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Rails的列有 「：引用」 - 混亂

2012-11-14 43 views
0

我有一個用戶表 「belongs_to的：user_category」，並user_category 「的has_many：用戶」。我試圖將類型設置爲「：引用」是這樣的...Rails的列有 「：引用」 - 混亂

class AddUserCategoryToUsers < ActiveRecord::Migration 
    def change 
    add_column :users, :user_category, :references, :default => 1 
    end 
end

但它似乎沒有奏效：

== CreateUsers: migrating ==================================================== 
-- create_table(:users) 
    -> 0.0114s 
== CreateUsers: migrated (0.0115s) =========================================== 

== CreateUserCategories: migrating =========================================== 
-- create_table(:user_categories) 
    -> 0.0118s 
== CreateUserCategories: migrated (0.0119s) ================================== 

== AddUserCategoryToUsers: migrating ========================================= 
-- add_column(:users, :user_category, :references, {:default=>1}) 
rake aborted! 
An error has occurred, all later migrations canceled: 

Mysql2::Error: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'references DEFAULT 1' at line 1: ALTER TABLE `users` ADD `user_category` references DEFAULT 1 

Tasks: TOP => db:migrate 
(See full trace by running task with --trace)

下面是完整的跟蹤：

-- add_column(:users, :user_category, :references, {:default=>1}) 
rake aborted! 
An error has occurred, all later migrations canceled: 

