Question

我在FK_Project表中添加了新列rw_item，这是Project_Master表的引用。

dp=# ALTER TABLE digital_publisher_rw_item ADD FK_Project int; 
ALTER TABLE


dp=# ALTER TABLE digital_publisher_rw_item ADD FOREIGN KEY(FK_Project) REFERENCES digital_publisher_project_master(id);
ALTER TABLE

现在我正在编写脚本以在FK_Project表中添加列rw_item的值。

但是得到以下异常，

异常：

>>> rw_item
<class 'dp.digital_publisher.models.rw_item'>
>>> rw_item.objects.all()
Traceback (most recent call last):
  File "<console>", line 1, in <module>
  File "/usr/lib/python2.6/site-packages/django/db/models/query.py", line 67, in __repr__
    data = list(self[:REPR_OUTPUT_SIZE + 1])
  File "/usr/lib/python2.6/site-packages/django/db/models/query.py", line 82, in __len__
    self._result_cache.extend(self._iter)
  File "/usr/lib/python2.6/site-packages/django/db/models/query.py", line 271, in iterator
    for row in compiler.results_iter():
  File "/usr/lib/python2.6/site-packages/django/db/models/sql/compiler.py", line 677, in results_iter
    for rows in self.execute_sql(MULTI):
  File "/usr/lib/python2.6/site-packages/django/db/models/sql/compiler.py", line 732, in execute_sql
    cursor.execute(sql, params)
  File "/usr/lib/python2.6/site-packages/django/db/backends/util.py", line 15, in execute
    return self.cursor.execute(sql, params)
  File "/usr/lib/python2.6/site-packages/django/db/backends/postgresql_psycopg2/base.py", line 44, in execute
    return self.cursor.execute(query, args)
DatabaseError: column digital_publisher_rw_item.FK_Project_id does not exist
LINE 1: ..."digital_publisher_rw_item"."deletion_date_time", "digital_p...
                                                             ^

Django models.py:

FK_Project = models.ForeignKey(Project_Master, null=True, blank=True)

如何处理？

Answer 1

由于您要手动添加字段，而不是像王尚所指出的那样使用Django's database migrations，因此您只需确保字段名称匹配即可。在这种情况下，请注意Django给出的确切错误：

DatabaseError: column digital_publisher_rw_item.FK_Project_id does not exist

它正在寻找FK_Project_id，而不是您添加的FK_Project。这是因为Django中的一个约定，它将_id追加到ForeignKey列的末尾。因此，您有两种处理方法：

重命名数据库中的列：ALTER TABLE digital_publisher_rw_item RENAME COLUMN FK_Project TO FK_Project_id
告诉Django使用您创建的列：FK_Project = models.ForeignKey(Project_Master, null=True, blank=True, db_column='FK_Project')

DatabaseError：列不存在

1 个答案: