Won Django Associations Solution

amazon/store/models.py

@@ -1,13 +1,22 @@
 from django.db import models
 
+
 class User(models.Model):
     pass
 
+
 class Shop(models.Model):
-    pass
+    owner = models.OneToOneField(
+        'User', on_delete=models.CASCADE, related_name='shop')
+
 
 class Product(models.Model):
-    pass
+    shop = models.ForeignKey(
+        'Shop', on_delete=models.CASCADE, related_name='products')
+
 
 class Review(models.Model):
-    pass
+    product = models.ForeignKey(
+        'Product', on_delete=models.CASCADE, related_name='reviews')
+    user = models.ForeignKey(
+        'User', on_delete=models.CASCADE, related_name='reviews')

grubhub/foodDelivery/models.py

@@ -1,16 +1,32 @@
 from django.db import models
 
+
 class User(models.Model):
     pass
 
+
 class Restaurant(models.Model):
     pass
 
+
 class Order(models.Model):
-    pass
+    user = models.ForeignKey(
+        'User', on_delete=models.CASCADE, related_name='orders')
+    restaurant = models.ForeignKey(
+        'Restaurant', on_delete=models.CASCADE, related_name='orders')
+
 
 class FoodItem(models.Model):
-    pass
+    orders = models.ManyToManyField(
+        'Order', related_name='food_items', through='OrderFoodItem')
+
+
+# orders and food_items have a many-to-many relationship
+# we define order_food_items to be the intermediate table
+
 
 class OrderFoodItem(models.Model):
-    pass
+    order = models.ForeignKey(
+        'Order', on_delete=models.CASCADE, related_name='order_food_items')
+    food_item = models.ForeignKey(
+        'FoodItem', on_delete=models.CASCADE, related_name='order_food_items')

imdb/moviedb/migrations/0001_initial.py

@@ -0,0 +1,40 @@
+# Generated by Django 2.1.5 on 2021-06-25 14:11
+
+from django.db import migrations, models
+import django.db.models.deletion
+
+
+class Migration(migrations.Migration):
+
+    initial = True
+
+    dependencies = [
+    ]
+
+    operations = [
+        migrations.CreateModel(
+            name='Actor',
+            fields=[
+                ('id', models.AutoField(auto_created=True, primary_key=True, serialize=False, verbose_name='ID')),
+            ],
+        ),
+        migrations.CreateModel(
+            name='Movie',
+            fields=[
+                ('id', models.AutoField(auto_created=True, primary_key=True, serialize=False, verbose_name='ID')),
+            ],
+        ),
+        migrations.CreateModel(
+            name='Role',
+            fields=[
+                ('id', models.AutoField(auto_created=True, primary_key=True, serialize=False, verbose_name='ID')),
+                ('actor', models.ForeignKey(on_delete=django.db.models.deletion.CASCADE, related_name='roles', to='moviedb.Actor')),
+                ('movie', models.ForeignKey(on_delete=django.db.models.deletion.CASCADE, related_name='roles', to='moviedb.Movie')),
+            ],
+        ),
+        migrations.AddField(
+            model_name='movie',
+            name='actors',
+            field=models.ManyToManyField(related_name='movies', through='moviedb.Role', to='moviedb.Actor'),
+        ),
+    ]

imdb/moviedb/models.py

@@ -1,9 +1,17 @@
 from django.db import models
+from django.db.models.deletion import CASCADE
+
 
 class Actor(models.Model):
     pass
 
+
 class Movie(models.Model):
-    pass
+    actors = models.ManyToManyField(
+        Actor, through='Role', related_name='movies')
+    # through specifies what the intermediate table is
+
+
 class Role(models.Model):
-    pass
+    actor = models.ForeignKey(Actor, on_delete=CASCADE, related_name='roles')
+    movie = models.ForeignKey(Movie, on_delete=CASCADE, related_name='roles')

medium/blog/migrations/0005_auto_20210625_1454.py

@@ -0,0 +1,19 @@
+# Generated by Django 2.1.5 on 2021-06-25 14:54
+
+from django.db import migrations, models
+import django.db.models.deletion
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('blog', '0004_auto_20210625_1452'),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name='comment',
+            name='post',
+            field=models.ForeignKey(on_delete=django.db.models.deletion.CASCADE, related_name='comments', to='blog.Post'),
+        ),
+    ]

medium/blog/models.py

@@ -1,12 +1,23 @@
 from django.db import models
 
 # Create your models here.
+
+
 class User(models.Model):
     pass
 
+
 class Post(models.Model):
-    pass
+    # a post has one author. link a foreignkey to author
+    author = models.ForeignKey(
+        'User', on_delete=models.CASCADE, related_name='posts')
+
 
 class Comment(models.Model):
-    pass
-
+    # a comment only belongs to one post. link a foreignkey to post
+    post = models.ForeignKey(
+        'Post', on_delete=models.CASCADE, related_name='comments')
+
+    # a comment has one author. link a foreignkey to author
+    author = models.ForeignKey(
+        'User', on_delete=models.CASCADE, related_name='comments')