如何在Rails迁移中添加检查约束? [英] How do I add a check constraint in a Rails migration?

问题描述

我需要在Rails应用程序中的现有表中添加一个新的整数列.该列只能具有值1、2、3，因此我想向表/列添加检查约束.如何在Rails迁移中指定此约束?

I need to add a new integer column to an existing table in my Rails app. The column can only have values 1, 2, 3, so I'd like to add a check constraint to the table/column. How do I specify this constraint within a Rails migration?

推荐答案

Rails迁移没有提供任何添加约束的方法，但是您仍然可以通过迁移来实现，但只需将实际的SQL传递给execute()

Rails migration does not provide any way to add Constraints, but you can still do it via migration but by passing actual SQL to execute()

创建迁移文件:

ruby script/generate Migration AddConstraint

现在，在迁移文件中:

class AddConstraint < ActiveRecord::Migration
  def self.up
    execute "ALTER TABLE table_name ADD CONSTRAINT check_constraint_name CHECK (check_column_name IN (1, 2, 3) )"
  end

  def self.down
    execute "ALTER TABLE table_name DROP CONSTRAINT check_constraint_name"
  end
end

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