在python中解包大列表

Question

我必须打开这个大列表，把每个项目都放入db中。除这些数据外，一切正常。

I tried with:

([styles], [seasons], [day], [id]) = search_

但是我得到了这样的错误:

exception=ValueError('too many values to unpack (expected 4)')>

我使用这样的查询:

insert= "INSERT INTO cantina (styles,seasons,day,id) VALUES (?,?,?,?)"
db.execute(insert,(styles,seasons,day,id))

我知道我犯了一个错误，但是这里每一行有4个字段，似乎是正确的

search_ = [[["Redwine"], ['04'], ['01'], ['81535']],
[["Redwine"], ['04'], ['02'], ['81536']],
[["Redwine"], ['04'], ['03'], ['81537']],
[["Redwine"], ['04'], ['04'], ['81538']],
[["Redwine"], ['04'], ['05'], ['81539']],
[["Redwine"], ['04'], ['06'], ['81540']],
[["Redwine"], ['04'], ['07'], ['81541']],
[["Redwine"], ['04'], ['08'], ['81542']],
[["Redwine"], ['04'], ['09'], ['81543']],
[["Redwine"], ['04'], ['10'], ['81544']],
[["Redwine"], ['04'], ['11'], ['81545']],
[["Redwine"], ['04'], ['12'], ['81546']],
[["Redwine"], ['02'], ['01'], ['97179']],
[["Redwine"], ['02'], ['02'], ['97180']],
[["Redwine"], ['02'], ['03'], ['97181']],
[["Redwine"], ['02'], ['04'], ['97182']],
[["Redwine"], ['02'], ['05'], ['97183']],
[["Redwine"], ['02'], ['06'], ['97184']],
[["Redwine"], ['02'], ['07'], ['97185']],
[["Redwine"], ['02'], ['08'], ['97186']],
[["Redwine"], ['02'], ['09'], ['97187']],
[["Redwine"], ['02'], ['10'], ['97188']],
[["Redwine"], ['02'], ['11'], ['97189']],
[["Redwine"], ['02'], ['12'], ['97190']]]
([styles], [seasons], [day], [id]) = search_
insert= "INSERT INTO cantina (styles,seasons,day,id) VALUES (?,?,?,?)"
db.execute(insert,(styles,seasons,day,id))

编辑:

你好，Barmar，因为这个列表来自于我连接的另一个函数四个表:

def cantina ( cantina_id)
for ... in ...:
styles = 
season  = 
day = 
id = 
result.append([[styles], [season], [day], [id]]])
return result

和'append'只接受一个参数。

我必须处理一些数据，基于'cantina_id';将其添加到四个列表中并保存到db

Answer 1

您需要遍历search_并分别处理每一行。

insert= "INSERT INTO cantina (styles,seasons,day,id) VALUES (?,?,?,?)"
for row in search_:
([styles], [seasons], [day], [id]) = row
cur.execute(insert,(styles,seasons,day,id))
db.commit()

如果你改变你的cantina函数，使它不创建所有的单元素列表，你可以使用executemany()

def cantina ( cantina_id)
result = []
for ... in ...:
styles = 
season  = 
day = 
id = 
result.append([styles, season, day, id])
return result
search_ = cantina(some_id)
insert= "INSERT INTO cantina (styles,seasons,day,id) VALUES (?,?,?,?)"
cur.executemany(insert, search_)
db.commit()