استعلامات ORM وتحميل العلاقات

from django.conf import settings
settings.configure(
    SECRET_KEY="synthetic-course-key",
    USE_I18N=False, USE_TZ=True,
    INSTALLED_APPS=[],
    DATABASES={"default": {"ENGINE": "django.db.backends.sqlite3", "NAME": ":memory:"}},
    DEFAULT_AUTO_FIELD="django.db.models.AutoField",
    ALLOWED_HOSTS=["testserver"],
)
import django
django.setup()

from django.db import connection, models

class Instructor(models.Model):
    name = models.CharField(max_length=60)
    class Meta:
        app_label = "lab"

class Course(models.Model):
    title = models.CharField(max_length=100)
    instructor = models.ForeignKey(Instructor, on_delete=models.PROTECT)
    class Meta:
        app_label = "lab"

with connection.schema_editor() as editor:
    editor.create_model(Instructor)
    editor.create_model(Course)
mira = Instructor.objects.create(name="Mira")
Course.objects.create(title="Django", instructor=mira)
Course.objects.create(title="Python", instructor=mira)
rows = Course.objects.select_related("instructor").order_by("title")
print([(row.title, row.instructor.name) for row in rows])

[('Django', 'Mira'), ('Python', 'Mira')]

تستخدم العينة ضم علاقة مفردة ولا تنشئ جداول تطبيق معد.

from django.conf import settings
settings.configure(
    SECRET_KEY="synthetic-course-key",
    USE_I18N=False, USE_TZ=True,
    INSTALLED_APPS=[],
    DATABASES={"default": {"ENGINE": "django.db.backends.sqlite3", "NAME": ":memory:"}},
    DEFAULT_AUTO_FIELD="django.db.models.AutoField",
    ALLOWED_HOSTS=["testserver"],
)
import django
django.setup()

from django.db import connection, models

class Course(models.Model):
    title = models.CharField(max_length=100)
    published = models.BooleanField(default=False)
    class Meta:
        app_label = "lab"

with connection.schema_editor() as editor:
    editor.create_model(Course)
Course.objects.create(title="Django", published=True)
Course.objects.create(title="Draft", published=False)
print(list(Course.objects.filter(published=True).order_by("title", "pk").values_list("title", flat=True)))

['Django']

تستبعد القاعدة المسودة قبل تحويل النتائج لقائمة وتختار العناوين فقط.