Add: queryset api tutorial code

Author: lordmyshepherd

README.md

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+# queryset-api

__pycache__/decorators.cpython-38.pyc

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+from django.contrib import admin
+
+# Register your models here.

__pycache__/decorators.cpython-39.pyc

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+from django.apps import AppConfig
+
+
+class BooksConfig(AppConfig):
+    name = 'books'

books/__init__.py

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+import random
+
+from django.core.management.base import BaseCommand
+from ...models import Publisher, Store, Book
+
+
+class Command(BaseCommand):
+    """
+    이 커맨드는 5개의 Publisher, 100개의 books와 10개의 Stores를 DB에 insert합니다.
+    """
+
+    def handle(self, *args, **options):
+        Publisher.objects.all().delete()
+        Book.objects.all().delete()
+        Store.objects.all().delete()
+
+        # create 5 publishers
+        publishers = [Publisher(name=f"Publisher{index}") for index in range(1, 20)]
+        Publisher.objects.bulk_create(publishers)
+
+        # create 20 books for every publishers
+        counter = 0
+        books = []
+        for publisher in Publisher.objects.all():
+            for i in range(1000):
+                counter = counter + 1
+                books.append(Book(name=f"Book{counter}", price=random.randint(50, 300), publisher=publisher))
+
+        Book.objects.bulk_create(books)
+
+        # create 10 stores and insert 10 books in every store
+        books = list(Book.objects.all())
+        for i in range(1000):
+            temp_books = [books.pop(0) for i in range(10)]
+            store = Store.objects.create(name=f"Store{i+1}")
+            store.books.set(temp_books)
+            store.save()

books/__pycache__/__init__.cpython-37.pyc

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+# Generated by Django 3.1.2 on 2020-11-25 02:06
+
+from django.db import migrations, models
+import django.db.models.deletion
+
+
+class Migration(migrations.Migration):
+
+    initial = True
+
+    dependencies = [
+    ]
+
+    operations = [
+        migrations.CreateModel(
+            name='Book',
+            fields=[
+                ('id', models.AutoField(auto_created=True, primary_key=True, serialize=False, verbose_name='ID')),
+                ('name', models.CharField(max_length=255)),
+                ('price', models.IntegerField(default=0)),
+            ],
+        ),
+        migrations.CreateModel(
+            name='Publisher',
+            fields=[
+                ('id', models.AutoField(auto_created=True, primary_key=True, serialize=False, verbose_name='ID')),
+                ('name', models.CharField(max_length=255)),
+            ],
+        ),
+        migrations.CreateModel(
+            name='Store',
+            fields=[
+                ('id', models.AutoField(auto_created=True, primary_key=True, serialize=False, verbose_name='ID')),
+                ('name', models.CharField(max_length=255)),
+                ('books', models.ManyToManyField(to='books.Book')),
+            ],
+        ),
+        migrations.AddField(
+            model_name='book',
+            name='publisher',
+            field=models.ForeignKey(on_delete=django.db.models.deletion.CASCADE, to='books.publisher'),
+        ),
+    ]

books/__pycache__/__init__.cpython-38.pyc

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+# Generated by Django 3.1.2 on 2020-11-25 05:12
+
+from django.db import migrations
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('books', '0001_initial'),
+    ]
+
+    operations = [
+        migrations.AlterModelTable(
+            name='book',
+            table='books',
+        ),
+        migrations.AlterModelTable(
+            name='publisher',
+            table='publishers',
+        ),
+        migrations.AlterModelTable(
+            name='store',
+            table='stores',
+        ),
+    ]

books/__pycache__/__init__.cpython-39.pyc

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+from django.db import models
+
+class Publisher(models.Model):
+    name = models.CharField(max_length=255)
+    
+    class Meta:
+        db_table = 'publishers'
+
+    def __str__(self):
+        return self.name
+
+
+class Book(models.Model):
+    name = models.CharField(max_length=255)
+    price = models.IntegerField(default=0)
+    publisher = models.ForeignKey(Publisher, on_delete=models.CASCADE)
+    
+    class Meta:
+        db_table = 'books'
+
+    def __str__(self):
+        return self.name
+
+
+class Store(models.Model):
+    name = models.CharField(max_length=255)
+    books = models.ManyToManyField(Book)
+
+    class Meta:
+        db_table = 'stores'
+
+    def __str__(self):
+        return self.name

books/__pycache__/models.cpython-37.pyc

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+from django.test import TestCase
+
+# Create your tests here.

