Add support for limiting to certain session types

This is similar to limiting to by tracks.

Internally in the code it's not called "session", but "submission" type,
that naming is preserved throughout the code. The name "session" is used
for using facing parts like help messages.

Closes pretalx#26.

pretalx_public_voting/forms.py

@@ -111,6 +111,9 @@ class PublicVotingSettingsForm(I18nModelForm):
     def __init__(self, *args, **kwargs):
         super().__init__(*args, **kwargs)
         self.fields["limit_tracks"].queryset = self.instance.event.tracks.all()
+        self.fields[
+            "limit_submission_types"
+        ].queryset = self.instance.event.submission_types.all()
         minimum = self.instance.min_score
         maximum = self.instance.max_score
         for number in range(abs(maximum - minimum + 1)):
@@ -155,6 +158,7 @@ class Meta:
             "show_session_image",
             "show_session_description",
             "limit_tracks",
+            "limit_submission_types",
             "allowed_emails",
             "min_score",
             "max_score",
@@ -163,7 +167,9 @@ class Meta:
             "start": forms.DateTimeInput(attrs={"class": "datetimepickerfield"}),
             "end": forms.DateTimeInput(attrs={"class": "datetimepickerfield"}),
             "limit_tracks": forms.SelectMultiple(attrs={"class": "select2"}),
+            "limit_session_types": forms.SelectMultiple(attrs={"class": "select2"}),
         }
         field_classes = {
             "limit_tracks": SafeModelMultipleChoiceField,
+            "limit_submission_types": SafeModelMultipleChoiceField,
         }

pretalx_public_voting/migrations/0007_publicvotingsettings_limit_submission_types.py

@@ -0,0 +1,18 @@
+# Generated by Django 4.2.5 on 2023-09-30 17:09
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+    dependencies = [
+        ("submission", "0073_track_position"),
+        ("pretalx_public_voting", "0006_publicvotingsettings_limit_tracks"),
+    ]
+
+    operations = [
+        migrations.AddField(
+            model_name="publicvotingsettings",
+            name="limit_submission_types",
+            field=models.ManyToManyField(to="submission.submissiontype"),
+        ),
+    ]

pretalx_public_voting/models.py

@@ -78,6 +78,12 @@ class PublicVotingSettings(models.Model):
     limit_tracks = models.ManyToManyField(
         to="submission.Track", verbose_name=_("Limit to tracks"), blank=True
     )
+    limit_submission_types = models.ManyToManyField(
+        to="submission.SubmissionType",
+        verbose_name=_("Limit to session types"),
+        blank=True,
+        help_text=_("If no session type is selected, then all submission are shown."),
+    )
 
     @cached_property
     def allowed_email_list(self):

pretalx_public_voting/views.py

@@ -82,6 +82,11 @@ def get_queryset(self):
         tracks = self.request.event.public_vote_settings.limit_tracks.all()
         if tracks:
             base_qs = base_qs.filter(track__in=tracks)
+        submission_types = (
+            self.request.event.public_vote_settings.limit_submission_types.all()
+        )
+        if submission_types:
+            base_qs = base_qs.filter(submission_type__in=submission_types)
         submission_pks = list(base_qs.values_list("pk", flat=True))
         random.seed(self.hashed_email)
         random.shuffle(submission_pks)