不能在Ruby Sequel中'删除'

Question

我从Ruby的Sequel数据库库开始.

给出以下代码:

require 'sequel'
db = Sequel.connect('sqlite://users.db')
users = db[:users]
users.first.delete

Ruby抛出错误:

'delete' : wrong number of arguments (0 for 1) (ArgumentError)

我可以删除多条记录,但.first.delete不起作用.怎么了？

Answer 1

db[:users]给你一个Sequel::SQLite::Dataset.没有任何参数的users.first方法会将用户作为Hash对象.现在你正在打电话Hash#delete,这需要一个参数.但你并没有传递那个论点.因此它抱怨.

而是做如下:

# if you want to delete the the first matching argument of any specific
# attribute/db column
db[:users].filter(:key => 1).delete
# or if you want to delete the first record from db
db[:users].limit(1).delete

也阅读此#drop方法.