Introduction to Build a Modern Angular Application with Signals

Course Introduction

Project Architecture Build a Modern Angular Application with Signals

Project Architecture

This module initiates your journey by highlighting the significance of lightweight dependencies, improved reactivity, and optimized performance in application development using Angular 17. Understand the reasons driving the upgrade from previous Angular versions to Angular 17.

Introduction

Getting started with the concept of signals

The Concept of Signals

The importance of Signals over Change Detection and Zone.js

In this lesson, you will learn how to create our first Signals variable in Angular. You get to see how easy it is to declare variables compared to doing it with Observables which has a more robust boilerplate code.

How to Create a Signal

Here, you will get to learn about the different Reactive primitives available in Signals, which are writable signals, computed and effects.

Reactive Primitives in Signals

Discover the foundational concept of Signals within Angular and its relevance in the ecosystem. Understand the pivotal role Signals play, addressing performance concerns and simplifying Angular application development.

 Getting Started with Signals

This video provides an insight into what we are going to do in this module.

Module 3 Introduction

In this module, you’ll learn how to combine RxJS and Signals when working with HTTP requests from the REST API. We will learn how to work with the Interoperability API when dealing with asynchronous operations in Signals.

Fetching Data from the Server using RxJS

Here we get to modify the code we wrote previously to fetch data from the server. We go ahead to show the simplicity of Signals by converting the data gotten from the Observable into Signals making use of the Interoperability API.

Using the Interoperability API to convert Http requests to Signals

Combine RxJS and Signals to navigate HTTP requests from REST APIs. Learn to leverage the Interoperability API for managing asynchronous operations within Signals.

Signals and Http Requests

Module 4 Introduction

In this module, we get to display how to spread data across different components with the use of Signals.

Adding Items to the Shopping Cart

In this module, we will utilise Signals to increase and decrease the number of items to add to cart =, as well as integrate functionality to remove an item from cart.

Integrate Counter Functionality and Remove Items from Cart

In this lesson, we get a summary of all the items that have been added to the cart, which includes the number of items bought and the cart total.

Implement the Checkout Page

Exercise

In this lesson, we will take a look at how to handle errors in Signals.

Error Handling in Signals

Explore the techniques of disseminating data across various components using Signals, facilitating efficient communication and data exchange.

Sharing Data Between Different Components with Signals

We will do a review of all the concepts learned in the course and also look at the upcoming features to be integrated into Signals.

Wrapping up the Course

In the final module, we comprehensively review every concept that's been covered in this course. Additionally, this module provides insights into upcoming features to be integrated into Angular 17 Signals.

Course Wrap Up

### How The Course Works:

- The "Build a Modern Web Application using Angular Signals" course is a comprehensive online program spanning five modules. Discover how to effectively utilize Signals to manage the entire state of an Angular application, integrate the newly built-in control flows, employ deferrable views, navigate components using lazy loaded routes, and implement Standalone components.
- Remote Access: Take advantage of the course from any location, allowing you the flexibility to engage with the materials at your convenience.
- Self-Paced Learning: Tailor your learning experience to your schedule, enabling you to progress through the course content at your own pace.
- Community Engagement: Collaborate and learn alongside a diverse community of fellow students, fostering an environment of shared knowledge and support.
- Structured Learning: Experience a well-organized curriculum designed to provide a cohesive and comprehensive understanding of Angular Signals in a logical progression.

### Understanding the Challenges

Learning Angular 17 can present various hurdles and frustrations for those new to the technology. As individuals navigate their journey into this advanced framework, they commonly encounter several challenges:

- Complexity Barrier: The intricate architecture and extensive feature set of Angular 17 can overwhelm newcomers, posing a significant learning curve.
- State Management Complexity: Managing the state of an Angular application efficiently, especially with the nuances of Signals, can prove challenging for learners.
- Integration Puzzles: Integrating and harnessing newly built-in control flows, deferrable views, Standalone components, and lazy loaded routes can be intricate and perplexing.
- Navigational Complexity: Understanding the intricacies of lazy loaded routes and effective navigation between components can pose obstacles to a smooth learning experience.

