Rails 迁移:检索当前迁移版本的最佳方式 [英] Rails migration: best way to retrieve current migration version

问题描述

有没有什么好的方法可以检索迁移版本号?

Is there good way to retrieve migration version number?

我需要在模型中实现一种方法，该方法在特定迁移版本内外表现不同.

I need to implement a method in a model which behave differently on and beyond a specific migration version.

我发现连接适配器中的 assert_migrated_upto_version 正在从数据库中检索版本但找不到其他版本.

I found assume_migrated_upto_version in connection adapter is retrieving version from database but can't find others.

背景:我试图从表 A 中删除两列，想将它们移到表 B 中，并从表 A 中添加与表 B 的关联.

Background: I'm trying to remove two columns from table A, want to move them into table B, and add association to the table B from the table A.

在此更改期间，我需要访问这两列.但在那之后，我想为这些列添加代理方法以实现兼容性.

During this change, I need to access these two columns. but after that, I want to add proxy method for these columns for compatibility.

推荐答案

Rails 5.2 及更高版本:

Rails 5.2 and higher:

> ApplicationRecord.connection.migration_context.current_version
   (0.3ms)  SELECT "schema_migrations"."version" FROM "schema_migrations" ORDER BY "schema_migrations"."version" ASC
=> 20200510093804

> ApplicationRecord.connection.migration_context.get_all_versions
   (0.3ms)  SELECT "schema_migrations"."version" FROM "schema_migrations" ORDER BY "schema_migrations"."version" ASC
=> [20191005164928,
    20191006111502,
   ...

Rails 到 5.1.7:

> ActiveRecord::Migrator.current_version
   (0.2ms)  SELECT "schema_migrations"."version" FROM "schema_migrations" 
=> 20120110085802

> ActiveRecord::Migrator.get_all_versions
   (0.3ms)  SELECT "schema_migrations"."version" FROM "schema_migrations" 
=> [20111114121610,
    20111115091108,
   ...

这篇关于Rails 迁移:检索当前迁移版本的最佳方式的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！