Fix bug in pdnf_clause if empty data is passed (issue #92) (#93)

1. Fix issue #92 in pdnf_clause if empty data is passed
2. Removed outdated python 3.6 version from testing

.github/workflows/python-tests.yml

@@ -11,23 +11,11 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        python-version: ["3.6", "3.7", "3.8", "3.9", "3.10"]
+        python-version: ["3.7", "3.8", "3.9", "3.10"]
         postgres-version: ["9.4", "9.5", "9.6", "10", "11", "12", "13"]
         django-version: ["1.8", "1.9", "1.10", "1.11", "2.0", "2.1", "2.2", "3.0", "3.1", "3.2", "4.0"]
         exclude:
-        # Django 3.0+ doesn't support python 3.5
-        - python-version: "3.5"
-          django-version: "3.0"
-        - python-version: "3.5"
-          django-version: "3.1"
-        - python-version: "3.5"
-          django-version: "3.2"
-        - python-version: "3.5"
-          django-version: "4.0"
-
         # Django 4.0+ doesn't support python 3.6, 3.7
-        - python-version: "3.6"
-          django-version: "4.0"
         - python-version: "3.7"
           django-version: "4.0"
 
@@ -53,12 +41,6 @@ jobs:
 
         # python 3.6+ has deprecated issue with django before 1.11
         # https://stackoverflow.com/questions/41343263/provide-classcell-example-for-python-3-6-metaclass\
-        - python-version: "3.6"
-          django-version: "1.8"
-        - python-version: "3.6"
-          django-version: "1.9"
-        - python-version: "3.6"
-          django-version: "1.10"
         - python-version: "3.7"
           django-version: "1.8"
         - python-version: "3.7"

Dockerfile

@@ -33,10 +33,12 @@ WORKDIR /app/src
 # Install dependencies
 # set -eu "breaks" pipeline on first error
 COPY ./requirements-test.txt /app/requirements-test.txt
-RUN --mount=type=cache,target=/root/.cache/pip \
-  set -eu && \
+
+RUN set -eu && \
   apt-get update && \
-  apt-get install -y libpq-dev python3-dev && \
+  apt-get install -y libpq-dev python3-dev
+
+RUN --mount=type=cache,target=/root/.cache/pip \
   python3 -m pip install --upgrade pip setuptools wheel  && \
   python3 -m pip install --upgrade --requirement /app/requirements-test.txt
 

requirements-test.txt

@@ -1,7 +1,7 @@
 django>=1.7
 
 # FIXME On later versions I get strange error 'database connection isn't set to UTC'
-psycopg2-binary<=2.8.6
+psycopg2<=2.8.6
 
 pytz; python_version < '3.3'
 typing; python_version < '3.5'

runtests.py

@@ -9,12 +9,14 @@
 import sys
 
 import django
+import psycopg2
 from django.conf import settings
 from django.test.utils import get_runner
 
 if __name__ == "__main__":
     print('Django: ', django.VERSION)
     print('Python: ', sys.version)
+    print('Psycopg2: ', psycopg2.__version__)
 
     # Add the src directory to sys.path
     curdir = os.path.dirname(os.path.realpath(__file__))

setup.py

@@ -13,7 +13,7 @@
 
 setup(
     name='django-pg-bulk-update',
-    version='3.7.0',
+    version='3.7.1',
     packages=['django_pg_bulk_update'],
     package_dir={'': 'src'},
     url='https://github.com/M1hacka/django-pg-bulk-update',

src/django_pg_bulk_update/query.py

@@ -15,6 +15,7 @@
 from django.db.models.sql import UpdateQuery
 from django.db.models.sql.where import WhereNode
 
+from tests.compatibility import get_empty_q_object
 from .compatibility import get_postgres_version, get_model_fields, returning_available, string_types, Iterable
 from .set_functions import AbstractSetFunction, NowSetFunction
 from .types import TOperators, TFieldNames, TUpdateValues, TSetFunctions, TOperatorsValid, TUpdateValuesValid, \
@@ -305,8 +306,7 @@ def pdnf_clause(key_fields, field_values, key_fields_ops=()):
     field_values = list(field_values)
 
     if len(field_values) == 0:
-        # Empty condition should return empty result
-        return ~Q()
+        return get_empty_q_object()
 
     or_cond = Q()
     for values_item in field_values:

tests/compatibility.py

@@ -1,6 +1,9 @@
 from datetime import date
 
+from django.db.models import Value, Q, BooleanField
+from django.template.backends import django
 from django.utils.timezone import now
+from django.utils.tree import Node
 
 from django_pg_bulk_update.compatibility import get_postgres_version
 
@@ -16,3 +19,34 @@ def get_auto_now_date(key_is_unique=True):  # type: (bool) -> date
     :return: Date object
     """
     return date.today() if not key_is_unique or get_postgres_version() < (9, 5) else now().date()
+
+
+class EmptyQ(Q):
+    """
+    Empty condition should return empty result
+    See https://stackoverflow.com/questions/35893867/always-false-q-object
+    """
+    def __init__(self):
+        Node.__init__(self, children=[
+            ("pk", Value(False, output_field=BooleanField()))
+        ], connector=None, negated=False)
+
+    def __str__(self):
+        # Django before 3.0 raises 'TypeError: cannot unpack non-iterable Value object'
+        #   when trying to insert Q(Value(False, output_field=BooleanField())) to
+        return 'FALSE'
+
+
+def get_empty_q_object() -> Q:
+    """
+    Generates Q-Object, which leads to empty QuerySet.
+      See https://stackoverflow.com/questions/35893867/always-false-q-object
+    """
+    import django
+    if django.VERSION >= (3,):
+        return Q(Value(False, output_field=BooleanField()))
+
+    # Django before 3.0 doesn't work with not binary conditions and expects field name to be always present.
+    #   It raises TypeError: cannot unpack non-iterable Value object.
+    #   This condition raises EmptyResultSet while forming query and doesn't even execute it
+    return Q(pk__in=[])

tests/test_pdnf_clause.py

@@ -89,6 +89,9 @@ def test_lte(self):
     def test_between(self):
         self._test_filter({2, 3, 4}, ['id'], [[[2, 4]]], operations=['between'])
 
+    def test_empty_data(self):
+        self._test_filter(set(), ['id'], [])
+
 
 class TestReadmeExample(TestCase):
     def test_example(self):