docs: added sample application model for Django (#539)

* added sample application model * Update model.py * Update model.py * Update samples/python/django_sample/sample_app/model.py Co-authored-by: Knut Olav Løite <[email protected]> * Update model.py Co-authored-by: Knut Olav Løite <[email protected]>
GoogleCloudPlatform · Dec 16, 2022 · 72b173a · 72b173a
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diff --git a/samples/python/django/sample.py b/samples/python/django/sample.py
diff --git a/samples/python/django/setting.py b/samples/python/django/setting.py
diff --git a/samples/python/django_sample/sample_app/model.py b/samples/python/django_sample/sample_app/model.py
@@ -0,0 +1,85 @@
+''' Copyright 2022 Google LLC
+
+ Licensed under the Apache License, Version 2.0 (the "License");
+ you may not use this file except in compliance with the License.
+ You may obtain a copy of the License at
+
+      http://www.apache.org/licenses/LICENSE-2.0
+
+ Unless required by applicable law or agreed to in writing, software
+ distributed under the License is distributed on an "AS IS" BASIS,
+ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ See the License for the specific language governing permissions and
+ limitations under the License.
+'''
+
+from django.db import models
+from django.db.models import Q, F
+
+class BaseModel(models.Model):
+  class Meta():
+    abstract = True
+  created_at = models.DateTimeField()
+  updated_at = models.DateTimeField()
+
+class Singer(BaseModel):
+  class Meta():
+    db_table = 'singers'
+
+  id = models.CharField(primary_key=True, null=False)
+  first_name = models.CharField()
+  last_name = models.CharField(null=False)
+  full_name = models.CharField(null=False)
+  active = models.BooleanField()
+
+class Album(BaseModel):
+  class Meta():
+    db_table = 'albums'
+
+  id = models.CharField(primary_key=True, null=False)
+  title = models.CharField(null=False)
+  marketing_budget = models.DecimalField()
+  release_date = models.DateField()
+  cover_picture = models.BinaryField()
+  singer = models.ForeignKey(Singer, on_delete=models.DO_NOTHING)
+  created_at = models.DateTimeField()
+  updated_at = models.DateTimeField()
+
+
+class Track(BaseModel):
+  class Meta():
+    db_table = 'tracks'
+
+  # Here, id is a column that is supposed to be primary key by Django.
+  # But id column will just have a unique index in the actual table.
+  # In the actual table, (album_id, track_number) will be the primary key.
+  # This is done because Django doesn't support composite primary keys,
+  # but we need to have a composite primary key due to the fact that
+  # the "tracks" table is interleaved in "albums".
+
+  id = models.CharField(primary_key=True, null=False)
+  album = models.ForeignKey(Album, on_delete=models.DO_NOTHING)
+  track_number = models.BigIntegerField(null=False)
+  title = models.CharField(null=False)
+  sample_rate = models.FloatField()
+
+
+class Venue(BaseModel):
+  class Meta():
+    db_table = 'venues'
+  id = models.CharField(primary_key=True, null=False)
+  name = models.CharField(null=False)
+  description = models.CharField(null=False)
+
+
+class Concert(BaseModel):
+  class Meta():
+    db_table = 'concerts'
+    constraints = [models.CheckConstraint(check = Q(end_time__gte=F('start_time')), name='chk_end_time_after_start_time' )]
+  id = models.CharField(primary_key=True, null=False)
+  venue = models.ForeignKey(Venue, on_delete=models.DO_NOTHING)
+  singer = models.ForeignKey(Singer, on_delete=models.DO_NOTHING)
+  name = models.CharField(null=False)
+  start_time = models.DateTimeField(null=False)
+  end_time = models.DateTimeField(null=False)
+