如何覆盖自定义数据库适配器的 rake 任务?

问题描述

我编写了一个自定义数据库适配器，它在 Rails 服务器运行时可以正确有效地工作.我现在想添加用于创建、删除和迁移数据库的常用 rake 任务定义.

I've written a custom database adapter that works correctly and effectively when a rails server is running. I would now like to add the usual rake task definitions for creating, dropping and migrating the database.

我想实施:

db:[drop|create|migrate]

我如何将这些定义与我的 gem 打包在一起，以便它们覆盖使用 gem 的任何人的默认定义?

How do I package these definitions with my gem so that they override the default ones for anyone who uses the gem?

我查看了其他适配器的源代码，但所有 rake 任务逻辑似乎都融入了 active_record 本身，每个任务只是打开了适配器名称.

I looked through the source of other adapters but all the rake task logic appears to be baked into active_record itself, each task just switches on the adapter name.

推荐答案

这可以通过:

# somewhere in your gem's tasks
Rake::Task['db:create'].clear

# then re-define
namespace 'db' do
  task 'create' do
    # ...
  end
end

当 Take::Task#[] 无法解析任务时 它将失败.如果您的任务有时存在，您可能想要:

When Take::Task#[] can't resolve a task it will fail.If your tasks sometimes exists, you might want to:

task_exists = Rake.application.tasks.any? { |t| t.name == 'db:create' }
Rake::Task['db:create'].clear if task_exists

如果您想将任务添加到现有的 rake 任务，请使用 enhance.

If you want to add tasks to an existing rake task, use enhance.

Rake::Task['db:create'].enhance do
  Rake::Task['db:after_create'].invoke
end

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