prefetch_related not working in django?

S

Semyon Pyatnitsky2017-05-03 20:33:07

Django

Semyon Pyatnitsky, 2017-05-03 20:33:07

There are 3 models

from django.db import models

from django.utils import timezone

class Contact(models.Model):
    IDContact = models.IntegerField(primary_key=True)
    NameContact = models.CharField(max_length=255)
    FamilyContact = models.CharField(max_length=255)
    SoNameContact = models.CharField(max_length=255)
    class Meta:
        db_table = 'contacts'


class Client(models.Model):

    ClientId = models.IntegerField(primary_key=True)
    ClientName = models.CharField(max_length=255)
    contacts = models.ManyToManyField('Contact', through='Workplace')

    class Meta:
        db_table = 'clients'

class Workplace(models.Model):

    client = models.ForeignKey('Client', db_column='wpClientId')
    contact = models.ForeignKey('Contact', db_column='wpContactId')

    class Meta:
        db_table = 'Workplace'


# Create your models here.
class Post(models.Model):
    author = models.ForeignKey('auth.User')
    category = models.ForeignKey('PostCategory')
    title = models.CharField(max_length=200)
    text = models.TextField()
    created_date = models.DateTimeField(
            default=timezone.now)
    published_date = models.DateTimeField(
            blank=True, null=True)

    def publish(self):
        self.published_date = timezone.now()
        self.save()

    def __str__(self):
        return self.title


class PostCategory(models.Model):
    name = models.CharField(max_length=200)

    created_date = models.DateTimeField(
            default=timezone.now)
    published_date = models.DateTimeField(
            blank=True, null=True)
    def __str__(self):
        return self.name

I'm trying to display all clients and their contacts (individuals)

def post_list(request):
    clients = Client.objects.prefetch_related('contacts').all()
    return render(request, 'blog/post_list.html', {'clients': clients})

<html>
<body>
    {% for client in clients %}
        <div>
            <p><a href="">{{ client.ClientName }}</a></p>
        {% for contact in client.contacts.all %}
            {{ contact.NameContact }}
             {% endfor %}
        </div>

    {% endfor %}
</body>
</html>

But only displays clients. in Yii2 and Laravel, it was solved by specifying the connection in the with() method. in rails, this is includes(). Help))
Yii2 builds correctly through with 2 requests and conclusions on the screenshots. the numbers after the name are the ids of the contacts that are associated with the counterparty in the workplace table.

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2 answer(s)

S

sim3x, 2017-05-03
@sim3x

{% for contact in client.contacts.all %}

N

Neoliz, 2017-05-29
@timofeydeys

def post_list(request):
    clients = Client.objects.prefetch_related('contacts').all()
    return render(request, 'blog/post_list.html', {'clients': clients})

It should be so))

def post_list(request):
    clients = Client.objects.all().prefetch_related('contacts')
    return render(request, 'blog/post_list.html', {'clients': clients})

And if you want to make a nested query, according to a specific queryset, then like this:

from django.db.models import Prefetch

def post_list(request):
    clients = Client.objects.all().prefetch_related(Prefetch('contacts', queryset=Contanct.objects.all()))  # В Queryset скармливаешь просто queryset и делается вложенный запрос.
    return render(request, 'blog/post_list.html', {'clients': clients})