Flask ORM使用Count报错 Cannot compile Column object until its ‘name‘ is assigned.

我不是女神ヾ 2022-11-19 04:23 107阅读 0赞

# 问题描述 #

1.  使用Flask ORM 编写model,使用基础类 BaseModel, 而后使用排序 order\_by
2.  使用 count 进行查询时，报错

Cannot compile Column object until its 'name' is assigned.

## 解决方案 ##

1.  不使用排序，删除 `__mapper_args__`
2.  将需要排序的属性和\_\_mapper\_args\_\_ ，放到继承了 db.Model 的类中，这样既能保证排序能正常使用，count 也不报错

### models ###

class BaseModel:
        id = db.Column(db.Integer, primary_key=True, autoincrement=True, comment="主键")
        create_time = db.Column(db.DateTime, default=datetime.now, comment="创建时间")
        update_time = db.Column(db.DateTime, default=datetime.now, onupdate=datetime.now, comment="更新时间")
        is_deleted = db.Column(db.Boolean, default=False)
    
        __mapper_args__ = {
            "order_by": update_time.desc()
        }
    
    
    class WorkTicket(BaseModel, db.Model):
        __tablename__ = 'work_ticket'
        id = db.Column(db.String(255), primary_key=True, comment="主键")
        create_people = db.Column(db.String(255), comment="用户id")

### 使用查询 ###

counts = WorkTicket.query.filter_by(**self.GET, is_deleted=False).count()

- 报错信息
        name = self._fallback_column_name(column)
      File "D:\environment\python3.6\lib\site-packages\sqlalchemy\sql\compiler.py", line 864, in _fallback_column_name
        "Cannot compile Column object until " "its 'name' is assigned."
    sqlalchemy.exc.CompileError: Cannot compile Column object until its 'name' is assigned.