How can I have ActiveRecord's pluck also return the column name for rendering in json?

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def jsontest
   @users = User.all.limit(10)
   render json: @users
end

yields

{
...

"id": 7,
"name": "Sage Smith",
"email": "example-6@railstutorial.org",
"created_at": "2013-10-17T02:29:15.638Z",
"updated_at": "2013-10-17T02:29:15.638Z",
"password_digest": "$2a$10$taHk3udtWN61Il5I18akj.E90AB1TmdL1BkQBKPk/4eZ7YyizGOli",
"remember_token": "118f807d0773873fb5e4cd3b5d98048aef4f6f59",
"admin": false

...
}

But I would like to omit certain certain fields from this API, so I use pluck

def jsontest
  @users = User.all.limit(10).pluck(:id, :name, :email, :created_at) ###
  render json: @users
end

but pluck returns an array of only values, when I would like to have each object's attributes accessible by hash key. 

[
...

    7,
    "Sage Smith",
    "example-6@railstutorial.org",
    "2013-10-17T02:29:15.638Z"

...    

]

So how can I effectively pluck the values and their keys?

I realize I could sweep through @users and grab the keys before plucking and recreate the hash, but I'm expecting there to be some convenience method that does exactly what I want.

activerecord ruby-on-rails
7 Answers

You can pull the data along with the column name as:

@users = User.all.limit(10)
                 .pluck(:id, :name, :email, :created_at)
                 .map {|id, name, email, created_at| { id: id, name: name, 
                                                       email: email, 
                                                       created_at: created_at } }

This will pull the data and map it according to how you want it. One advantage of using pluck over select is that you can use joins along with it.

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