CODEWITHSUNDEEP
ruby-on-railsruby-on-rails-4strong-parameters
Misha Moroshko
Misha Moroshko

Reputation: 171341

How to require an Array in Rails when using strong parameters?

Is there a way to require an array when using strong parameters in Rails 4?

> params = ActionController::Parameters.new(contacts: [])
 => {"contacts"=>[]} 
> params.require(:contacts)
ActionController::ParameterMissing: param not found: contacts

Upvotes: 2

Views: 4003

Answers (3)

flash
flash

Reputation: 1

Have you tried this

params.permit(contacts: []).require(:contacts)

Upvotes: 0

johncip
johncip

Reputation: 2259

As Steve Wilhelm noted, it works if the array is non-empty. It only fails on your example because the contacts array is empty. But that's usually the desired behavior.

If you don't care what's in the array, just use permit.

That said, I'd imagine the most common case is that you want an array of hashes with known keys. I would do that this way:

# Returns an array of contacts after checking the params shape
# Use instead of params[:contacts]
def contacts_params
  params.permit(contacts: %i(id name phone address))
  params.require(:contacts)
end

Upvotes: 4

Steve Wilhelm
Steve Wilhelm

Reputation: 6260

It appears you can have arrays of Scalars, This works

> params = ActionController::Parameters.new(contacts: [nil])
=> {"contacts"=>[nil]}
> params.require(:contacts)
=> [nil]
> params = ActionController::Parameters.new(contacts: [1])
=> {"contacts"=>[1]}
> params.require(:contacts)
=> [1]

Here is the description from documentation

The permitted scalar types are String, Symbol, NilClass, Numeric, TrueClass, FalseClass, Date, Time, DateTime, StringIO, IO, ActionDispatch::Http::UploadedFile and Rack::Test::UploadedFile.

To declare that the value in params must be an array of permitted scalar values map the key to an empty array:

params.permit(id: [])

Upvotes: 0

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