Rails: undefined method `any?' for nil:NilClass - ruby-on-rails

Question

I'm getting these params in the console:
category_id" # => ["", "14", "16", "17"]
When I check if the array is empty or not inside a model with this:
#category = category_id.any?
it returns the following error:
undefined method `any?' for nil:NilClass
I have the strong params like this:
:category_id => []
Any ideas on how to check if this array is empty or not?
def new
#account = Account.new
#categories.build
end
def create
#account = Account.new(account_params)
respond_to do |format|
if #account.save
format.html { redirect_to accounts_path, notice: 'Account was successfully added.' }
format.json { render :index, status: :created, location: #account }
else
format.html { render :new }
format.json { render json: #account.errors, status: :unprocessable_entity }
end
end
end
def account_params
params.require(:account).permit(:name, :street, :street_2, :city, :state, :postal_code, :country, category_id: []
end
console results:
"account"=>{"name"=>"", "street"=>"", "street_2"=>"", "city"=>"", "state"=>"", "postal_code"=>"", "country"=>"", "category_id"=>["", "14", "15"]

Answer 1

#variables are not available inside the model. Neither are the params.
It's good practice to not try to do so but here are some ways to do it:
If you want to pass a value that is a database field/column:
# In the controller
account = Account.new(:category => #category)
# In this example, :category is a database field/column of the
# Account model, not sure if that's accurate for you.
If not then you gotta use an attr_accessor like this:
# In the model
class Account < ActiveRecord::Base
attr_accessor :category
#In the controller (this is equivalent to the first example)
account = Account.new
account.category = #category
Using attr_accessor doesn't save anything into the database, but the controller doesn't know the difference (which is good). This allows you to move data around like you wanted.