Iteration over f_expressions example

Author: TanyaAng

styleguide_example/blog_examples/f_expressions/service.py renamed to styleguide_example/blog_examples/f_expressions/db_functions.py

@@ -0,0 +1,16 @@
+from django.db import models
+
+"""
+This is a basic model used to illustrate 
+JSON field increment with f expressions
+"""
+
+
+class SomeDataModel(models.Model):
+    name = models.CharField(
+        max_length=255,
+        blank=True,
+    )
+    stored_field = models.JSONField(
+        blank=True,
+    )

styleguide_example/blog_examples/f_expressions/models.py

@@ -0,0 +1,55 @@
+from django.test import TestCase
+
+from styleguide_example.blog_examples.f_expressions.db_functions import JSONIncrement
+from styleguide_example.blog_examples.models import SomeDataModel
+
+
+class JSONIncrementTests(TestCase):
+    def setUp(self) -> None:
+        self.first_entity_stored_field = {"first_key": 1, "second_key": 2, "third_key": 3}
+        self.second_entity_stored_field = {"first_key": 4, "second_key": 5, "third_key": 6}
+        self.increment_value = 10
+
+    def test_json_increment_in_model(self):
+        SomeDataModel.objects.bulk_create(
+            [
+                SomeDataModel(name="First name", stored_field=self.first_entity_stored_field),
+                SomeDataModel(name="Second name", stored_field=self.second_entity_stored_field),
+            ]
+        )
+
+        first_entity = SomeDataModel.objects.first()
+        second_entity = SomeDataModel.objects.last()
+
+        expected_first_entity_stored_field = self.first_entity_stored_field
+        actual_first_entity_stored_field = first_entity.stored_field
+
+        expected_second_entity_stored_field = self.second_entity_stored_field
+        actual_second_entity_stored_field = second_entity.stored_field
+
+        self.assertEqual(expected_first_entity_stored_field, actual_first_entity_stored_field)
+        self.assertEqual(expected_second_entity_stored_field, actual_second_entity_stored_field)
+
+        SomeDataModel.objects.filter(name="First name").update(
+            stored_field=JSONIncrement("stored_field__first_key", self.increment_value)
+        )
+
+        first_entity = SomeDataModel.objects.first()
+        second_entity = SomeDataModel.objects.last()
+
+        """
+        Expect only first_entity JSON field with name first_key to be incremented
+        """
+
+        expected_first_entity_stored_field = {
+            "first_key": self.first_entity_stored_field["first_key"] + self.increment_value,
+            "second_key": self.first_entity_stored_field["second_key"],
+            "third_key": self.first_entity_stored_field["third_key"],
+        }
+        actual_first_entity_stored_field = first_entity.stored_field
+
+        expected_second_entity_stored_field = self.second_entity_stored_field
+        actual_second_entity_stored_field = second_entity.stored_field
+
+        self.assertEqual(expected_first_entity_stored_field, actual_first_entity_stored_field)
+        self.assertEqual(expected_second_entity_stored_field, actual_second_entity_stored_field)

styleguide_example/blog_examples/tests/services/__init__.py renamed to styleguide_example/blog_examples/f_expressions/tests/__init__.py

@@ -1,4 +1,4 @@
-# Generated by Django 4.1.6 on 2023-05-09 11:10
+# Generated by Django 4.1.6 on 2023-05-10 06:34
 
 from django.db import migrations, models
 

styleguide_example/blog_examples/f_expressions/tests/test_f_expressions.py

@@ -1,6 +1,8 @@
 from django.db import models
 from django.utils import timezone
 
+from .f_expressions.models import SomeDataModel
+
 
 class TimestampsWithAuto(models.Model):
     created_at = models.DateTimeField(auto_now_add=True)
@@ -29,13 +31,3 @@ class TimestampsOpinionated(models.Model):
 
     created_at = models.DateTimeField(default=timezone.now)
     updated_at = models.DateTimeField(blank=True, null=True)
-
-
-class SomeDataModel(models.Model):
-    name = models.CharField(
-        max_length=255,
-        blank=True,
-    )
-    stored_field = models.JSONField(
-        blank=True,
-    )