[FR] Add Feature flags (#4982)

* make currency choices independend

* Remove check for field, just try to get rid of it

* Add IF EXISTS to avoid error (works in postgres)

* Look for operational error, not programming error

* Use variants, depending on errors caused

* [FR] Add Feature flags
Fixes #4965

* Add option to define custom flags

* Revert "make currency choices independend"

This reverts commit ab84a7ff83.

* try fixing mysql

* more safeguards

* fix executioner call

* a fck

* use migrations. syntax

* and another round for mysql

* revert print change

* use UTC for datetime

* Update part.migrations.0112

- Add custom migration class which handles errors

* Add unit test for migration

- Ensure that the new fields are added to the model

* Update reference to PR

* fix ruleset for missing_models

* fix ruleset for flags_flagstate

* add API endpoints for flags

* add tests for new API endpoints

* fix tests

* fix merge

* fix tests

---------

Co-authored-by: martin <martin@iggland.com>
Co-authored-by: Oliver Walters <oliver.henry.walters@gmail.com>

InvenTree/common/api.py

@@ -2,6 +2,7 @@
 
 import json
 
+from django.conf import settings
 from django.http.response import HttpResponse
 from django.urls import include, path, re_path
 from django.utils.decorators import method_decorator
@@ -480,6 +481,29 @@ class ProjectCodeDetail(RetrieveUpdateDestroyAPI):
     permission_classes = [permissions.IsAuthenticated, IsStaffOrReadOnly]
 
 
+class FlagList(ListAPI):
+    """List view for feature flags."""
+
+    queryset = settings.FLAGS
+    serializer_class = common.serializers.FlagSerializer
+    permission_classes = [permissions.AllowAny, ]
+
+
+class FlagDetail(RetrieveAPI):
+    """Detail view for an individual feature flag."""
+
+    serializer_class = common.serializers.FlagSerializer
+    permission_classes = [permissions.AllowAny, ]
+
+    def get_object(self):
+        """Attempt to find a config object with the provided key."""
+        key = self.kwargs['key']
+        value = settings.FLAGS.get(key, None)
+        if not value:
+            raise NotFound()
+        return {key: value}
+
+
 settings_api_urls = [
     # User settings
     re_path(r'^user/', include([
@@ -552,6 +576,11 @@ common_api_urls = [
         re_path(r'^.*$', NewsFeedEntryList.as_view(), name='api-news-list'),
     ])),
 
+    # Flags
+    path('flags/', include([
+        path('<str:key>/', FlagDetail.as_view(), name='api-flag-detail'),
+        re_path(r'^.*$', FlagList.as_view(), name='api-flag-list'),
+    ])),
 ]
 
 admin_api_urls = [

InvenTree/common/serializers.py

@@ -1,7 +1,9 @@
 """JSON serializers for common components."""
 
+
 from django.urls import reverse
 
+from flags.state import flag_state
 from rest_framework import serializers
 
 from common.models import (InvenTreeSetting, InvenTreeUserSetting,
@@ -269,3 +271,19 @@ class ProjectCodeSerializer(InvenTreeModelSerializer):
             'code',
             'description'
         ]
+
+
+class FlagSerializer(serializers.Serializer):
+    """Serializer for feature flags."""
+
+    def to_representation(self, instance):
+        """Return the configuration data as a dictionary."""
+        request = self.context.get('request')
+        if not isinstance(instance, str):
+            instance = list(instance.keys())[0]
+        data = {'key': instance, 'state': flag_state(instance, request=request)}
+
+        if request and request.user.is_superuser:
+            data['conditions'] = self.instance[instance]
+
+        return data

InvenTree/common/tests.py

@@ -875,6 +875,43 @@ class CommonTest(InvenTreeAPITestCase):
         self.user.is_superuser = False
         self.user.save()
 
+    def test_flag_api(self):
+        """Test flag URLs."""
+        # Not superuser
+        response = self.get(reverse('api-flag-list'), expected_code=200)
+        self.assertEqual(len(response.data), 2)
+        self.assertEqual(response.data[0]['key'], 'EXPERIMENTAL')
+
+        # Turn into superuser
+        self.user.is_superuser = True
+        self.user.save()
+
+        # Successful checks
+        response = self.get(reverse('api-flag-list'), expected_code=200)
+        self.assertEqual(len(response.data), 2)
+        self.assertEqual(response.data[0]['key'], 'EXPERIMENTAL')
+        self.assertTrue(response.data[0]['conditions'])
+
+        response = self.get(reverse('api-flag-detail', kwargs={'key': 'EXPERIMENTAL'}), expected_code=200)
+        self.assertEqual(len(response.data), 3)
+        self.assertEqual(response.data['key'], 'EXPERIMENTAL')
+        self.assertTrue(response.data['conditions'])
+
+        # Try without param -> false
+        response = self.get(reverse('api-flag-detail', kwargs={'key': 'NEXT_GEN'}), expected_code=200)
+        self.assertFalse(response.data['state'])
+
+        # Try with param -> true
+        response = self.get(reverse('api-flag-detail', kwargs={'key': 'NEXT_GEN'}), {'ngen': ''}, expected_code=200)
+        self.assertTrue(response.data['state'])
+
+        # Try non existent flag
+        response = self.get(reverse('api-flag-detail', kwargs={'key': 'NON_EXISTENT'}), expected_code=404)
+
+        # Turn into normal user again
+        self.user.is_superuser = False
+        self.user.save()
+
 
 class ColorThemeTest(TestCase):
     """Tests for ColorTheme."""