多对多“通过代理” Django 中的关系
我的数据模型由三个主要实体组成：
class User(models.Model):
...
class Source(models.Model):
user = models.ForeignKey(User, related_name='iuser')
country = models.ForeignKey(Country, on_delete=models.DO_NOTHING)
description = models.CharField(max_length=100)
class Destination(models.Model):
user = models.ForeignKey(User, related_name='wuser')
country = models.ForeignKey(Country)
我正在尝试创建一个查询集，该查询集按用户（多对多）将所有源与目的地连接起来。通过这种方式，我将拥有一个包含每个用户所有可能的源/目标组合的表。 在 SQL 中，我将简单地连接三个表并从每个表中选择适当的信息。
我的问题是如何执行查询？如何访问查询数据？
My data model consists of three main entities:
class User(models.Model):
...
class Source(models.Model):
user = models.ForeignKey(User, related_name='iuser')
country = models.ForeignKey(Country, on_delete=models.DO_NOTHING)
description = models.CharField(max_length=100)
class Destination(models.Model):
user = models.ForeignKey(User, related_name='wuser')
country = models.ForeignKey(Country)
I am trying to create a queryset which is join all sources with destinations by user (many to many). In such a way I would have a table with all possible source/destination combinations for every user.
In SQL I would simple JOIN the three tables and select the appropriate information from each table.
My question is how to perform the query? How to access the query data?
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在 django 中，查询是在模型对象上完成的，它有很好的记录。查询或查询集是惰性的，当它们执行时，它们通常返回一个字典列表，列表中的每个字典都包含
字段，后跟值，例如：[ {'user':'albert','country':'美国和澳大利亚:)','description':'我的描述'},....]。每个用户的所有可能的源、目标组合？
我认为你必须使用 反向关系Ship 来完成此操作，例如：
请注意，我使用的是具有
ForeignKey的模型Source和Destination的较小大小写名称> 与的关系用户这将加入所有三个选项卡浏览其丰富的文档。编辑：
要进行内部联接，您必须告诉查询，这可以通过在反向模型名称上使用
__isnull=False来简单地实现：这应该执行内部联接加入所有表。
然后，您可以像之前一样使用
values选择要显示的内容。希望有帮助。 :)
In django queries are done on the model object, its well documented. The queries or querysets are lazy and when they execute they generally return a list of dict, each dict in the list contains the
fieldfollowed by thevalueeg:[{'user':'albert','country':'US and A :) ','description':'my description'},....].All possible source,destination combinations for every user?
I think you will have to use a reverse relation ship to get this done eg:
notice that i'm using the smaller case name of the models
SourceandDestinationwhich haveForeignKeyrelationship withUserthis will join all the three tabels go through the documentation its rich.Edit:
To make an inner join you will have to tell the query, this can be simply achieved by using
__isnull=Falseon the reverse model name:This should do a inner join on all the tables.
Then you can select what you want to display by using
valuesas earlier.hope that helps. :)