Ruby on Rails的：是否有以从数据库中检索数据的阵列，而不需要Rails的实例什么方法？ [英] Ruby on Rails: Is there a method to retrieve an array of data from the database without Rails needing to instantiate anything?

问题描述

我有一个模型，我尝试从数据数组，而我不需要对数据进行实例化到Ruby对象。其实，这只是引入了一个额外的步骤到我的code单步执行对象，并生成一个新的数组，正是我所需要的数据。

I have a model that I'm trying to retrieve an array of data from, and I don't need the data to be instantiated into Ruby objects. In fact, that just introduces an extra step into my code to step through the objects and generate a new array with just the data I need.

例如：

class Book
  #has attribute in database title
end

我想生成包含所有图书数据库的所有标题的数组。什么是做到这一点的最好方法是什么？

I would like to generate an array which contains all the titles of all the Books in the database. What's the best way to do it?

推荐答案

ActiveRecord的给你一个直接的挂钩，以目前的环境数据库，让您执行SQL语句并返回结果的基本结构（数组或哈希）。参见：<一href="http://ar.rubyonrails.org/classes/ActiveRecord/ConnectionAdapters/DatabaseStatements.html">http://ar.rubyonrails.org/classes/ActiveRecord/ConnectionAdapters/DatabaseStatements.html

ActiveRecord gives you a direct hook to the current environment database, allowing you execute SQL statements and returning the result in basic structures (arrays or hashes). See: http://ar.rubyonrails.org/classes/ActiveRecord/ConnectionAdapters/DatabaseStatements.html

例如：

ActiveRecord::Base.connection.select_values("SELECT title FROM books")

将返回书名（字符串）数组。这不会实例化任何ActiveRecord的实例，并且将更多的内存高效的为您的应用程序。

Will return an array of book titles (strings). This will not instantiate any ActiveRecord instances and will be more memory efficient for your application.

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