books/__pycache__/models.cpython-38.pyc

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+from django.views import View
+from .models      import Book, Store
+from django.http  import JsonResponse
+from decorators   import query_debugger
+from django.db.models    import Prefetch
+
+class BooksWithAllMethodView(View):
+    @query_debugger
+    def get(self, request):
+        print('Book에서 Publisher Instance에 접근하는 경우 <정참조>')
+        queryset = Book.objects.all()
+        books = []
+        for book in queryset: 
+            books.append({
+                'id': book.id,
+                'name': book.name,
+                'publisher': book.publisher.name # book.publisher에 접근, 캐싱되지 않은 데이터이므로 query 발생
+                }
+            )
+        return JsonResponse({'books_with_all_method' : books }, status=200)
+
+class BooksWithSelectRelatedView(View):
+    @query_debugger
+    def get(self, request):
+        print('Book에서 Publisher Instance에 접근하는 경우 <정참조>')
+        queryset = Book.objects.select_related("publisher").all()
+        books = []
+        for book in queryset: 
+            books.append({
+                'id': book.id,
+                'name': book.name,
+                'publisher': book.publisher.name
+                }
+            )
+        return JsonResponse({'books_with_all_method' : books }, status=200)
+
+
+# Store(1) : Book(M)
+# Store에서 Book Instance에 접근하는 경우 <역참조>
+class StoresWithAllMethodView(View):
+    @query_debugger
+    def get(self, request):
+        print(f'Store에서 Book Instance에 접근하는 경우 <역참조>')
+        queryset = Store.objects.all()
+        stores = []
+        for store in queryset: 
+            books = [book.name for book in store.books.all()] 
+            stores.append({
+                'id': store.id,
+                'name': store.name,
+                'books': books
+                }
+            )
+        return JsonResponse({'stores_with_all_method' : stores }, status=200)
+
+class StoresWithPrefetchRelatedView(View):
+    @query_debugger
+    def get(self, request):
+        print(f'Store에서 Book Instance에 접근하는 경우 <역참조>')
+        queryset = Store.objects.prefetch_related("books").all()
+        stores = []
+        for store in queryset:
+            books = [book.name for book in store.books.all()]
+            stores.append({'id': store.id, 'name': store.name, 'books': books})
+
+        return JsonResponse({'stores_with_prefetch_related' : stores }, status=200)
+
+
+class StoresWithPrefetchNoneObjectView(View):
+    @query_debugger
+    def get(self, request):
+        print(f'Store에서 Book Instance에 접근하는 경우 <역참조>')
+        queryset = Store.objects.prefetch_related("books").all()
+        stores = []
+        for store in queryset:
+            books = [book.name for book in store.books.filter(name='Book1')]
+            stores.append({'id': store.id, 'name': store.name, 'books': books})
+
+        return JsonResponse({'stores_with_prefetch_related' : stores }, status=200)
+
+class StoresWithPrefetchObjectView(View):
+    @query_debugger
+    def get(self, request):
+        print(f'Store에서 Book Instance에 접근하는 경우 <역참조>')
+        queryset = Store.objects.prefetch_related(Prefetch('books', queryset=Book.objects.filter(name='Book1')))
+        stores = []
+        for store in queryset:
+            books = [book.name for book in store.books.all()]
+            stores.append({'id': store.id, 'name': store.name, 'books': books})
+
+        return JsonResponse({'stores_with_prefetch_related' : stores }, status=200)
+
+
+class StoresWithPrefetchObjectView(View):
+    @query_debugger
+    def get(self, request):
+        print(f'Store에서 Book Instance에 접근하는 경우 <역참조>')
+        queryset = Store.objects.prefetch_related(Prefetch('books', queryset=Book.objects.filter(name='Book1'), to_attr='book1_list'))
+        stores = []
+        for store in queryset:
+            books = [book.name for book in store.book1_list]
+            stores.append({'id': store.id, 'name': store.name, 'books': books})
+
+        return JsonResponse({'stores_with_prefetch_related' : stores }, status=200)
+