TypeError: Cannot create a consistent MRO for bases Mixin, object

Question

我正在尝试向 Django QuerySet 添加一个 explain() 方法，但收到 MRO 错误：

File ".../mixin.py", line 10, in <module>

    QuerySet.__bases__ += (QuerySetExplainMixin,)
TypeError: Cannot create a consistent method resolution
order (MRO) for bases QuerySetExplainMixin, object

mixin 和我添加的代码：

from django.db import connections
from django.db.models.query import QuerySet

class QuerySetExplainMixin:
    def explain(self):
        cursor = connections[self.db].cursor()
        query, params = self.query.sql_with_params()
        cursor.execute('explain %s' % query, params)
        return '\n'.join(r[0] for r in cursor.fetchall())

QuerySet.__bases__ += (QuerySetExplainMixin,)

（mixin 的致谢：）

Answer 1

此代码是为 Python 编写的 2，这就是为什么您在 Python 中遇到冲突的原因 3，除了下面我看不到在 QuerySet 上设置新方法的其他方法对象：

from django.db import connections
from django.db.models.query import QuerySet

def explain(self):
    cursor = connections[self.db].cursor()
    query, params = self.query.sql_with_params()
    cursor.execute('explain %s' % query, params)
    return '\n'.join(r[0] for r in cursor.fetchall())

type.__setattr__(QuerySet, 'explain', explain)

希望对您有所帮助

TypeError: Cannot create a consistent MRO for bases Mixin, object

TypeError: Cannot create a consistent MRO for bases Mixin, object

django

method-resolution-order

python-3.x