在unique_together模型上的Django .all（）查询

Question

我有一个模型，其中两个字段是唯一的：

class Servers(models.Model):
    server_id = models.IntegerField(db_column='server_id')
    nodename = models.CharField(max_length=40)
    tag_name = models.CharField(max_length=180)
    customer = models.ForeignKey(Customers, on_delete=models.CASCADE)
    os = models.ForeignKey(Operatingsystems, on_delete=models.CASCADE)
    active = models.IntegerField()

    class Meta:
        managed = False
        db_table = 'servers'
        unique_together = (('server_id', 'nodename'),)

当我运行以下查询时：

>>> Servers.objects.all()

我收到以下错误：

Traceback (most recent call last):
  File "<console>", line 1, in <module>
  File "/Users/rlthompson/.virtualenvs/venv/lib/python3.5/site-packages/django/db/models/query.py", line 232, in __repr__
    data = list(self[:REPR_OUTPUT_SIZE + 1])
  File "/Users/rlthompson/.virtualenvs/venv/lib/python3.5/site-packages/django/db/models/query.py", line 256, in __iter__
    self._fetch_all()
  File "/Users/rlthompson/.virtualenvs/venv/lib/python3.5/site-packages/django/db/models/query.py", line 1085, in _fetch_all
    self._result_cache = list(self.iterator())
  File "/Users/rlthompson/.virtualenvs/venv/lib/python3.5/site-packages/django/db/models/query.py", line 54, in __iter__
    results = compiler.execute_sql()
  File "/Users/rlthompson/.virtualenvs/venv/lib/python3.5/site-packages/django/db/models/sql/compiler.py", line 835, in execute_sql
    cursor.execute(sql, params)
  File "/Users/rlthompson/.virtualenvs/venv/lib/python3.5/site-packages/django/db/backends/utils.py", line 79, in execute
    return super(CursorDebugWrapper, self).execute(sql, params)
  File "/Users/rlthompson/.virtualenvs/venv/lib/python3.5/site-packages/django/db/backends/utils.py", line 64, in execute
    return self.cursor.execute(sql, params)
  File "/Users/rlthompson/.virtualenvs/venv/lib/python3.5/site-packages/django/db/utils.py", line 94, in __exit__
    six.reraise(dj_exc_type, dj_exc_value, traceback)
  File "/Users/rlthompson/.virtualenvs/venv/lib/python3.5/site-packages/django/utils/six.py", line 685, in reraise
    raise value.with_traceback(tb)
  File "/Users/rlthompson/.virtualenvs/venv/lib/python3.5/site-packages/django/db/backends/utils.py", line 64, in execute
    return self.cursor.execute(sql, params)
  File "/Users/rlthompson/.virtualenvs/venv/lib/python3.5/site-packages/django/db/backends/mysql/base.py", line 112, in execute
    return self.cursor.execute(query, args)
  File "/Users/rlthompson/.virtualenvs/venv/lib/python3.5/site-packages/MySQLdb/cursors.py", line 226, in execute
    self.errorhandler(self, exc, value)
  File "/Users/rlthompson/.virtualenvs/venv/lib/python3.5/site-packages/MySQLdb/connections.py", line 36, in defaulterrorhandler
    raise errorvalue
  File "/Users/rlthompson/.virtualenvs/venv/lib/python3.5/site-packages/MySQLdb/cursors.py", line 217, in execute
    res = self._query(query)
  File "/Users/rlthompson/.virtualenvs/venv/lib/python3.5/site-packages/MySQLdb/cursors.py", line 378, in _query
    rowcount = self._do_query(q)
  File "/Users/rlthompson/.virtualenvs/venv/lib/python3.5/site-packages/MySQLdb/cursors.py", line 341, in _do_query
    db.query(q)
  File "/Users/rlthompson/.virtualenvs/venv/lib/python3.5/site-packages/MySQLdb/connections.py", line 280, in query
    _mysql.connection.query(self, query)
django.db.utils.OperationalError: (1054, "Unknown column 'servers.id' in 'field list'")

我运行了makemigration并在数据库上migrate ，错误仍然存​​在。 所以我的问题是，如何对具有unique_together元集的数据库进行unique_together .all()查询？

Answer 1

您已managed设置为False 。 因此，Django不会在表上创建默认的主键（ id ）。

当您稍后尝试查询它时，Django ORM查找id并失败。

您需要至少有一个主键。 因此，请创建一个新字段或在现有字段上设置primary_key=True 。