我正在尝试创建“所有者与财产之间的一对多关系”，但我不知道为什么会出现此错误，在生成模型后，我尝试在运行rake db:migrate之前添加_index ，但出现了问题注意：这是第一次使用 ruby on rails 创建两个表之间的关系，我在 rubyonrails guide 中搜索了我没有找到答案
我的迁移文件：
class CreateProperties < ActiveRecord::Migration
def change
create_table :properties do |t|
t.string :p_street
t.string :p_city
t.string :postcode
t.string :type
t.integer :rooms
t.integer :rent
t.integer :owner_id
t.timestamps
end
add_index :owner_id
end
end
出现的错误：
== CreateProperties: migrating ===============================================
-- create_table(:properties)
-> 0.0712s
-- add_index(:owner_id)
rake aborted!
An error has occurred, this and all later migrations canceled:
wrong number of arguments (1 for 2)/var/lib/gems/1.9.2/gems/activerecord-3.2.13/lib/active_record/connection_adapters/abstract/schema_statements.rb:350:in `add_ind
ex'
/var/lib/gems/1.9.2/gems/activerecord-3.2.13/lib/active_record/migration.rb:466:in `block in method_missing'
/var/lib/gems/1.9.2/gems/activerecord-3.2.13/lib/active_record/migration.rb:438:in `block in say_with_time'
/var/lib/gems/1.9.2/gems/activerecord-3.2.13/lib/active_record/migration.rb:438:in `say_with_time'
/var/lib/gems/1.9.2/gems/activerecord-3.2.13/lib/active_record/migration.rb:458:in `method_missing'
/root/rails_project/dream_home/db/migrate/20130503044654_create_properties.rb:14:in `change'
/var/lib/gems/1.9.2/gems/activerecord-3.2.13/lib/active_record/migration.rb:407:in `block (2 levels) in migrate'
/var/lib/gems/1.9.2/gems/activerecord-3.2.13/lib/active_record/migration.rb:407:in `block in migrate'
/var/lib/gems/1.9.2/gems/activerecord-3.2.13/lib/active_record/connection_adapters/abstract/connection_pool.rb:129:in `with_connection'
/var/lib/gems/1.9.2/gems/activerecord-3.2.13/lib/active_record/migration.rb:389:in `migrate'
/var/lib/gems/1.9.2/gems/activerecord-3.2.13/lib/active_record/migration.rb:528:in `migrate'
/var/lib/gems/1.9.2/gems/activerecord-3.2.13/lib/active_record/migration.rb:720:in `block (2 levels) in migrate'
/var/lib/gems/1.9.2/gems/activerecord-3.2.13/lib/active_record/migration.rb:775:in `call'
/var/lib/gems/1.9.2/gems/activerecord-3.2.13/lib/active_record/migration.rb:775:in `block in ddl_transaction'
/var/lib/gems/1.9.2/gems/activerecord-3.2.13/lib/active_record/connection_adapters/abstract/database_statements.rb:192:in `transaction'
/var/lib/gems/1.9.2/gems/activerecord-3.2.13/lib/active_record/transactions.rb:208:in `transaction'
/var/lib/gems/1.9.2/gems/activerecord-3.2.13/lib/active_record/migration.rb:775:in `ddl_transaction'
/var/lib/gems/1.9.2/gems/activerecord-3.2.13/lib/active_record/migration.rb:719:in `block in migrate'
/var/lib/gems/1.9.2/gems/activerecord-3.2.13/lib/active_record/migration.rb:700:in `each'
/var/lib/gems/1.9.2/gems/activerecord-3.2.13/lib/active_record/migration.rb:700:in `migrate'
/var/lib/gems/1.9.2/gems/activerecord-3.2.13/lib/active_record/migration.rb:570:in `up'
/var/lib/gems/1.9.2/gems/activerecord-3.2.13/lib/active_record/migration.rb:551:in `migrate'
/var/lib/gems/1.9.2/gems/activerecord-3.2.13/lib/active_record/railties/databases.rake:193:in `block (2 levels) in <top (required)>'
/var/lib/gems/1.9.2/gems/rake-10.0.4/lib/rake/task.rb:246:in `call'
/var/lib/gems/1.9.2/gems/rake-10.0.4/lib/rake/task.rb:246:in `block in execute'
/var/lib/gems/1.9.2/gems/rake-10.0.4/lib/rake/task.rb:241:in `each'
/var/lib/gems/1.9.2/gems/rake-10.0.4/lib/rake/task.rb:241:in `execute'
/var/lib/gems/1.9.2/gems/rake-10.0.4/lib/rake/task.rb:184:in `block in invoke_with_call_chain'
/var/lib/gems/1.9.2/gems/rake-10.0.4/lib/rake/task.rb:177:in `invoke_with_call_chain'
/var/lib/gems/1.9.2/gems/rake-10.0.4/lib/rake/task.rb:170:in `invoke'
/var/lib/gems/1.9.2/gems/rake-10.0.4/lib/rake/application.rb:143:in `invoke_task'
/var/lib/gems/1.9.2/gems/rake-10.0.4/lib/rake/application.rb:101:in `block (2 levels) in top_level'
/var/lib/gems/1.9.2/gems/rake-10.0.4/lib/rake/application.rb:101:in `each'
/var/lib/gems/1.9.2/gems/rake-10.0.4/lib/rake/application.rb:101:in `block in top_level'
/var/lib/gems/1.9.2/gems/rake-10.0.4/lib/rake/application.rb:110:in `run_with_threads'
/var/lib/gems/1.9.2/gems/rake-10.0.4/lib/rake/application.rb:95:in `top_level'
/var/lib/gems/1.9.2/gems/rake-10.0.4/lib/rake/application.rb:73:in `block in run'
/var/lib/gems/1.9.2/gems/rake-10.0.4/lib/rake/application.rb:160:in `standard_exception_handling'
/var/lib/gems/1.9.2/gems/rake-10.0.4/lib/rake/application.rb:70:in `run'
Tasks: TOP => db:migrate
(See full trace by running task with --trace)