Response Object

The response object (res) is used to build the HTTP response.

Properties

res.status_code

Set the HTTP status code:

get "/ok" do |req, res|
  res.status_code = 200
  res
end

get "/not-found" do |req, res|
  res.status_code = 404
  res.body = "Not Found"
  res
end

post "/created" do |req, res|
  res.status_code = 201
  res.body = "Created"
  res
end

Common status codes:

• 200 - OK
• 201 - Created
• 204 - No Content
• 301 - Moved Permanently
• 302 - Found (Redirect)
• 400 - Bad Request
• 401 - Unauthorized
• 403 - Forbidden
• 404 - Not Found
• 500 - Internal Server Error

res.headers

Set response headers as a hash:

get "/" do |req, res|
  res.status_code = 200
  res.headers = {
    "Content-Type" => "text/html",
    "X-Custom-Header" => "value",
    "Cache-Control" => "public, max-age=3600"
  }
  res.body = "<h1>Hello</h1>"
  res
end

res.body

Set the response body as a string:

get "/json" do |req, res|
  res.status_code = 200
  res.headers = { "Content-Type" => "application/json" }
  res.body = JSON.generate({
    message: "Hello",
    timestamp: Time.now.to_i
  })
  res
end

Returning the Response

Always return the res object from the route handler:

get "/example" do |req, res|
  res.status_code = 200
  res.body = "Example"
  res  # Important: return the response object
end