Gain insights into reactive programming with RxJS 7, explore data streams, error handling, and multicasting to build a recipe app, and learn to test and optimize reactive applications.

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The reactive programming paradigm is designed to make working with asynchronous events and data streams convenient. 

This course teaches you about the reactive programming paradigm and when to choose it over others. You’ll learn to use new RxJS 7 features to create a recipe book web application that lets users browse and share recipes. In this context, you’ll learn about data streams, error handling, and how to combine streams and transform one data stream into another. You’ll develop an understanding of multicasting and caching streams, how to share data between components, perform bulk operations such as file uploads, and perform real-time updates. Finally, you’ll learn how to test a reactive application. To assess your knowledge, there’s a project, coding challenges, and assessments.

After this course, you’ll be able to determine the utility of the reactive paradigm for any application and have mastery over new RxJS 7 features to create robust reactive applications.

Reactive Programming with Angular and RxJS 7

#
The idea behind the reactive pattern for managing unsubscriptions is to keep and use the observable as a stream throughout the application. Don't worry, this will become more apparent to you later in this section.

# Retrieving data as streams

So instead of defining a method to retrieve our data, we'll declare a variable inside our service in the `src/app/core/services/recipes.service.ts` file.

import { Injectable } from "@angular/core";
import { HttpClient } from "@angular/common/http";
import { Observable } from "rxjs";
import { Recipe } from "../model/recipe";
import { environment } from "src/environments/environment";
const BASE_PATH = environment.basePath;
@Injectable({
  providedIn: "root",
})
export class RecipesService {
  recipes$ = this.http.get<Recipe[]>(`${BASE_PATH}/recipes`);
  constructor(private http: HttpClient) {}
}

Here, we're declaring the `recipes$` variable as the result of HTTP GET, as shown in **line 11** in the above code, which is either an observable or the data stream.

# Defining the stream in the component

Now, in `RecipesListComponent` in the `src/app/recipes-list/recipes-list.component.ts` file, we're going to do the same thing we did in the classic pattern—that is, declaring a variable holding the stream returned from our service. This time, the variable is an observable.

Here, we're declaring the `recipes＄` variable as the result of HTTP GET, as shown in **line 11** in the above code, which is either an observable or the data stream.

# Defining the stream in the component

Now, in `RecipesListComponent` in the `src/app/recipes-list/recipes-list.component.ts` file, we're going to do the same thing we did in the classic pattern—that is, declaring a variable holding the stream returned from our service. This time, the variable is an observable.

Learn about the reactive pattern for fetching data.

Getting Started

The Power of the Reactive Paradigm

RxJS 7—The Major Features

A Walk-Through of the Application

Fetching Data as Streams

Error Handling

Combining Streams

Assessment 1

Transforming Streams

Multicasting Essentials

Caching Streams

Sharing Data between Components

Bulk Operations

Processing Real-Time Updates

Testing RxJS Observables

Assessment 2

Conclusion

Reactive Pattern for Fetching Data

Retrieving data as streams