Mysql2::Error: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'references DEFAULT 1' at line 1: ALTER TABLE `users` ADD `user_category` references DEFAULT 1 
/Users/jakebuob/.rvm/gems/ruby-1.9.3-p286/gems/activerecord-3.2.8/lib/active_record/connection_adapters/abstract_mysql_adapter.rb:245:in `query' 
/Users/jakebuob/.rvm/gems/ruby-1.9.3-p286/gems/activerecord-3.2.8/lib/active_record/connection_adapters/abstract_mysql_adapter.rb:245:in `block in execute' 
/Users/jakebuob/.rvm/gems/ruby-1.9.3-p286/gems/activerecord-3.2.8/lib/active_record/connection_adapters/abstract_adapter.rb:280:in `block in log' 
/Users/jakebuob/.rvm/gems/ruby-1.9.3-p286/gems/activesupport-3.2.8/lib/active_support/notifications/instrumenter.rb:20:in `instrument' 
/Users/jakebuob/.rvm/gems/ruby-1.9.3-p286/gems/activerecord-3.2.8/lib/active_record/connection_adapters/abstract_adapter.rb:275:in `log' 
/Users/jakebuob/.rvm/gems/ruby-1.9.3-p286/gems/activerecord-3.2.8/lib/active_record/connection_adapters/abstract_mysql_adapter.rb:245:in `execute' 
/Users/jakebuob/.rvm/gems/ruby-1.9.3-p286/gems/activerecord-3.2.8/lib/active_record/connection_adapters/mysql2_adapter.rb:211:in `execute' 
/Users/jakebuob/.rvm/gems/ruby-1.9.3-p286/gems/activerecord-3.2.8/lib/active_record/connection_adapters/abstract_mysql_adapter.rb:461:in `add_column' 
/Users/jakebuob/.rvm/gems/ruby-1.9.3-p286/gems/activerecord-3.2.8/lib/active_record/migration.rb:466:in `block in method_missing' 
/Users/jakebuob/.rvm/gems/ruby-1.9.3-p286/gems/activerecord-3.2.8/lib/active_record/migration.rb:438:in `block in say_with_time' 
/Users/jakebuob/.rvm/rubies/ruby-1.9.3-p286/lib/ruby/1.9.1/benchmark.rb:280:in `measure' 
/Users/jakebuob/.rvm/gems/ruby-1.9.3-p286/gems/activerecord-3.2.8/lib/active_record/migration.rb:438:in `say_with_time' 
/Users/jakebuob/.rvm/gems/ruby-1.9.3-p286/gems/activerecord-3.2.8/lib/active_record/migration.rb:458:in `method_missing' 
/Users/jakebuob/Sites/pears/db/migrate/20121114033751_add_user_category_to_users.rb:3:in `change' 
/Users/jakebuob/.rvm/gems/ruby-1.9.3-p286/gems/activerecord-3.2.8/lib/active_record/migration.rb:407:in `block (2 levels) in migrate' 
/Users/jakebuob/.rvm/rubies/ruby-1.9.3-p286/lib/ruby/1.9.1/benchmark.rb:280:in `measure' 
/Users/jakebuob/.rvm/gems/ruby-1.9.3-p286/gems/activerecord-3.2.8/lib/active_record/migration.rb:407:in `block in migrate' 
/Users/jakebuob/.rvm/gems/ruby-1.9.3-p286/gems/activerecord-3.2.8/lib/active_record/connection_adapters/abstract/connection_pool.rb:123:in `with_connection' 
/Users/jakebuob/.rvm/gems/ruby-1.9.3-p286/gems/activerecord-3.2.8/lib/active_record/migration.rb:389:in `migrate' 
/Users/jakebuob/.rvm/gems/ruby-1.9.3-p286/gems/activerecord-3.2.8/lib/active_record/migration.rb:528:in `migrate' 
/Users/jakebuob/.rvm/gems/ruby-1.9.3-p286/gems/activerecord-3.2.8/lib/active_record/migration.rb:720:in `block (2 levels) in migrate' 
/Users/jakebuob/.rvm/gems/ruby-1.9.3-p286/gems/activerecord-3.2.8/lib/active_record/migration.rb:777:in `call' 
/Users/jakebuob/.rvm/gems/ruby-1.9.3-p286/gems/activerecord-3.2.8/lib/active_record/migration.rb:777:in `ddl_transaction' 
/Users/jakebuob/.rvm/gems/ruby-1.9.3-p286/gems/activerecord-3.2.8/lib/active_record/migration.rb:719:in `block in migrate' 
/Users/jakebuob/.rvm/gems/ruby-1.9.3-p286/gems/activerecord-3.2.8/lib/active_record/migration.rb:700:in `each' 
/Users/jakebuob/.rvm/gems/ruby-1.9.3-p286/gems/activerecord-3.2.8/lib/active_record/migration.rb:700:in `migrate' 
/Users/jakebuob/.rvm/gems/ruby-1.9.3-p286/gems/activerecord-3.2.8/lib/active_record/migration.rb:570:in `up' 
/Users/jakebuob/.rvm/gems/ruby-1.9.3-p286/gems/activerecord-3.2.8/lib/active_record/migration.rb:551:in `migrate' 
/Users/jakebuob/.rvm/gems/ruby-1.9.3-p286/gems/activerecord-3.2.8/lib/active_record/railties/databases.rake:153:in `block (2 levels) in <top (required)>' 
/Users/jakebuob/.rvm/gems/[email protected]/gems/rake-0.9.2.2/lib/rake/task.rb:205:in `call' 
/Users/jakebuob/.rvm/gems/[email protected]/gems/rake-0.9.2.2/lib/rake/task.rb:205:in `block in execute' 
/Users/jakebuob/.rvm/gems/[email protected]/gems/rake-0.9.2.2/lib/rake/task.rb:200:in `each' 
/Users/jakebuob/.rvm/gems/[email protected]/gems/rake-0.9.2.2/lib/rake/task.rb:200:in `execute' 
/Users/jakebuob/.rvm/gems/[email protected]/gems/rake-0.9.2.2/lib/rake/task.rb:158:in `block in invoke_with_call_chain' 
/Users/jakebuob/.rvm/rubies/ruby-1.9.3-p286/lib/ruby/1.9.1/monitor.rb:211:in `mon_synchronize' 
/Users/jakebuob/.rvm/gems/[email protected]/gems/rake-0.9.2.2/lib/rake/task.rb:151:in `invoke_with_call_chain' 
/Users/jakebuob/.rvm/gems/[email protected]/gems/rake-0.9.2.2/lib/rake/task.rb:144:in `invoke' 
/Users/jakebuob/.rvm/gems/[email protected]/gems/rake-0.9.2.2/lib/rake/application.rb:116:in `invoke_task' 
/Users/jakebuob/.rvm/gems/[email protected]/gems/rake-0.9.2.2/lib/rake/application.rb:94:in `block (2 levels) in top_level' 
/Users/jakebuob/.rvm/gems/[email protected]/gems/rake-0.9.2.2/lib/rake/application.rb:94:in `each' 
/Users/jakebuob/.rvm/gems/[email protected]/gems/rake-0.9.2.2/lib/rake/application.rb:94:in `block in top_level' 
/Users/jakebuob/.rvm/gems/[email protected]/gems/rake-0.9.2.2/lib/rake/application.rb:133:in `standard_exception_handling' 
/Users/jakebuob/.rvm/gems/[email protected]/gems/rake-0.9.2.2/lib/rake/application.rb:88:in `top_level' 
/Users/jakebuob/.rvm/gems/[email protected]/gems/rake-0.9.2.2/lib/rake/application.rb:66:in `block in run' 
/Users/jakebuob/.rvm/gems/[email protected]/gems/rake-0.9.2.2/lib/rake/application.rb:133:in `standard_exception_handling' 
/Users/jakebuob/.rvm/gems/[email protected]/gems/rake-0.9.2.2/lib/rake/application.rb:63:in `run' 
/Users/jakebuob/.rvm/gems/[email protected]/gems/rake-0.9.2.2/bin/rake:33:in `<top (required)>' 
/Users/jakebuob/.rvm/gems/[email protected]/bin/rake:19:in `load' 
/Users/jakebuob/.rvm/gems/[email protected]/bin/rake:19:in `<main>' 
/Users/jakebuob/.rvm/gems/ruby-1.9.3-p286/bin/ruby_noexec_wrapper:14:in `eval' 
/Users/jakebuob/.rvm/gems/ruby-1.9.3-p286/bin/ruby_noexec_wrapper:14:in `<main>' 
Tasks: TOP => db:migrate

來源

2012-11-14 jake

回答

2

:references類型不存在。你需要創建真正的列。

class AddUserCategoryToUsers < ActiveRecord::Migration 
    def change 
    add_column :users, :user_category_id, :integer, :default => 1 
    end 
end

創建索引也是一個好主意。

class AddUserCategoryToUsers < ActiveRecord::Migration 
    def change 
    add_column :users, :user_category_id, :integer, :default => 1 
    add_index :users, :user_category_id 
    end 
end

的.references方法只存在作爲這一工作表定義（here's an example）

class AddUserCategoryToUsers < ActiveRecord::Migration 
    def change 
    change_table :users do |t| 
     t.references :user_category, :default => 1 
    end 
    end 
end

來源

2012-11-14 15:37:40

+0

（前兩個）的一部分。我不確定爲什麼 - 這是我對Rails的一種典型感受。與其他解決方案相比，其中一種解決方案的優勢是什麼？ – jake

0

「引用」不是列類型。您可以在創建/修改表格時使用引用方法，但所有的Rails都會爲您添加一個整數列。你想要的是添加一個名爲user_category_id的列，輸入integer，然後確保在模型中正確設置關聯。

來源

2012-11-14 15:36:26 MrDanA

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