从哈希数组中获取特定键的值

Question

params = [{id: 1, name: 'hoge'}, {id: 2, name: 'fuga'}]

I know I can fetch the values of a specific key in this way.

params.map{ |u| u.name }
=> ["hoge", "fuga"]

But, I wanna do this without block like below,

params.map(&:name)

If the params is ActiveRecord, I can do in above way. Even if params is a hash, please tell me if anyone knows how to do this?

Answer 1

Given

params = [{id: 1, name: 'hoge'}, {id: 2, name: 'fuga'}]

As emaillenin says, you can do:

params.map { |p| OpenStruct.new(p) }.map(&:name)

But, if you do:

params.map { |p| OpenStruct.new(p).name }

You save an iteration and seven key strokes. And if you do:

params.map { |p| p[:name] }

You save an additional 14 characters. But, you can't do:

params.map{ |u| u.name }

If u is a Hash . Nor can you do:

params.map(&:name)

Answer 2

If you are using rails, and not vanilla ruby, what you're really looking for is pluck !

params = [{id: 1, name: 'hoge'}, {id: 2, name: 'fuga'}]
params.pluck(:name)

=> ["hoge", "fuga"]

https://apidock.com/rails/ActiveRecord/Calculations/pluck

Answer 3

params = [{id: 1, name: 'hoge'}, {id: 2, name: 'fuga'}]
params.map { |p| OpenStruct.new(p) }.map(&:name)

# ["hoge", "fuga"]