Saving data from client to server in Ruby?

Question

ruby

Good afternoon!
I ask for advice or, perhaps, even an implementation example, if anyone has one.
The question is quite simple (and probably stupid), but I could not find an answer to it due to the dominance of Rails. No matter how I make a search query, I stumble upon manuals on ActiveRecord and its "friends".
Actually, my question is this: how to transfer data from the client (for example, values ​​from the form filled in by the user) to the server, so that the server already saves the data in the database? Server without Rails but with Ruby.
In simple words: I have form.html with inputs and forms, I have calc.rb with a certain algorithm for calculating the received values ​​and saving them in the database. How can I link these files?
I understand that the question is amateurish, I ask you to forgive me for this.
Thanks in advance for any help.

Answer 1

1. Displaying the form to the client, GET
   1. Installing the minimalistic framework SinatraRb
   2. Gemfile in the root of the project
   

   source 'https://rubygems.org'
   
   gem 'rack'
   gem 'sinatra'
   #gem 'haml'
   #gem 'sqlite3'

   
   and execute the command on the command line
   (gem bundler - gem dependency management - must be installed in advance)
   3. The config.ru file in the root of the project
   

   # config.ru (run with rackup)
   require 'rubygems'
   require 'bundler/setup'
   
   Bundler.require
   
   require './myapp.rb'
   run Sinatra::Application

   
   4. The file myapp.rb in the root of the project
   

   require 'sinatra'
   
   get '/' do
     erb :index # Отобразить форму по пути views/index.erb. Erb - это код HTML с вкраплениями кода на Ruby
   end
   
   post '/do_it'
     "Thank you, #{params['name']}!"
   end

   
   5.views/index.erb
   

   <form action="/do_it" method="post">
       <div>
           <label for="name">Your Name:</label><br>
           <input type="text" name="name"><br>
       </div>
       <button type="submit">Submit</button>
   </form>

   
   Additionally
   Accessing the Request Object
   To work with the DBMS, there is also a simple DataMapper gem