Redirect and render in Ruby on Rails - Step-by-Step Execution

Concept Flow - Redirect and render

Controller action starts

↓

Decision: Redirect or Render?

Redirect→Send HTTP redirect response

↓

Browser requests new URL

↓

Render view template

↓

New controller action runs

↓

Send HTTP response with HTML

↓

Request ends

The controller decides to either redirect the browser to a new URL or render a view template directly, sending the appropriate HTTP response.

Execution Sample

Ruby on Rails

def show
  if user_signed_in?
    redirect_to dashboard_path
  else
    render :login
  end
end

This controller action redirects signed-in users to the dashboard, otherwise renders the login page.

Execution Table

Step	Condition	Result	Action Taken	Response Sent
1	user_signed_in? == true	True	redirect_to dashboard_path	HTTP 302 Redirect to /dashboard
2	N/A	N/A	Browser requests /dashboard	New request starts
3	N/A	N/A	New controller action runs	Depends on new action
4	user_signed_in? == false	False	render :login	HTTP 200 OK with login HTML

💡 Execution stops after sending either redirect or render response.

Variable Tracker

Variable	Start	After Step 1	After Step 4	Final
user_signed_in?	unknown	true or false	false if render branch	final boolean value

Key Moments - 2 Insights

Why does redirect_to cause a new request instead of rendering a view?

redirect_to sends an HTTP 302 response telling the browser to load a new URL, so the current request ends and a new one begins (see execution_table steps 1 and 2).

Can you call render and redirect_to in the same controller action?

No, calling redirect_to or render ends the response immediately. The code after them won't run (see execution_table where only one action sends a response).

Visual Quiz - 3 Questions

Look at the execution table, what response is sent when user_signed_in? is true?

A No response sent

B HTTP 200 OK with login HTML

C HTTP 302 Redirect to /dashboard

D HTTP 404 Not Found

💡 Hint

Check step 1 in the execution_table where user_signed_in? is true.

At which step does the browser make a new request after redirect?

A Step 1

B Step 2

C Step 3

D Step 4

💡 Hint

Look at execution_table step 2 describing the browser requesting the new URL.

If user_signed_in? is false, what action does the controller take?

A Render the login template

B Raise an error

C Redirect to dashboard_path

D Do nothing

💡 Hint

See execution_table step 4 where render :login is called.

Concept Snapshot

redirect_to sends an HTTP redirect response causing the browser to request a new URL.
render sends an HTTP response with a view template without a new request.
Only one of redirect_to or render should be called per controller action.
redirect_to ends the current request; render displays a view immediately.
Use redirect_to for navigation, render for showing views in the same request.

Full Transcript

In Rails controllers, you can either redirect or render in an action. Redirect sends a 302 HTTP response telling the browser to load a new URL, which starts a new request cycle. Render sends an HTML response directly without a new request. The controller decides based on conditions like user login status. Only one of redirect_to or render should be called per action because both end the response. Redirect causes the browser to make a new request, while render shows a view immediately. This flow helps control user navigation and page display in web apps.