Fixed #14370 -- Allowed using a Select2 widget for ForeignKey and ManyToManyField in the admin.

Thanks Florian Apolloner and Tim Graham for review and
contributing to the patch.

3 files changed, 134 insertions, 7 deletions

diff --git a/tests/modeladmin/models.py b/tests/modeladmin/models.py
index 861a2dbb9d..c0d3c772c9 100644
--- a/tests/modeladmin/models.py
+++ b/tests/modeladmin/models.py
@@ -14,6 +14,15 @@ class Band(models.Model):
         return self.name
 
 
+class Song(models.Model):
+    name = models.CharField(max_length=100)
+    band = models.ForeignKey(Band, models.CASCADE)
+    featuring = models.ManyToManyField(Band, related_name='featured')
+
+    def __str__(self):
+        return self.name
+
+
 class Concert(models.Model):
     main_band = models.ForeignKey(Band, models.CASCADE, related_name='main_concerts')
     opening_band = models.ForeignKey(Band, models.CASCADE, related_name='opening_concerts', blank=True)
diff --git a/tests/modeladmin/test_checks.py b/tests/modeladmin/test_checks.py
index acca6b18a2..eaca153bd8 100644
--- a/tests/modeladmin/test_checks.py
+++ b/tests/modeladmin/test_checks.py
@@ -6,14 +6,16 @@ from django.core.checks import Error
 from django.forms.models import BaseModelFormSet
 from django.test import SimpleTestCase
 
-from .models import Band, ValidationTestInlineModel, ValidationTestModel
+from .models import Band, Song, ValidationTestInlineModel, ValidationTestModel
 
 
 class CheckTestCase(SimpleTestCase):
 
-    def assertIsInvalid(self, model_admin, model, msg, id=None, hint=None, invalid_obj=None):
+    def assertIsInvalid(self, model_admin, model, msg, id=None, hint=None, invalid_obj=None, admin_site=None):
+        if admin_site is None:
+            admin_site = AdminSite()
         invalid_obj = invalid_obj or model_admin
-        admin_obj = model_admin(model, AdminSite())
+        admin_obj = model_admin(model, admin_site)
         self.assertEqual(admin_obj.check(), [Error(msg, hint=hint, obj=invalid_obj, id=id)])
 
     def assertIsInvalidRegexp(self, model_admin, model, msg, id=None, hint=None, invalid_obj=None):
@@ -30,8 +32,10 @@ class CheckTestCase(SimpleTestCase):
         self.assertEqual(error.id, id)
         self.assertRegex(error.msg, msg)
 
-    def assertIsValid(self, model_admin, model):
-        admin_obj = model_admin(model, AdminSite())
+    def assertIsValid(self, model_admin, model, admin_site=None):
+        if admin_site is None:
+            admin_site = AdminSite()
+        admin_obj = model_admin(model, admin_site)
         self.assertEqual(admin_obj.check(), [])
 
