Why do you have to use fetch for Rails params?

Question

In the docs, they have:

params = ActionController::Parameters.new(person: { name: "Francesco" })

and then use params.fetch(:person) to get person, but can't you just do params[:person]? to get the same data?

Answer 1

I suppose it depends on the behavior you desire.

params = ActionController::Parameters.new
params.fetch(:person)

Will raise an error. As reflected in the docs, you can specify further behavior with fetch, if you so desire.

params = ActionController::Parameters.new
params[:person]

Will return nil.