Question

我知道我不是第一个提出这个问题的人，但我无法找到解决方案。我有以下型号：

class Size(models.Model):
    id = models.IntegerField()
    size = models.CharField(max_length=255)
    country = models.CharField(max_length=255)

    class Meta:
        db_table = 'size'


class Orders(models.Model):
    id = models.IntegerField()
    order_id = models.CharField(max_length=255)
    date = models.DateTimeField()
    status = models.CharField(max_length=1)
    brand_id = models.IntegerField()
    user_id = models.IntegerField()
    shop_id = models.IntegerField()
    item_id = models.IntegerField()
    category_id = models.IntegerField()
    item_gender = models.CharField(max_length=1)
    return_reason = models.CharField(max_length=255)
    size = models.ForeignKey(Size)

    class Meta:
        db_table = 'orders'

我尝试使用反向查找，因为它描述了this

sizes = Size.objects.using('mysql_db').filter(orders__user_id=6)

错误：

Cannot resolve keyword 'orders' into field. Choices are: country, id, size
Request Method: GET
Request URL:    http://127.0.0.1:8000/dictionary/types/
Django Version: 1.8.2
Exception Type: FieldError
Exception Value:    
Cannot resolve keyword 'orders' into field. Choices are: country, id, size
Exception Location: /Users/.../env/lib/python3.4/site-packages/django/db/models/sql/query.py in names_to_path, line 1391
Python Executable:  /Users/.../env/bin/python
Python Version: 3.4.3

Answer 1

我已经验证您发布的查询是按原样运行的，问题出在代码的其他位置。你运行makemigrations并迁移吗？您可以找到工作代码示例here：

models.py

from django.db import models

# Create your models here.
class Size(models.Model):
    id = models.IntegerField(primary_key=True)
    size = models.CharField(max_length=255)
    country = models.CharField(max_length=255)

    class Meta:
        db_table = 'size'


class Orders(models.Model):
    id = models.IntegerField(unique=True,primary_key=True)
    order_id = models.CharField(max_length=255)
    date = models.DateTimeField()
    status = models.CharField(max_length=1)
    brand_id = models.IntegerField()
    user_id = models.IntegerField(default = 6)
    shop_id = models.IntegerField()
    item_id = models.IntegerField()
    category_id = models.IntegerField()
    item_gender = models.CharField(max_length=1)
    return_reason = models.CharField(max_length=255)
    size = models.ForeignKey(Size)

    class Meta:
        db_table = 'orders'

views.py

class ReverseFK(ListView):
    model = Size
    def get_queryset(self):
        Size.objects.create()
        return Size.objects.filter(orders__user_id=5)

Answer 2

变种之一

sizes = [item.size for item in Orders.objects.filter(user_id=6)]

但是，您应该使用select_related将SQL查询量减少到一个。

否则您将隐式执行n + 1次查询。

Django REST框架中的反向关系查找 - FieldError：无法将关键字解析为字段

2 个答案: