将某些对象从一个数据库迁移到另一个数据库 [英] Migrating some objects from one database to another

问题描述

我如何从一个数据库(开发，sqlite)中将一个用户及其所有关联(评论，帖子等)转储到另一个数据库(生产，mysql)中.

How can I dump one user with all his associations (comments, posts etc) from one database (development, sqlite) to insert it another (production, mysql).

我应该将其转储到yaml还是sql中?

Should I dump it into yaml or to sql or something else?

推荐答案

好.

God Save the YAML

我已经使用YAML从开发中转储到文件中并将其加载到我的产品中.由于ID为auto_increament，因此发生了ID更改的黑客事件.

I've used YAML dumping into file from development and loading this in my production. There was hack with id, that have changed, due it is auto_increament.

发展

user     = User.find X
posts    = user.posts
comments = user.comments
...
File.open("user.yml", "w")    { |f| f << YAML::dump(user) }
File.open("comments.yml", "w"){ |f| f << YAML::dump(comments) }
File.open("posts.yml", "w")   { |f| f << YAML::dump(posts) }
...

生产

user     = YAML::load_file("user.yml")
posts    = YAML::load_file("posts.yml")
comments = YAML::load_file("comments.yml")
new_user = user.clone.save # we should clone our object, because it isn't exist
posts.each do |p|
  post = p.clone
  post.user = new_user
  post.save
end
...

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