Navigating through these complexities without guidance can hinder the progress of aspiring developers aiming to master Angular 17.


### Advantages of Learning Angular 17 in 2023

- Enhanced Performance: In 2023, Angular 17 offers optimized performance enhancements, enabling you to craft high-performing web applications capable of meeting modern user expectations.
- Cutting-Edge Features: Stay ahead in the web development landscape by mastering the latest built-in control flows, deferrable views, and other advanced functionalities unique to Angular 17.
- Industry Relevance: With Angular continuing to be a sought-after framework in the industry, mastering Angular 17 ensures you remain competitive and relevant in the job market.
- Improved Developer Experience: Angular 17 introduces refinements and enhancements that streamline the development process, providing a more efficient and enjoyable experience for developers.
- Scalability and Maintainability: Learning Angular 17 equips you with the knowledge to build scalable and maintainable applications, crucial factors in modern software development.

### Why Learn Angular 17 in 2023

Angular 17 stands at the forefront of web development frameworks in the current year, offering you several compelling reasons to dive into its intricacies:
Embrace the evolution of web development by mastering Angular 17 in 2023. This advanced version presents you with enhanced performance capabilities, cutting-edge features, and improved developer experiences. Remaining proficient in Angular ensures your relevance in a competitive industry, equipping you with the skills necessary to build scalable, high-performing applications that meet the demands of modern users.

### Course Content Overview

Course Overview:
Total Modules: **5**
Total Lessons: **12**
Total Video Runtime: **1 hour, 41 minutes**

### Summary:
This course is structured into five comprehensive modules, guiding you through the intricacies of Angular 17 Signals. From laying the groundwork with introductory concepts to diving deep into handling HTTP requests, sharing data between components, and culminating with a thorough review in the conclusion module, each section builds upon the last, empowering you to master Angular 17 Signals effectively.

Learn how to surgically manage state and optimize UI rendering with Angular Signals. This course introduces students to the world of Angular Signals, from reactive primitives to seamless interoperability between observables and signals. By the end of this course, you'll have learned how to build a highly performant, lightweight Angular application that features deferrable views, lazy loaded routes, and a PayPal-powered checkout flow. Additionally, you'll have learned the techniques needed to modernize older Angular applications so that they're able to fully leverage the power of Angular Signals.

Demystifying Reactivity with Angular Signals

Fetch data from a REST API making use of Signals.

Make use signals to add functionalities to the shopping cart

Checkout selected items from the cart using the available Signal APIs

How to manage state in an Angular application by making use of Signals

The importance of using Signals to enhance change detection

How to integrate a robust lazy loading approach, by making use of deferrable views and lazy loaded routes

Difference between using RxJS and Signals when working with data and asynchronous operations

How to structure an Angular application using Standalone components

How to work with the newly built-in control flows

Fetching Data with Observables in Angular: A Practical Guide

This article explores the process of fetching data from a server using RxJS, observables, and the Angular framework. It delves into the complexities of working with boilerplate code before accessing and displaying data on a webpage. Additionally, it shows how Angular's probability API can be employed to display data on the page. Finally, it discusses the generation of service files, server integration, and the creation of an interface for data expectation. To bring these concepts to life, a hands-on coding example is used.

Here's the application we'll be building:

In Angular, fetching data often involves the creation and utilization of service files. These files contain functions that call to the server and obtain the desired data. To illustrate, a new service file named "products" is generated within the services folder. The command 

After generating the service file, the HTTP client module needs to be configured, an important tool allowing communication with the REST API. This configuration occurs in the 

 file. Here, the provide HTTP client is imported:

import { provideHttpClient } from '@angular/common/http';

---
title: Fetching Data from the Server using RxJS
description: In this module, you’ll learn how to combine RxJS and Signals when working with HTTP requests from the REST API. We will learn how to work with the Interoperability API when dealing with asynchronous operations in Signals.
code: https://gitlab.com/fullstackio/books/newline-course-apps/fundamentals-of-signals-in-angular-app/-/tree/main/module_3_lesson_2?ref_type=heads
privateVideoUrl: https://stream.mux.com/Lnd7R59vpCypz38n69RFQdW9fq6FEAQBEn2F00o5s2Zw.m3u8
isPublicLesson: true
useMdx: true
---

# Fetching Data with Observables in Angular: A Practical Guide

## Introduction

This article explores the process of fetching data from a server using RxJS, observables, and the Angular framework. It delves into the complexities of working with boilerplate code before accessing and displaying data on a webpage. Additionally, it shows how Angular's probability API can be employed to display data on the page. Finally, it discusses the generation of service files, server integration, and the creation of an interface for data expectation. To bring these concepts to life, a hands-on coding example is used.

