CODEWITHSUNDEEP
ruby-on-rails-4rails-activerecord
George Armhold
George Armhold

Reputation: 31064

Rails 4: query by id, but only include specified columns in the resulting model

So in Rails 3.x I used to be able to say:

id = 123
book = Book.find(id, select: ['title', 'description'])

and get back a Book that had only those fields that I specified. This was really handy as it allowed me to exclude certain large columns from my queries, yet still get back working ActiveRecord entities. Especially useful in a heavily de-normalized DB situation.

Now in Rails 4 this comes with a warning:

[WARN] DEPRECATION WARNING: Passing options to #find is deprecated. 
Please build a scope and then call #find on it.

I can't quite seem to figure out the syntax for specifying column selection for a scope, so I end up with:

scope :my_find_by_id, -> id { where(id: id)}

and then calling it like:

Book.my_find_by_id(id).select(['title', 'description']).first

which seems rather verbose and silly. Is there a more idiomatic way to acomplish this in Rails 4?

Upvotes: 0

Views: 1326

Answers (2)

Xuwen
Xuwen

Reputation: 231

Just call the select method before find:

Book.select(:title, :description).find(id)

Upvotes: 1

Thanh
Thanh

Reputation: 8604

You can use select method to get title and description:

With scope:

scope :my_find_by_id, ->(id) { where(id: id).first }

Book.my_find_by_id(id).select(:title, :description)

Upvotes: 0

Related Questions