Audited: undefined method `associated' for nil:NilClass

So I have a Entry model with a column called created_by which I would like to default to the first User who created the entry. I installed audited and in my Entry model I have:

belongs_to :user
audited :associated_with => :user

Similarly in my User model I have the following statements:

has_many :entries     
has_associated_audits

In my entries form, I was trying to create a hidden_field in which I was trying to set created_by to be equal to the the associated user of the first audit on the entry. However I'm getting this error, when I try to load the form view:

undefined method `associated' for nil:NilClass

Here is the code in the view:

 .field
   = f.label :created_by
 %br
   = f.hidden_field :created_by, value: @entry.audits.first.associated

And here is the code in the entries_controller where I set @entry in the view:

  def new
    @entry = Entry.new
    authorize! :create, @entry

    @project = Project.find(params[:project_id])
    @entry.project_id = @project.id
    authorize! :update, :read, @project
  end

I realize that, intuitively, it doesn't make much sense to call @entry.audits in the event of creating a new audit, since it has not yet been saved. Should I set the value of @entry.created_by after I call @entry.save in the create method of the controller? Not really sure about what is the most practical approach to take here.

Thanks,

Micha'el.

Solution

What I'd do is remove the created_by hidden field from the form (that is easily intercepted), and instead set from within the controller before the entry is saved using current_user (or alternative) to access the user creating the entry.

def create_entry
  @entry.created_by = current_user
  @entry.save
end

I wouldn't consider it important to assign the created_by user after the audit has been saved via @entry.audits.first.associated because those audits should be associated to the same current_user. If that isn't the case, you have bigger problems on your hands.