Question

这是我想要关联的模型。我希望收藏品以出现的形式出现。

class Collection(models.Model):
    id = models.AutoField(primary_key=True, null=True)
    code = models.CharField(max_length=100, null=True, blank=True)
    address = models.CharField(max_length=100, null=True, blank=True)
    collection_name = models.CharField(max_length=100)

    def __unicode__(self):
        return self.collection_name

    class Meta:
        db_table = u'collection'
        ordering = ('collection_name',)

class Occurrence(models.Model):
    id = models.AutoField(primary_key=True, null=True)
    reference = models.IntegerField(null=True, blank=True, editable=False)
    collection = models.ForeignKey(Collection, null=True, blank=True, unique=True),
    modified = models.DateTimeField(null=True, blank=True, auto_now=True)
    class Meta:
         db_table = u'occurrence'

每次我去检查Occurrence对象时都会收到此错误

 TemplateSyntaxError at /admin/hotiapp/occurrence/
 Caught an exception while rendering: column occurrence.collection_id does not exist
 LINE 1: ...LECT "occurrence"."id", "occurrence"."reference", "occurrenc..

每次我尝试添加新的事件对象时都会出现此错误

 ProgrammingError at /admin/hotiapp/occurrence/add/
 column occurrence.collection_id does not exist
 LINE 1: SELECT (1) AS "a" FROM "occurrence" WHERE "occurrence"."coll...

我做错了什么？或者ForeignKey如何运作？

Answer 1

问题是您添加ForeignKey后没有更新数据库表定义。正如文档明确指出的那样，syncdb不会为您执行此操作。您需要手动更新SQL，或使用像South这样的工具。

Answer 2

你确定你的意思

collection = models.ForeignKey(Collection, null=True, blank=True, unique=True),

可空和独特？在某些数据库中可能无法实现这一点。

通常，这里的唯一约束似乎没有多大意义。

您是否试图强制建立一对一的关系？使用OneToOneField。 http://docs.djangoproject.com/en/1.1/ref/models/fields/#django.db.models.OneToOneField

Django ForeignKey TemplateSyntaxError和ProgrammingError

2 个答案: