为什么循环中的 Rake 任务只执行一次? [英] Why does a Rake task in a loop execute only once?

问题描述

我有连接到多个数据库的 rails 应用程序.我编写了如下所示的自定义 rake 任务:

I have rails application that connects to multiple databases. I wrote custom rake task that looks like this:

task :migrate_accounts_schema => [:environment] do |t|
  users = User.find :all, :conditions => ["state = 2"], :order => "id asc"
  users.each do |user|            
    if user.state == 2
      ActiveRecord::Base.establish_connection(
        :adapter  => "postgresql",
        :host     => user.database_host,
        :port     => user.database_port,
        :username => user.subdomain,
        :password => "#{user.database_password}",
        :database => user.database_name
      )
      Rake::Task["db:migrate"].invoke
    end
  end
end

问题是任务只为 users[0] 用户(集合中的第一个用户)执行 db:migrate 并且没有错误，只是静默停止...

The problem is that task executes db:migrate only for users[0] user (first user in collection) and there is no errors, just stoppes silently...

这是 rake --trace 的输出

Here's output from rake --trace

** Invoke app:migrate_accounts_schema (first_time)
** Invoke environment (first_time)
** Execute environment
** Execute app:migrate_accounts_schema    
** Invoke db:migrate (first_time)
** Invoke environment 
** Execute db:migrate
** Invoke db:schema:dump (first_time)
** Invoke environment 
** Execute db:schema:dump
** Invoke db:migrate 

我不知道为什么其他用户没有迁移.

I have no idea why the rest of users don't get migrated.

推荐答案

我忘记了确切的内部结构，但 Rake 的工作方式是 invoke 只会在需要时执行每个任务(换句话说一次).

I forgot the exact internals but the way Rake works is that invoke will only execute each task if it needs to (in other words once).

尝试在后续调用中调用 execute:

Try calling execute on subsequent calls:

Rake::Task["db:migrate"].execute

第一次通过循环时，您需要 invoke 因为它首先调用先决条件.

The first time through the loop you'll need invoke as it invokes the prerequisites first.

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