 
@@ -1153,3 +1157,89 @@ class ListDisplayEditableTests(CheckTestCase):
             "'list_display_links'.",
             id='admin.E123',
         )
+
+
+class AutocompleteFieldsTests(CheckTestCase):
+    def test_autocomplete_e036(self):
+        class Admin(ModelAdmin):
+            autocomplete_fields = 'name'
+
+        self.assertIsInvalid(
+            Admin, Band,
+            msg="The value of 'autocomplete_fields' must be a list or tuple.",
+            id='admin.E036',
+            invalid_obj=Admin,
+        )
+
+    def test_autocomplete_e037(self):
+        class Admin(ModelAdmin):
+            autocomplete_fields = ('nonexistent',)
+
+        self.assertIsInvalid(
+            Admin, ValidationTestModel,
+            msg=(
+                "The value of 'autocomplete_fields[0]' refers to 'nonexistent', "
+                "which is not an attribute of 'modeladmin.ValidationTestModel'."
+            ),
+            id='admin.E037',
+            invalid_obj=Admin,
+        )
+
+    def test_autocomplete_e38(self):
+        class Admin(ModelAdmin):
+            autocomplete_fields = ('name',)
+
+        self.assertIsInvalid(
+            Admin, ValidationTestModel,
+            msg=(
+                "The value of 'autocomplete_fields[0]' must be a foreign "
+                "key or a many-to-many field."
+            ),
+            id='admin.E038',
+            invalid_obj=Admin,
+        )
+
+    def test_autocomplete_e039(self):
+        class Admin(ModelAdmin):
+            autocomplete_fields = ('band',)
+
+        self.assertIsInvalid(
+            Admin, Song,
+            msg=(
+                'An admin for model "Band" has to be registered '
+                'to be referenced by Admin.autocomplete_fields.'
+            ),
+            id='admin.E039',
+            invalid_obj=Admin,
+        )
+
+    def test_autocomplete_e040(self):
+        class NoSearchFieldsAdmin(ModelAdmin):
+            pass
+
+        class AutocompleteAdmin(ModelAdmin):
+            autocomplete_fields = ('featuring',)
+
+        site = AdminSite()
+        site.register(Band, NoSearchFieldsAdmin)
+        self.assertIsInvalid(
+            AutocompleteAdmin, Song,
+            msg=(
+                'NoSearchFieldsAdmin must define "search_fields", because '
+                'it\'s referenced by AutocompleteAdmin.autocomplete_fields.'
+            ),
+            id='admin.E040',
+            invalid_obj=AutocompleteAdmin,
+            admin_site=site,
+        )
+
+    def test_autocomplete_is_valid(self):
+        class SearchFieldsAdmin(ModelAdmin):
+            search_fields = 'name'
+
+        class AutocompleteAdmin(ModelAdmin):
+            autocomplete_fields = ('featuring',)
+
+        site = AdminSite()
+        site.register(Band, SearchFieldsAdmin)
+        self.assertIsValid(AutocompleteAdmin, Song, admin_site=site)
diff --git a/tests/modeladmin/tests.py b/tests/modeladmin/tests.py
index 25b9dfed69..67bed3d697 100644
--- a/tests/modeladmin/tests.py
+++ b/tests/modeladmin/tests.py
@@ -7,14 +7,17 @@ from django.contrib.admin.options import (
     get_content_type_for_model,
 )
 from django.contrib.admin.sites import AdminSite
-from django.contrib.admin.widgets import AdminDateWidget, AdminRadioSelect
+from django.contrib.admin.widgets import (
+    AdminDateWidget, AdminRadioSelect, AutocompleteSelect,
+    AutocompleteSelectMultiple,
+)
 from django.contrib.auth.models import User
 from django.db import models
 from django.forms.widgets import Select
 from django.test import SimpleTestCase, TestCase
 from django.test.utils import isolate_apps
 
-from .models import Band, Concert
+from .models import Band, Concert, Song
 
 
 class MockRequest:
@@ -638,6 +641,31 @@ class ModelAdminTests(TestCase):
                     self.assertEqual(fetched.change_message, str(message))
                     self.assertEqual(fetched.object_repr, str(self.band))
 
+    def test_get_autocomplete_fields(self):
+        class NameAdmin(ModelAdmin):
+            search_fields = ['name']
+
+        class SongAdmin(ModelAdmin):
+            autocomplete_fields = ['featuring']
+            fields = ['featuring', 'band']
+
+        class OtherSongAdmin(SongAdmin):
+            def get_autocomplete_fields(self, request):
+                return ['band']
+
+        self.site.register(Band, NameAdmin)
+        try:
+            # Uses autocomplete_fields if not overridden.
+            model_admin = SongAdmin(Song, self.site)
+            form = model_admin.get_form(request)()
+            self.assertIsInstance(form.fields['featuring'].widget.widget, AutocompleteSelectMultiple)
+            # Uses overridden get_autocomplete_fields
+            model_admin = OtherSongAdmin(Song, self.site)
+            form = model_admin.get_form(request)()
+            self.assertIsInstance(form.fields['band'].widget.widget, AutocompleteSelect)
+        finally:
+            self.site.unregister(Band)
+
 
 class ModelAdminPermissionTests(SimpleTestCase):