,
+    limit_to_forms: models.QuerySet[Form] | None = None,
+) -> Dataset:
+    dataset = Dataset(
+        headers=(
+            _("Public reference"),
+            _("Form name (public)"),
+            _("Form name (internal)"),
+            _("Submitted on"),
+            _("Registered on"),
+        ),
+        title=_("Successfully registered submissions between {start} and {end}").format(
+            start=start_date.isoformat(),
+            end=end_date.isoformat(),
+        ),
+    )
+
+    _start_date = make_aware(datetime.combine(start_date, time.min))
+    _end_date = make_aware(datetime.combine(end_date, time.max))
+
+    log_records = TimelineLogProxy.objects.filter(
+        content_type=ContentType.objects.get_for_model(Submission),
+        timestamp__gte=_start_date,
+        timestamp__lt=_end_date,
+        # see openforms.logging.logevent for the data structure of the extra_data
+        # JSONField
+        extra_data__log_event=logevent.REGISTRATION_SUCCESS_EVENT,
+    ).order_by("timestamp")
+
+    if limit_to_forms:
+        form_ids = list(limit_to_forms.values_list("pk", flat=True))
+        log_records = log_records.filter(extra_data__form_id__in=form_ids)
+
+    for record in log_records.iterator():
+        extra_data = record.extra_data
+        # GFKs will be broken when the submissions are pruned, so prefer extracting
+        # information from the extra_data snapshot
+        submission: Submission | None = record.content_object
+        dataset.append(
+            (
+                # public reference
+                extra_data.get(
+                    "public_reference",
+                    (
+                        submission.public_registration_reference
+                        if submission
+                        else "-unknown-"
+                    ),
+                ),
+                # public form name
+                extra_data.get(
+                    "form_name", submission.form.name if submission else "-unknown-"
+                ),
+                # internal form name
+                extra_data.get(
+                    "internal_form_name",
+                    submission.form.internal_name if submission else "-unknown-",
+                ),
+                # when the user submitted the form
+                extra_data.get(
+                    "submitted_on",
+                    submission.completed_on.isoformat() if submission else None,
+                ),
+                # when the registration succeeeded - this must be close to when it was logged
+                record.timestamp.isoformat(),
+            )
+        )
+
+    return dataset

src/openforms/logging/logevent.py

@@ -216,10 +216,22 @@ def registration_start(submission: Submission):
 )
 
 
+REGISTRATION_SUCCESS_EVENT = "registration_success"
+
+
 def registration_success(submission: Submission, plugin):
+    extra_data = {
+        # note: these keys are used in form statistics exports!
+        "public_reference": submission.public_registration_reference,
+        "form_id": submission.form.pk,
+        "form_name": submission.form.name,
+        "internal_form_name": submission.form.internal_name,
+        "submitted_on": submission.completed_on,
+    }
     _create_log(
         submission,
-        "registration_success",
+        REGISTRATION_SUCCESS_EVENT,
+        extra_data=extra_data,
         plugin=plugin,
     )