[英]Django: Non-primary Foreign Key object can't access related model instance
我是 Django 的新手。 我在models.py中有 2 类tech_system和设备
class tech_system(models.Model):
id_tech_system = models.BigAutoField(db_column='ID_tech_system', primary_key=True)
system_descript_short = models.CharField(max_length=255, blank=True, null=True)
#More field here
tech_system_code = models.CharField(unique=True, max_length=40)
class Meta:
managed = False
db_table = 'tech_system'
def __str__(self):
return self.system_descript_short
class equiptment(models.Model):
id_thietbi = models.BigAutoField(db_column='ID_thietbi', primary_key=True)
tech_system_code = models.ForeignKey('tech_system', models.DO_NOTHING, db_column="tech_system_code", blank=True, null=True)
class Meta:
managed = False
db_table = 'equiptment'
我使用python shell,设备模型对象无法访问相关的tech_system模型实例。 我得到错误匹配查询不存在。 我想得到值obj1.equiptment.tech_system_code.system_descript_short 。 我能怎么做?
谢谢你。
>>> obj1 = equiptment.objects.first()
>>> obj1.tech_system_code_id
'530'
>>> obj1.tech_system_code
Traceback (most recent call last):
File "D:\Dev1\env1\lib\site-packages\django\db\models\fields\related_descriptors.py", line 173, in __get__
rel_obj = self.field.get_cached_value(instance)
File "D:\Dev1\env1\lib\site-packages\django\db\models\fields\mixins.py", line 15, in get_cached_value
return instance._state.fields_cache[cache_name]
KeyError: 'tech_system_code'
During handling of the above exception, another exception occurred:
Traceback (most recent call last):
File "<console>", line 1, in <module>
File "D:\Dev1\env1\lib\site-packages\django\db\models\fields\related_descriptors.py", line 187, in __get__
rel_obj = self.get_object(instance)
File "D:\Dev1\env1\lib\site-packages\django\db\models\fields\related_descriptors.py", line 154, in get_object
return qs.get(self.field.get_reverse_related_filter(instance))
File "D:\Dev1\env1\lib\site-packages\django\db\models\query.py", line 437, in get
self.model._meta.object_name
app.models.tech_system.DoesNotExist: tech_system matching query does not exist.
我发现 tech_system_code 记录被分配为 str 类型,而不是设备模型中的对象。 导入数据库的记录值不正确。 谢谢你的帮助。
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