Ruby:将一组 ActiveRecord 对象分组到一个散列中 [英] Ruby: group an array of ActiveRecord objects in a hash

问题描述

我想将 ActiveRecord 对象数组分组到一个散列中，该散列具有易于在 SQL 语句后查询的接口，如下所示:

I'd like to group an array of ActiveRecord objects into a hash with an interface that's simple to query after an SQL statement that looks like the following:

SELECT name,value from foo where name IN ('bar', 'other_bar') LIMIT 2;

在那个查询之后，我想要一个我可以去的哈希:

After that query, I want a hash where I can go:

foo[:bar] # output: value1
foo[:other_bar] # output: value2

使用 ActiveRecord 收集对象并将它们分组以便我可以使用上面的界面的最佳方法是什么?

What's the best way to collect the objects with ActiveRecord and group them so I can use the interface above?

推荐答案

In Rails 2

foos = Foo.all :select => "name, value",
               :conditions => ["name in (?)", %w(bar other_bar)],
               :limit => 2

在 Rails 3 中

In Rails 3

foos = Foo.where("name in (?)", %w(bar other_bar)).select("name, value").limit(2)

然后

foo = Hash[foos.map { |f| [f.name.to_sym, f.value] }]

或

foo = foos.inject({}) { |h, f| h[f.name.to_sym] = f.value; h }

或在 Ruby 1.9 中

or in Ruby 1.9

foo = foos.each_with_object({}) { |f, hash| hash[f.name.to_sym] = f.value }

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