檢查mysql表是否已經存在

Question

我使用activerecord連接mysql數據庫並在連接後創建一個表。 到目前爲止它效果很好，問題是我不知道如何檢查表是否已經存在。我認爲這將適用於table.exist？但不知何故，我沒有... ... 所以這是我走到這一步：

ActiveRecord::Base.establish_connection(
     :adapter => "mysql", 
     :host => "localhost", 
     :username => "my-username", 
     :password => "my-password", 
     :database => "my-db", 
     :encoding => "UTF8" 
    ) 

    # How to check if it exists already? table_name.table.exist? doesnt really work... 
    name = "my_table" 
if name.!table.exist? 
    ActiveRecord::Schema.define do 
     create_table :"#{name}" do |table| 
      table.column :foo, :string 
      table.column :bar, :string 
     end 
    end 
else 
puts "Table exist already..." 
end 
    # Create ActiveRecord object for the mysql table 
    class Table < ActiveRecord::Base 
     set_table_name "#{name}" 
    end 

Answer 1

您需要使用#tables方法的數據庫連接。

unless ActiveRecord::Base.connection.tables.include? name 
    ActiveRecord::Schema.define do 
    create_table :"#{name}" do |table| 
     table.column :foo, :string 
     table.column :bar, :string 
    end 
    end 
end