💌 params[]: Direct from the user

  • Comes from the request itself: URL segments (:id), query strings (?foo=bar), or form data.
  • You use it in the same route where the request is made.
  • It's like checking the envelope of a letter to see who it's from. It's raw input.

Example:

params[:id] # from `/blog/42`
params[:search] # from `/search?search=cats`

💅 @instance_variable: For sharing across templates

  • Used to pass data to views (templates), or between routes if you're being fancy.
  • You set it in the route/controller action and access it in the view (erb, haml, whatever).
  • It’s like putting your lipstick on the table for others to use. You're saying, "Here, this is for the next part."

Example:

@article = fetch_api(...)
# later in the view: <%= @article['title'] %>

💡 Rule of Thumb

  • Use params[] to get data from the request.
  • Use @variables to send data to the view or carry stuff along in your code.
  • Always guard against nil when dealing with external data. They're like unreliable exes — might show up, might ghost you.

If you ever get confused again, just ask yourself:

“Is this coming from the outside world? Or is this something I already put on the shelf for later?”