Fix register_singular_query_field for non-page models

example/home/factories.py

@@ -11,6 +11,7 @@
     Advert,
     Author,
     Person,
+    SimpleModel,
 )
 from wagtail.core import blocks
 
@@ -138,3 +139,8 @@ class Meta:
 
     url = factory.Sequence(lambda n: f"Person {n}")
     text = fuzzy.FuzzyText()
+
+
+class SimpleModelFactory(factory.django.DjangoModelFactory):
+    class Meta:
+        model = SimpleModel

example/home/migrations/0019_simplemodel.py

@@ -0,0 +1,27 @@
+# Generated by Django 3.1.3 on 2020-12-08 18:50
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ("home", "0018_add_pagechooserblock"),
+    ]
+
+    operations = [
+        migrations.CreateModel(
+            name="SimpleModel",
+            fields=[
+                (
+                    "id",
+                    models.AutoField(
+                        auto_created=True,
+                        primary_key=True,
+                        serialize=False,
+                        verbose_name="ID",
+                    ),
+                ),
+            ],
+        ),
+    ]

example/home/models.py

@@ -40,6 +40,11 @@
 from home.blocks import StreamFieldBlock
 
 
+@register_singular_query_field("simpleModel")
+class SimpleModel(models.Model):
+    pass
+
+
 class HomePage(Page):
     pass
 

example/home/test/test_general.py

@@ -0,0 +1,54 @@
+from example.tests.test_grapple import BaseGrappleTest
+
+from home.factories import BlogPageFactory, SimpleModelFactory
+
+
+class TestRegisterSingularQueryField(BaseGrappleTest):
+    def test_singular_blog_page_query(self):
+        def query():
+            return """
+        {
+            firstPost {
+                id
+            }
+        }
+        """
+
+        blog_post = BlogPageFactory()
+        another_post = BlogPageFactory()
+        results = self.client.execute(query())
+
+        self.assertTrue("firstPost" in results["data"])
+        self.assertEqual(int(results["data"]["firstPost"]["id"]), blog_post.id)
+
+        results = self.client.execute(
+            """
+            {
+                firstPost(order: "-id") {
+                    id
+                }
+            }
+            """
+        )
+
+        self.assertTrue("firstPost" in results["data"])
+        self.assertEqual(int(results["data"]["firstPost"]["id"]), another_post.id)
+
+    def test_singular_django_model_query(self):
+        def query():
+            return """
+        {
+            simpleModel {
+                id
+            }
+        }
+        """
+
+        results = self.client.execute(query())
+        self.assertTrue("simpleModel" in results["data"])
+        self.assertIsNone(results["data"]["simpleModel"])
+
+        instance = SimpleModelFactory()
+        results = self.client.execute(query())
+
+        self.assertEqual(int(results["data"]["simpleModel"]["id"]), instance.id)

grapple/helpers.py

@@ -263,7 +263,7 @@ def resolve_singular(self, _, info, **kwargs):
 
                         return qs.live().public().filter(**kwargs).first()
 
-                    return cls.filter(**kwargs).first()
+                    return qs.filter(**kwargs).first()
                 except:
                     return None