Rails可选注册-保存前更改参数

Question

I'm developing an application with optional sign up. I want to allow users, with and without accounts, to be able to add links. How could I assign a user's session[user_id] to the user_id column of Link if they're signed in when creating a link?

Current code: user_id remains nil in either case

  def create
    @link = Link.new(params[:link]) 
    if @link.save
      flash[:notice] = "The link was successfully added"
      redirect_to :action => :hot
    else 
      redirect_to :action => :new
    end
  end 

I'm imagining something like this..

  def create
    if session[:user_id]
    #@link equals new link params with user_id = session[:user_id]
    else
    @link = Link.new(params[:link]) 
    end 
    if @link.save
      flash[:notice] = "The link was successfully added"
      redirect_to :action => :hot
    else 
      redirect_to :action => :new
    end
  end 

Answer 1

def create
  @link = Link.new params[:link]
  @link.user_id = session[:user_id] if session[:user_id]
  if @link.save
    redirect_to { action: 'hot' }, notice: 'The link was successfully added'
  else
    render :new
  end
end

The link will be saved with params[:link] even if the user isn't logged-in.

Be cautious to use render, not redirect_to, when a validation fails (see if you want http://guides.rubyonrails.org/action_controller_overview.html )