From b363d1117c0526d866183cdfc41837de9e3306c5 Mon Sep 17 00:00:00 2001
From: Eliot Berriot <contact@eliotberriot.com>
Date: Thu, 29 Aug 2019 12:20:30 +0200
Subject: [PATCH] Added GenericRelationFilter

---
 api/funkwhale_api/common/fields.py | 58 ++++++++++++++++++++++++++++++
 api/tests/common/test_fields.py    | 36 +++++++++++++++++++
 2 files changed, 94 insertions(+)

diff --git a/api/funkwhale_api/common/fields.py b/api/funkwhale_api/common/fields.py
index f1a3e77bd..f206b626e 100644
--- a/api/funkwhale_api/common/fields.py
+++ b/api/funkwhale_api/common/fields.py
@@ -57,6 +57,64 @@ class SmartSearchFilter(django_filters.CharFilter):
         return search.apply(qs, cleaned)
 
 
+def get_generic_filter_query(value, relation_name, choices):
+    parts = value.split(":", 1)
+    type = parts[0]
+    try:
+        conf = choices[type]
+    except KeyError:
+        raise forms.ValidationError("Invalid type")
+    related_queryset = conf["queryset"]
+    related_model = related_queryset.model
+    filter_query = models.Q(
+        **{
+            "{}_content_type__app_label".format(
+                relation_name
+            ): related_model._meta.app_label,
+            "{}_content_type__model".format(
+                relation_name
+            ): related_model._meta.model_name,
+        }
+    )
+    if len(parts) > 1:
+        id_attr = conf.get("id_attr", "id")
+        id_field = conf.get("id_field", serializers.IntegerField(min_value=1))
+        try:
+            id_value = parts[1]
+            id_value = id_field.to_internal_value(id_value)
+        except (TypeError, KeyError, serializers.ValidationError):
+            raise forms.ValidationError("Invalid id")
+        query_getter = conf.get(
+            "get_query", lambda attr, value: models.Q(**{attr: value})
+        )
+        obj_query = query_getter(id_attr, id_value)
+        try:
+            obj = related_queryset.get(obj_query)
+        except related_queryset.model.DoesNotExist:
+            raise forms.ValidationError("Invalid object")
+        filter_query &= models.Q(**{"{}_id".format(relation_name): obj.id})
+
+    return filter_query
+
+
+class GenericRelationFilter(django_filters.CharFilter):
+    def __init__(self, relation_name, choices, *args, **kwargs):
+        self.relation_name = relation_name
+        self.choices = choices
+        super().__init__(*args, **kwargs)
+
+    def filter(self, qs, value):
+        if not value:
+            return qs
+        try:
+            filter_query = get_generic_filter_query(
+                value, relation_name=self.relation_name, choices=self.choices
+            )
+        except forms.ValidationError:
+            return qs.none()
+        return qs.filter(filter_query)
+
+
 class GenericRelation(serializers.JSONField):
     def __init__(self, choices, *args, **kwargs):
         self.choices = choices
diff --git a/api/tests/common/test_fields.py b/api/tests/common/test_fields.py
index 21e85b700..2cc07f1b2 100644
--- a/api/tests/common/test_fields.py
+++ b/api/tests/common/test_fields.py
@@ -67,3 +67,39 @@ def test_generic_relation_field_validation_error(payload, expected_error, factor
 
     with pytest.raises(fields.serializers.ValidationError, match=expected_error):
         f.to_internal_value(payload)
+
+
+def test_generic_relation_filter_target_type(factories):
+    user = factories["users.User"]()
+    note = factories["moderation.Note"](target=user)
+    factories["moderation.Note"](target=factories["music.Artist"]())
+    f = fields.GenericRelationFilter(
+        "target",
+        {
+            "user": {
+                "queryset": user.__class__.objects.all(),
+                "id_attr": "username",
+                "id_field": fields.serializers.CharField(),
+            }
+        },
+    )
+    qs = f.filter(note.__class__.objects.all(), "user")
+    assert list(qs) == [note]
+
+
+def test_generic_relation_filter_target_type_and_id(factories):
+    user = factories["users.User"]()
+    note = factories["moderation.Note"](target=user)
+    factories["moderation.Note"](target=factories["users.User"]())
+    f = fields.GenericRelationFilter(
+        "target",
+        {
+            "user": {
+                "queryset": user.__class__.objects.all(),
+                "id_attr": "username",
+                "id_field": fields.serializers.CharField(),
+            }
+        },
+    )
+    qs = f.filter(note.__class__.objects.all(), "user:{}".format(user.username))
+    assert list(qs) == [note]