CODEWITHSUNDEEP
jquerydjangodjango-rest-framework
mehdi
mehdi

Reputation: 1150

in below code what does ordered_by("?") do?

I'm new in django , javascripts , jquery , css and etc . In a project on the Internet I have seen the following code and i try to found whats going on with this project , but i cant understood what does ordered_by("?")in views.py do.any help? for more imformation : this project is about marketing site that in home page will show stuff from database. tnx

urls.py:

path('', product.views.home),

models.py:

class Product(models.Model):
    name = models.CharField(max_length=70, verbose_name='نام ')
    subtitle = models.CharField(max_length=70, null=True, blank=True, verbose_name='عنوان فرعی ')
    code = models.CharField(max_length=30, null=True, blank=True, verbose_name='کد محصول')
    father = models.ForeignKey("self", related_name="children", null=True, blank=True, on_delete=models.CASCADE,
                               verbose_name="پدر")
    have_children = models.BooleanField(default=False, verbose_name="فروش به صورت فصلی")
    og_description = models.CharField(max_length=250, null=True, blank=True)
    company = models.ForeignKey(Company, verbose_name='شرکت ', null=True, blank=True,
                                related_name='products', on_delete=models.CASCADE)

    price = models.IntegerField(default=0, null=True, blank=True, verbose_name='قیمت به ریال')

    # grade = models.ForeignKey(Grade, related_name='products', null=True, blank=True, verbose_name='پایه تحصیلی')
    brochure = models.ImageField(upload_to='brochure', null=True, blank=True, verbose_name='بروشور')
    photo_id = models.CharField(max_length=100, null=True, blank=True, verbose_name='آی دی تلگرام عکس')
    video_id = models.CharField(max_length=100, null=True, blank=True, verbose_name='آی دی تلگرام ویدئو')
    video = models.FileField(upload_to='videos', null=True, blank=True, verbose_name='دموی ویدیویی')
    introduction = models.TextField(null=True, blank=True, verbose_name='معرفی اولیه')
    thumbnail = models.ImageField(upload_to='thumbnail', null=True, blank=True, verbose_name='تامب نیل')
    link = models.URLField(max_length=300, null=True, blank=True, validators=[URLValidator()],
                           verbose_name='آدرس فروش در وب سایت')
    label_1 = models.CharField(max_length=30, null=True, blank=True)
    label_2 = models.CharField(max_length=30, null=True, blank=True)

    physical = models.BooleanField(default=False, verbose_name="محصول فیزیکی")
    includes_discount_code = models.BooleanField(default=False, verbose_name="شامل کد تخفیف")
    includes_download_file = models.BooleanField(default=False, verbose_name="شامل فایل برای دانلود")

    like_count = models.PositiveIntegerField(null=True, blank=True, verbose_name='تعداد لایک')
    average_score = models.FloatField(null=True, blank=True, verbose_name="میانگین امتیاز")
    buy_count = models.PositiveIntegerField(null=True, blank=True, verbose_name="تعداد فروش")
    buy_help_text = models.TextField(blank=True, null=True, verbose_name="راهنمای خرید")
    use_help_text = models.TextField(blank=True, null=True, verbose_name="راهنمای استفاده")
    promote_text = models.TextField(blank=True, null=True, verbose_name="معرفی مفصل")
    limit_buy = models.PositiveIntegerField(default=1, verbose_name="محدودیت خرید")
    # data = JSONField(null=True, blank=True, verbose_name="مشخصات")

    available = models.BooleanField(default=True, verbose_name="قابل استفاده")

serializers.py :

class MiniProductSerializers(serializers.ModelSerializer):

    class Meta:
        model = Product
        fields = (
            "have_children",
            "thumbnail",
            "limit_buy",
            "subtitle",
            "brochure",
            "price",
            "name",
            "id",
        )

views.py:

def home(request):
    ref = request.GET.get("ref")
    if ref:
        ReferenceLink.objects.create(page_name="اصلی", reference=ref)

    return render(request, 'home/home.html', {
        'company_list': MiniCompanySerializers(Company.objects.all(), many=True).data,
        'cat_1': MiniProductSerializers(Product.objs.filter(productcategory__category__father_id=1).order_by("?")[:10], many=True).data,
        'cat_2': MiniProductSerializers(Product.objs.filter(productcategory__category__father_id=2).order_by("?")[:10], many=True).data,
        'cat_3': MiniProductSerializers(Product.objs.filter(productcategory__category__father_id=3).order_by("?")[:10], many=True).data,
        'cat_4': MiniProductSerializers(Product.objs.filter(productcategory__category__father_id=4).order_by("?")[:10], many=True).data,
        'cat_5': MiniProductSerializers(Product.objs.filter(productcategory__category__father_id=5).order_by("?")[:10], many=True).data,
        'blog_posts': MiniPostSerializers(Post.objects.filter(home_page__exact=True), many=True).data,
    })

Upvotes: 0

Views: 33

Answers (2)

Atley Varghese
Atley Varghese

Reputation: 576

Please see the Django official doc: https://docs.djangoproject.com/en/2.1/ref/models/querysets/#order-by

ModelName.objects.all().order_by('id')

This will return the queryset ordered ascending by the value of id.

ModelName.objects.all().order_by('-id')

This will return the queryset ordered in descending by the value of id.

    ModelName.objects.all().order_by('?')

To order randomly, use "?", order_by('?') queries may be expensive and slow, depending on the database backend you’re using.

Upvotes: 1

funnydman
funnydman

Reputation: 11376

ordered_by("?") - just selects random items from a set. Keep in mind that this statement can take a too long time to compute and sometimes not preferably. Take a look at the docs:

Note: order_by('?') queries may be expensive and slow, depending on the database backend you’re using.

Upvotes: 1

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