所以我在我的用户模型上有一个性别列,它当前是一个字符串,我想把它改成一个整数并使其成为男'1',而女'0'因为它现在是男性“M”女性“ F”。运行此迁移时:
class ChangeGenderToIntegerOnUser < ActiveRecord::Migration
def change
change_column :users, :gender, 'integer USING CAST(gender AS integer)'
end
end
我收到以下错误:
错误消息:
PG::InvalidTextRepresentation: ERROR: invalid input syntax for integer: "M"
: ALTER TABLE "users" ALTER COLUMN "gender" TYPE integer USING CAST(gender AS integer)/usr/local/rvm/gems/ruby-2.0.0-p247/gems/activerecord-4.0.0.rc1/lib/active_record/connection_adapters/postgresql/database_statements.rb:128:in `exec'
如何正确地将性别更改为整数?
提前致谢!
答案 0 :(得分:11)
您需要先将值M转换为1,将F转换为0,然后更改列类型。
class ChangeGenderToIntegerOnUser < ActiveRecord::Migration
def change
User.where(gender: 'M').update_all(gender: 1)
User.where(gender: 'F').update_all(gender: 0)
change_column :users, :gender, 'integer USING CAST(gender AS integer)'
end
end