Here's the application we'll be building:

<ReplitEmbed src="https://replit.com/@newlineauthors/angularappmodule3lesson2" />

## Data Fetching with Observables

In Angular, fetching data often involves the creation and utilization of service files. These files contain functions that call to the server and obtain the desired data. To illustrate, a new service file named "products" is generated within the services folder. The command `ng generate service` is used to accomplish this.

```bash
ng generate service products
```

## HTTP Client Configuration

After generating the service file, the HTTP client module needs to be configured, an important tool allowing communication with the REST API. This configuration occurs in the `app.config.ts` file. Here, the provide HTTP client is imported:

deji adesoga

The purpose of this lesson is to provide a recap on how data is being fetched

server using ROGS, observables, its exhibits, the fact that we need to deal

boilerplates code before we can have access to the data and display it on the

In the lesson, immediately after this, we are going to make use of signals to

data on the page by making use of the entire probability API. As you can see on

we have a bunch of static data being showed on the page and if I

street to visual studio code, you can see the code being reflected in the

We currently don't have any form of functionality, just a bunch of HTML and CSS

design the page. Currently, we just have the product's components, the navbar

as well as the footer components. We also have our routes, which is ready

We have the product routes, which is the only current routes available. Another

take note of is we currently have our server currently running on port 8000. So

with the integration. First thing I want to do is to generate a new service

I'm going to stop the server and run the command ng generate service and then I

the service inside the services folder and the service is going to be called

have node version 16 in our terminal. We need to make use of node version 18.

So I'm going to make use of mvm use 18 to switch to version 18 of node server.

regenerate the service for the as you can see, we now have the product service

us. Let's head back to Visual Studio could and then configure our provide HTTP

provided HTTP clients allows us to have access to the HTTP clients module,

communicate with our REST API. So this is done inside of the app.config.ts file

providers array, we have right here, we need to import the provided HTTP

provide HTTP clients from at angular slash common slash HTTP. And before we

our life was to generate our environmental variables for the so back in the

I can run the command ng generate environments with this folder, we will be

a REST API URL. So back in Visual Studio code, I'm going to open environment.

And within this object, I'm going to create two keys. The first key is going to

which is going to be set as false. And then we need to configure the API URL.

API on us for URL. And then it's going to be HTTP in lowercase, colon, false,

colon, it's 1000, or slash API, which is the part of our REST API. I'm going to

close that file, as well as the app config file. Then we can add sheets to our

In the services file, before we get started, I would like to import our

as a variable. So to do that, right above, I'm going to say REST API is equals

to make it so bad tick as well as the dollar sign, I'm going to open a bracket

which is imported from the environment.development is going to be environment.

products, which is the end point to get the list of all our product next up in

I'm going to create a private class by saying private HTTP HTTP client. Before

function that helps us to get all the list of products, our like was to create

So within the app directory, I'm going to create a new folder called interface.

interface folder, we're going to create a file code API dash response dot CS

we can type in exports interface. And then the name of our interface, which I'm

products. And this product is the shape in which we expect the data we're

back end. First data is going to be the ID, which is going to be a type of

expect the title, which is going to be a type of string, then we expect a

also going to be a type of string, as well as the price type of number. Then we

discount percentage, which is also going to be a type of number, then we are

the stock, stock is supposed to be a type of number, the brand, a tibri

which is going to be a type of number. And then finally, the quantity, this is

to get from our rest API. I'm going to close the API dash response, those TS

straight to the product service file. So within this file, I'm going to create

get product. And then let's create a gets product function, which is going to