From 8a7aac7f45e13e9d0207142091661826892e944f Mon Sep 17 00:00:00 2001
From: Filip Stenbacka <filip.stenbacka@gmail.com>
Date: Wed, 30 Aug 2023 21:53:19 +0300
Subject: [PATCH] Added an extended CharFilter that can filter null/~null if
 given certain keywords. This resolves issue #178.

---
 teknologr/api/filters.py      | 30 ++++++++++++++++++++------
 teknologr/api/tests_filter.py | 40 +++++++++++++++++++++++++++++++++++
 2 files changed, 64 insertions(+), 6 deletions(-)

diff --git a/teknologr/api/filters.py b/teknologr/api/filters.py
index d6f1ccd1..bed9b6fa 100644
--- a/teknologr/api/filters.py
+++ b/teknologr/api/filters.py
@@ -6,12 +6,30 @@
 
 class BooleanFilter(django_filters.BooleanFilter):
     '''
-    The defualt null label is for some reason 'unknown', but I want it to be ''
+    The default null label is for some reason 'unknown', but I want it to be ''
     '''
     def __init__(self, *args, **kwargs):
         kwargs['widget'] = django_filters.widgets.BooleanWidget
         super().__init__(*args, **kwargs)
 
+class CharFilterWithKeywords(django_filters.CharFilter):
+    '''
+    Take a CharFilter. You can filter on a specific phrase or leave it empty, but what if you want to filter null/empty values? This filter applies predetermined null/~null filters if the value is a certain keyword:
+        - '-' => isnull=True
+        - '*' => isnull=False
+
+    Not suitable for fields where the keywords are possible values, and does not apply if the 'method' argument is given in the constructor.
+    '''
+
+    def filter(self, qs, value):
+        q = Q(**{f'{self.field_name}__isnull': True}) | Q(**{f'{self.field_name}__exact': ''})
+        if value == '-':
+            return qs.filter(q)
+        if value == '*':
+            return qs.exclude(q)
+        return super().filter(qs, value)
+
+
 class BaseFilter(django_filters.rest_framework.FilterSet):
     '''
     Base filter class that takes care of normal users from using staff-only filters.
@@ -92,11 +110,11 @@ class MemberFilter(BaseFilter):
         method='filter_address',
         label='Adressen innehåller',
     )
-    email = django_filters.CharFilter(
+    email = CharFilterWithKeywords(
         lookup_expr='icontains',
         label='E-postadressen innehåller',
     )
-    degree_programme = django_filters.CharFilter(
+    degree_programme = CharFilterWithKeywords(
         lookup_expr='icontains',
         label='Studieprogrammet innehåller',
     )
@@ -116,7 +134,7 @@ class MemberFilter(BaseFilter):
     birth_date = django_filters.DateFromToRangeFilter(
         label='Född mellan',
     )
-    student_id = django_filters.CharFilter(
+    student_id = CharFilterWithKeywords(
         label='Studienummer',
     )
     dead = BooleanFilter(
@@ -135,10 +153,10 @@ class MemberFilter(BaseFilter):
         lookup_expr='icontains',
         label='Kommentaren innehåller',
     )
-    username = django_filters.CharFilter(
+    username = CharFilterWithKeywords(
         label='Användarnamn',
     )
-    bill_code = django_filters.CharFilter(
+    bill_code = CharFilterWithKeywords(
         label='BILL-konto',
     )
 
diff --git a/teknologr/api/tests_filter.py b/teknologr/api/tests_filter.py
index 77feab7e..f04f01ea 100644
--- a/teknologr/api/tests_filter.py
+++ b/teknologr/api/tests_filter.py
@@ -810,6 +810,46 @@ def setUp(self):
             dead=False,
         )
 
+class MemberFilterUsernameNullTest(BaseAPITest, TestCases):
+    def setUp(self):
+        super().setUp()
+
+        self.query = 'username=-'
+        self.n_normal = 3 # Filter does not work for normal users
+        self.n_staff = 2
+
+        # Should only be found by staff
+        Member.objects.create(
+            given_names='Test',
+            surname='von Test',
+            username='',
+        )
+        Member.objects.create(
+            given_names='Test',
+            surname='von Test',
+            username=None,
+        )
+
+class MemberFilterUsernameAnyTest(BaseAPITest, TestCases):
+    def setUp(self):
+        super().setUp()
+
+        self.query = 'username=*'
+        self.n_normal = 3 # Filter does not work for normal users
+        self.n_staff = 1
+
+        # Should not be found by staff
+        Member.objects.create(
+            given_names='Test',
+            surname='von Test',
+            username='',
+        )
+        Member.objects.create(
+            given_names='Test',
+            surname='von Test',
+            username=None,
+        )
+
 
 class MemberFilterBillCodeTest(BaseAPITest, TestCases):
     def setUp(self):