在Rails 5中似乎没有太多关于UUID
s的文档。我发现的是这段代码:
create_table :users, id: :uuid do |t|
t.string :name
end
如果你正在创建一个表,那么这很有用,但是如果你要更新已经存在的表怎么办?
如何在表格中添加UUID
列?
要从默认ID迁移到使用uuid,请尝试像这样编写迁移:
class ChangeProjectsPrimaryKey < ActiveRecord::Migration
def change
add_column :projects, :uuid, :uuid, default: "uuid_generate_v4()", null: false
change_table :projects do |t|
t.remove :id
t.rename :uuid, :id
end
execute "ALTER TABLE projects ADD PRIMARY KEY (id);"
end
end
以下是将uuid
列添加到现有Rails表的方法。
class AddUuidToContacts < ActiveRecord::Migration[5.1]
def change
enable_extension 'uuid-ossp' # => http://theworkaround.com/2015/06/12/using-uuids-in-rails.html#postgresql
add_column :contacts, :uuid, :uuid, default: "uuid_generate_v4()", null: false
execute "ALTER TABLE contacts ADD PRIMARY KEY (uuid);"
end
end
如果您忘记添加enable_extension 'uuid-ossp'
,您将收到以下错误:
PG :: UndefinedFunction:错误:函数uuid_generate_v4()不存在ActiveRecord :: StatementInvalid:PG :: UndefinedFunction:ERROR:函数uuid_generate_v4()不存在