Ruby-on-rails 我可以将默认值传递给 rails 生成迁移吗？
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Can I pass default value to rails generate migration?
提问by Leantraxxx
I want to know if I can pass a default valueto the rails g migrationcommand. Something like:
我想知道是否可以将默认值传递给rails g migration命令。就像是：
$ rails generate migration add_disabled_to_users disabled:boolean:false #where false is default value for disabled attribute
in order to generate:
为了生成：
class AddDisabledToUsers < ActiveRecord::Migration
def change
add_column :users, :disabled, :boolean, default: false
end
end
采纳答案by Benj
You can't: https://guides.rubyonrails.org/active_record_migrations.html#column-modifiers
你不能：https: //guides.rubyonrails.org/active_record_migrations.html#column-modifiers
null and default cannot be specified via command line.
不能通过命令行指定 null 和 default。
回答by Deepti Kakade
Rails migration generator does not handle default values, but after generation of migration file you should update migration file with following code
Rails 迁移生成器不处理默认值，但在生成迁移文件后，您应该使用以下代码更新迁移文件
add_column :users, :disabled, :boolean, default: false
you can also see this link - http://api.rubyonrails.org/classes/ActiveRecord/Migration.html
你也可以看到这个链接 - http://api.rubyonrails.org/classes/ActiveRecord/Migration.html
回答by Subhash Chandra
Default migration generator in Rails does not handle default values, there is no way around as of now to specify default value defined through terminal in rails migration.
Rails 中的默认迁移生成器不处理默认值，目前还没有办法在 rails 迁移中指定通过终端定义的默认值。
you would like to follow below steps in order to achieve what you want
你想按照以下步骤来实现你想要的
1). Execute
1）。执行
$ rails generate migration add_disabled_to_users disabled:boolean
2). Set the new column value to TRUE/FALSE by editing the new migration file created.
2）。通过编辑创建的新迁移文件将新列值设置为 TRUE/FALSE。
class AddDisabledToUsers < ActiveRecord::Migration
def change
add_column :users, :disabled, :boolean, default: false
end
end
3). Run above generated migration by Executing.
3）。通过执行运行上面生成的迁移。
$ rake db:migrate
回答by Andrew Grimm
Rails 3.2 does not seem to support any kind of command line type modifier based on http://guides.rubyonrails.org/v3.2/migrations.html
Rails 3.2 似乎不支持任何基于http://guides.rubyonrails.org/v3.2/migrations.html的命令行类型修饰符
The documentation for Rails 4.1 refers to type modifiersbut the documentation for Rails 3.2does not mention the word "modifier" in the page.
