rake route - No route matches [GET] "/" Error - ruby-on-rails

Question

On visiting localhost:3000 I'm getting the typical:
No route matches [GET] "/"
I don't want to see that error screen. I already trying with localhost:3000/passbook/v1/passes/ but still nothing so I typed:
rake routes
and got this output:
passbook GET /passbook/v1/passes/:pass_type_identifier/:serial_number(.:format) passbook/passes#show {:pass_type_identifier=>/([\w\d]\.?)+/}
GET /passbook/v1/devices/:device_library_identifier/registrations/:pass_type_identifier(.:format) passbook/registrations#index {:pass_type_identifier=>/([\w\d]\.?)+/}
POST /passbook/v1/devices/:device_library_identifier/registrations/:pass_type_identifier/:serial_number(.:format) passbook/registrations#create {:pass_type_identifier=>/([\w\d]\.?)+/}
DELETE /passbook/v1/devices/:device_library_identifier/registrations/:pass_type_identifier/:serial_number(.:format) passbook/registrations#destroy {:pass_type_identifier=>/([\w\d]\.?)+/}
passbook_log POST /passbook/v1/log(.:format) passbook/logs#create
How can I resolve this?

Answer 1

You haven't told Rails yet what your root path is. You can do this by saying
root to: "passes#show"
in config/routes.rb. Afterwards, you should see this in the rake routes output:
root / passes#show
Then it should work!
Additional tip
This may be over the top for your question, but following the test driven approach you should write a spec first:
describe "custom routing" do
it "shows the root page" do
get("/").should route_to("passes#show")
end
end
Use RSpec for this. Run the test in your console before having written the route itself by doing $ rspec and see the test fail at the right place.
Then, implement the routes above, run the test again—it should work. This way you ensure that you have written just enough code to meet your requirements, and that it is really the code you have written that lets you access the root path.

Answer 2

Is this a rails app you inherited from someone else?
Given the rake routes output you have provided, a url like localhost:3000/passbook/v1/passes/<EXAMPLE_PASS_TYPE_IDENTIFIER>/<EXAMPLE_SERIAL_NUMBER> should work based on the rule in the first line of the output, provided you replace EXAMPLE_PASS_TYPE_IDENTIFIER and EXAMPLE_SERIAL_NUMBER with valid values from the database.
The error message No route matches [GET] "/ for localhost:3000 is because there is no mapping for root in rake routes output.
You could modify the config/routes.rb file and add the following line at the bottom of the file:
root :to => "<controller_name>#<action_name>"
Eg:
root :to => "passbook/index"
if there is a passbooks_contoller.rb with a index method.
Best to learn more about rails routing from the documentation. Even better go through the Rails Tutorial to get a good understanding of the rails framework.