Django:prefetch_related()是否遵循反向关系查找? [英] Django: Does prefetch_related() follow reverse relationship lookup?
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问题描述
我在trunk中已经在django 1.4中尝试过prefetch_related(),不能使其预取反向查找。
我的简化模型(每本书有很多价格):
class Book(models.Model):
#some fields
class价格(models.Model):
book = models.ForeignKey(Book)
我的观点查询:
books = Book.objects.prefetch_related('price')
/ pre>
然后,我得到了AttributeError消息:
AttributeError :无法在Book对象上找到'price','price'是prefetch_related()的无效参数
如何使其工作?
谢谢。解决方案定义相关名称:
class Price(models.Model):
book = models.ForeignKey(Book,related_name ='prices')
然后使用它:
books = Book.objects。 prefetch_related('price')
I've tried prefetch_related() in django 1.4 from trunk and can't make it to prefetch reverse lookup.
My simplified models (each book has many prices):
class Book(models.Model): # some fields class Price(models.Model): book = models.ForeignKey(Book)
My view's query:
books = Book.objects.prefetch_related('price')
Then, I got the AttributeError message:
AttributeError: Cannot find 'price' on Book object, 'price' is an invalid parameter to prefetch_related()
How to make it work? Thanks.
解决方案Define a related name:
class Price(models.Model): book = models.ForeignKey(Book, related_name='prices')
and then use it:
books = Book.objects.prefetch_related('prices')
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