Python Django，外键的子集

我需要一种方法来选择外键的一个子集，但只限于一个子集。这是旧PHP数据库中使用的原始查询

SELECT a.name FROM character_trait b
LEFT JOIN trait a ON b.id_trait = a.id
WHERE b.id_character = 1
AND a.id_traittype = 10

所有的表格，character，trait，traittype和character_trait都是可用的，但是我不知道如何在Djando中实现它。我的想法是这样的

traits = CharacterTrait.objects.filter( id_character = character, id_trait.id_traittype = 10 )

但这只是给出了一个错误，关键字不能是表达式。我可以用一种非常难看的方式来做，只需使用这样的for循环来迭代得到的“traits”

traits = CharacterTrait.objects.filter( id_character = character )  

for t in traits:
    print t.id_trait.id_traittype.id

    if t.id_trait.id_traittype.id == 10:
        print "Got One"

编辑模块定义

class Trait(models.Model):
    id = models.IntegerField(primary_key=True)  # AutoField? 
    id_traittype = models.ForeignKey(Traittype, null=True, db_column = 'id_traittype')

    name = models.CharField(max_length=32)

    class Meta:
        managed = False
        db_table = 'trait'

    def __unicode__(self):
                return self.name

class Traittype(models.Model):
    id = models.IntegerField(primary_key=True)  # AutoField?
    name = models.CharField(max_length=64)

    class Meta:
        managed = False
        db_table = 'traittype'

    def __unicode__(self):
                return self.name    

class Trait(models.Model):
    id = models.IntegerField(primary_key=True)  # AutoField? 
    id_traittype = models.ForeignKey(Traittype, null=True, db_column = 'id_traittype')

    name = models.CharField(max_length=32)

    class Meta:
        managed = False
        db_table = 'trait'

    def __unicode__(self):
                return self.name

class CharacterTrait(models.Model):
    id = models.IntegerField(primary_key=True)  # AutoField?
    ##id_character = models.IntegerField()
    ## id_trait = models.IntegerField()
    id_character = models.ForeignKey(Werewolfcharacter, null=True, db_column = 'id_character')
    id_trait     = models.ForeignKey(Trait,             null=True, db_column = 'id_trait')

    class Meta:
        managed = False
        db_table = 'character_trait'

    def __unicode__(self):
                return self.id_trait.name  

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一个简单的可能性，因为您的PHP代码中可能已经有了正确的SQL，就是简单地执行

traits = CharacterTrait.objects.filter( id_character = character).filter(id_trait__id_traittype = 10 )

但回顾一些代码

traits = CharacterTrait.objects.filter( id_character = character, id_trait__id_traittype = 10 )

---

应该足够了，这里的关键是更换。使用dm03514建议的_uu

时，您应该阅读上的文档。您需要使用双下划线语法：

CharacterTrait.objects.filter(id_character=character, id_trait__id_traittype=10)

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你能发布你的模型定义吗？django filter键盘使用分数下的_u2来跨越fk relationshipsDone，增加了模块。