Rails db：migrate用「未定義的局部變量或方法」限制「中止」爲什麼？

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對不起，我的英文。我搜索了該網站，但我找不到解決方案。當我試圖讓軌道分貝：遷移給了我這個錯誤：Rails db：migrate用「未定義的局部變量或方法」限制「中止」爲什麼？

C:\PW\Sites\grota>rails db:migrate 
== 20170209014957 CreateWholesalers: migrating  ================================ 
-- create_table(:wholesalers) 
-- limit() 
rails aborted! 
StandardError: An error has occurred, all later migrations canceled: 

undefined local variable or method `limit' for # <CreateWholesalers:0x00000006bfc6a0> 
C:/PW/Sites/grota/db/migrate/20170209014957_create_wholesalers.rb:7:in  `block in change' 
C:/PW/Sites/grota/db/migrate/20170209014957_create_wholesalers.rb:3:in  `change' 
bin/rails:4:in `require' 
bin/rails:4:in `<main>' 
NameError: undefined local variable or method `limit' for # <CreateWholesalers:0x00000006bfc6a0> 
C:/PW/Sites/grota/db/migrate/20170209014957_create_wholesalers.rb:7:in  `block in change' 
C:/PW/Sites/grota/db/migrate/20170209014957_create_wholesalers.rb:3:in  `change' 
bin/rails:4:in `require' 
bin/rails:4:in `<main>' 
Tasks: TOP => db:migrate 
(See full trace by running task with --trace)

這裏是我的代碼遷移：

class CreateWholesalers < ActiveRecord::Migration[5.0] 
    def change 
    create_table :wholesalers do |t| 
     t.string "brand_name", :limit => 25 
     t.string "username", :limit => 25 
     t.string "password_digest" 
     t.string "email", limit => 50 
     t.decimal "latitude" 
     t.decimal "longitude" 
     t.timestamps 
    end 
    end 
end

預先感謝您。

來源

2017-02-09 Cristiano Morais