Method Return Value, Displayed in the Browser

The code below defines a Sinatra route and includes a method initially written to print a shape at the command line.

The method was modified so the return value was displayed in the browser instead.

The comments make it a bit harder to read, but hopefully the intent remains relatively clear.

Also, if you're not familiar with until loops, they basically run until the initial condition you set, is met.

In this case, until the variable counter is equal to height + 1 (in the example below,5), do the following stuff.

require 'sinatra'

def show_params
  p params
end

get("/home") do
  erb(:home)
end

get("/pyramid") do
  # Use a form to make a GET request to "/pyramid"

  # debugging/learning method, shows contents of params hash
  show_params()

  def print_horizontal_pyramid(height)
    counter = height / height

    # print counter to terminal
    p counter

    # print a new line in terminal
    puts "\n"

    # new var set to empty array
    pyramid_array = []

    # until loop, until counter is equal to height + 1 (e.g. 5), do the next line
    until counter == height + 1

      pyramid_array.push("<h3>" + " " * ( height - counter ) + "*" * ( (counter)+(counter) ) + "</h3>" )

      # check the terminal to see what the array looks like each time the loop happens.
      p pyramid_array

      # add one to the counter
      counter += 1

      # print out each iteration of the counter
      p counter
    end

    # return the result of the final iteration
    pyramid_array
  end
  # takes in the param height, string form, and converts to an integer
  height = params[:height].to_i

  # runs the method we defined above
  print_horizontal_pyramid(height)

end

Here's what the terminal output looks like.

Here is the associated form that can be added to the home.erb page.

I used forms for the input instead of having to manually add the parameters via the address bar.

<form method="GET" action="/pyramid">
  <input type="text" name="height" placeholder="Number of stars">
  <input type="submit" value="submit">
</form>

Parameters are passed from the client (browser) to the server as a hash, a key | value pair.

Hashes passed between the client and server often look like this.

{"height"=>"4"}

In the form above, the name field will set the key, "height" in the param hash. The value corresponds the number we choose to enter when filling out the form, in this case, "4".

The reason this works, why the stars are rendered in the browser, is because of Rack and Sinatra. See ~ line 128 in Sinatra/base.rb for the specifics.

You can return any object that would either be a valid Rack response, Rack body object or HTTP status code: * An Array with three elements: [status (Fixnum), headers (Hash), response body (responds to #each)] * An Array with two elements: [status (Fixnum), response body (responds to #each)] * An object that responds to #each and passes nothing but strings to the given block * A Fixnum representing the status code

Since the object we're returning, an array, responds to .each, it is passed and rendered.

This post assumes an application directory structure that resembles:

If you attempt to mirror or use this code and have a problem, reach out to [email protected]