ruby-on-rails - Rails 3.2 迁移无法在更改方法中向 create_table 添加索引

Question

这是我在 Rails 3.2.2 中的迁移:

class CreateStatistics < ActiveRecord::Migration
  def change
    create_table :statistics do |t|
      t.string :name
      t.integer :item_id
      t.integer :value
      t.text :desc

      t.timestamps
      t.index [:name, :item_id]
    end

  end
end

这是迁移错误:

==  CreateStatistics: migrating ===============================================
-- create_table(:statistics)
ActiveRecord::ConnectionAdapters::TableDefinition
rake aborted!
An error has occurred, all later migrations canceled:

undefined method `index' for #<ActiveRecord::ConnectionAdapters::TableDefinition:0xbd16888>

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

创建索引的正确方法是什么？

Answer 1

您仍然可以添加索引作为“更改”迁移的一部分。您只需在 create_table 调用之外执行此操作即可:

class CreateStatistics < ActiveRecord::Migration
  def change
    create_table :statistics do |t|
      t.string :name
      t.integer :item_id
      t.integer :value
      t.text :desc

      t.timestamps
    end

    add_index :statistics, [:name, :item_id]
  end
end

这会在“向上”迁移时正确创建表和索引，并在“向下”迁移时删除索引和表。