Rails Client-Server communication
Published: 2023-09-11 02:51:24

In the world of web development, React and Ruby on Rails have emerged as a popular combination in many tech stacks, powering some of the most popular applications we use daily, like Airbnb and Hulu. Behind the scenes, these applications rely on a process known as the request-response cycle to communicate between the front end (React) and back end (Ruby on Rails). This cycle is the backbone of their functionality, allowing users to seamlessly interact with the platform. In this blog post, I'll break down each step needed to create a RESTful API while exploring the intricacies of client-server communication.


### Understanding the Client-Server Communication:


Before explaining the request-response cycle, let's briefly describe what client-server communication is. In a React and Ruby on Rails application, React acts as the client, running in the user's browser, while Ruby on Rails serves as the server, handling requests from the client and delivering responses.


# Client-Server Communication Steps:


### Step 1: Client Sends a Request


First, a user interacts with the React UI. For instance, a user might want to view a list of available Airbnb properties. The React application sends an HTTP request to the Ruby on Rails server, specifying the type of request (GET, POST, PUT, DELETE) and the resource it needs. Each type of request (also known as HTTP verbs) is associated with a different action. A few common requests:


* GET: Retrieve an item or items 
* POST: Create a new item
* PUT: Update an item 
* DELETE: Delete an item


```javascript
// Fetch listings from the Rails API
// The default request is a GET request 


fetch('/listings')


```


### Step 2. Rails receives the request: 


The request is then processed by the routes file and directed to the appropriate controller action:


```ruby 
# config/routes.rb
Rails.application.routes.draw do
  resources :listings
end


```
In this example, the `resources` method generates a set of RESTful routes for a ListingsController. These routes include actions which correspond to the HTTP verbs:
* index -> GET
* create -> POST
* update -> PUT
* destroy-> DELETE
 


### Step 3: Controller Actions
Once the route is determined, the corresponding controller action is invoked. This action processes the request, interacts with the database if necessary, and prepares a response. Here's a simplified example:


```ruby
# app/controllers/listings_controller.rb
class ListingsController < ApplicationController
  def index
    render json: Listing.all 
  end
end
```
In this snippet, the index action retrieves a list of listings from the database and responds with a JSON representation of these listings.


### Step 4: React Response from the API
On the client side, React sends an HTTP request to the Ruby on Rails API endpoint. This request is handled using the built-in fetch API to make asynchronous requests. Once the request has been processed on the backend, a response is sent to the front end. Shown below:


```javascript


fetch('/listings')
  .then(response => response.json())
  .then(data => {
    setListings(data)
  })
  .catch(error => {
    setError(error)
  });
return (
<ListingsComponent listings={listings} />
)
```


In this snippet, the second `.then` will handle the process of setting the response data, which will then be sent to our React component.


### Step 5: Rendering in React
Once React receives the data from the API, it will be rendered in the user interface. React's virtual DOM efficiently updates only the parts of the UI that need to change, ensuring a smooth and responsive user experience. Here's a simplified example:


```jsx 
// Render listings in a React component
function ListingComponent ({listings}) {
    return (
      <div>
        {listings.map(listing => (
          <div key={listing.id}>
            {listing.title}
          </div>
        ))}
      </div>
    );
export default ListingComponent;
}
``` 
In this snippet, we render a list of listings in a React component based on the data received from the Rails API.


### Network Errors:
While this request-response cycle may seem straightforward, it's important to acknowledge potential network errors. Common errors include:


1. Timeouts: If the server takes too long to respond, the client might time out the request.


2. 404 Not Found: This error occurs when the requested resource is not available on the server, often due to a mistyped URL.


3. 500 Internal Server Error: An error on the server side can result in this status code, indicating that something went wrong while processing the request.


4. Network Connection Issues: Problems like loss of internet connectivity can interrupt the request-response cycle.


Handling these errors gracefully in your application is crucial for providing a seamless user experience. Techniques like error handling, retries, and user-friendly error messages can mitigate the impact of these issues.


In conclusion, the request-response cycle in React and Ruby on Rails is the backbone of many modern web applications. Understanding how the back end and front end work together through this cycle is essential for building robust and responsive web experiences. So, roll up your sleeves, dive into the code, and start building your own incredible web applications!

### Helpful Documentation


[Create-React-App](https://create-react-app.dev/)

[React Fetch](https://developer.mozilla.org/en-US/docs/Web/API/Fetch_API/Using_Fetch)

[Ruby on Rails](https://guides.rubyonrails.org/)

[Routing on Rails](https://guides.rubyonrails.org/routing.html#resource-routing-the-rails-default)

[Rails CLI](https://guides.rubyonrails.org/command_line.html)