为什么 peewee 将 select 列强制为整数

Question

我不能在 peewee 中使用 sqlite 函数 group_concat()。这是完整的片段。不知何故，peewee 想将 group_concat() 的结果转换为整数，而它是字符串 ("1,2")。找不到压制的方法了

from peewee import *

db = SqliteDatabase(':memory:')

class Test(Model):
    name = CharField()
    score = IntegerField()

    class Meta:
        database = db

db.create_tables([Test])
Test.create(name='A', score=1).save()
Test.create(name='A', score=2).save()

#select name, group_concat(score) from Test group by name
for t in Test.select(Test.name, fn.group_concat(Test.score)).order_by(Test.name):
    pass

它产生以下错误：

Traceback (most recent call last):
File "C:\Users\u_tem0m\Dropbox\Wrk\sgo\broken.py", line 17, in <module>  
  for t in Test.select(Test.name, fn.group_concat(Test.score)).order_by(Test.name):  
File "C:\Program Files\Python 3.5\lib\site-packages\peewee.py", line 1938, in next
  obj = self.qrw.iterate()  
File "C:\Program Files\Python 3.5\lib\site-packages\peewee.py", line 1995, in iterate  
  return self.process_row(row)  
File "C:\Program Files\Python 3.5\lib\site-packages\peewee.py", line 2070, in process_row  
  setattr(instance, column, func(row[i]))  
File "C:\Program Files\Python 3.5\lib\site-packages\peewee.py", line 874, in python_value  
  return value if value is None else self.coerce(value)  
ValueError: invalid literal for int() with base 10: '1,2'

Answer 1

刚刚发现 fn.group_concat(""+Test.score) 的结果没有转换为整数。但我认为结果 sql 可能不太理想

SELECT "t1"."name", group_concat(? + "t1"."score") AS allscore FROM "test" AS t1 ORDER BY "t1"."name" ['']

有人知道更优雅的方法吗？

Answer 2

尝试在您对 group_concat 的呼叫中添加 coerce(False)：

query = (Test
         .select(Test.name, fn.GROUP_CONCAT(Test.score).coerce(False))
         .order_by(Test.name))
for t in query:
    pass

Peewee 发现 Test.score 是一个整型字段，因此每当对该列调用函数时，Peewee 都会尝试将结果转换回 int。问题是 group_concat return 是一个字符串，所以我们必须告诉 Peewee 不要弄乱 return 值。

为什么 peewee 将 select 列强制为整数

Why peewee coerces select column to integer

python

sqlite

peewee