In the fast-paced world of web development, creating applications that respond instantly to user interactions is crucial. This is where optimistic UI techniques come into play, especially when integrating Apollo Boost with Angular. By leveraging the power of GraphQL, developers can create seamless and responsive experiences that enhance user satisfaction. In this article, we will explore how to build an optimistic UI in Angular using Apollo Boost, focusing on querying and mutating data efficiently.

What is Apollo Boost?

Apollo Boost is a client library designed for easy integration of GraphQL into your Angular applications. It streamlines the setup process, enabling developers to focus on building rich interfaces rather than wrestling with the complexities of state management and data fetching. With Apollo Boost, you can take advantage of features like caching, optimistic UI updates, and easy integration with various back-end data sources.

Optimistic Updates: A Brief Overview

Optimistic updates refer to the technique where the UI instantly reflects changes that the user makes, assuming those changes will succeed on the server. This approach is particularly useful in scenarios where latency could degrade the user experience. For instance, in social media applications, when a user likes a tweet, a visual indication should appear immediately instead of waiting for the server’s response.

Benefits of Optimistic UI

• Instant Feedback: Users receive immediate confirmation that their actions were successful, improving the overall experience.
• Reduced Latency Perception: By updating the UI optimistically, users feel that the application is faster and more responsive.
• Error Handling: If an error occurs during communication with the server, the application can revert to the previous state seamlessly.

Setting Up Your Angular Application

To get started with building an optimistic UI, ensure you have an existing Angular application integrated with a GraphQL server. If you haven’t set up a GraphQL server yet, you might want to check previous tutorials that cover this aspect. Once you have your server ready, follow these steps:

Step 1: Install Apollo Boost and Dependencies

In your Angular project, you will need to install Apollo Boost, along with the necessary GraphQL dependencies. You can do this using npm:

npm install apollo-angular apollo-client apollo-angular-hooks graphql --save

Step 2: Configure Apollo Client

Next, you need to set up Apollo Client within your Angular application. Create a new Angular module, import Apollo Boost, and add it to your imports array. Here’s a sample setup:

import { NgModule } from '@angular/core';
import { ApolloBoost } from 'apollo-boost';

@NgModule({
  imports: [
    ApolloBoost,
  ],
})
export class GraphQLModule {
  constructor() {
    const client = new ApolloBoost({
      uri: 'http://localhost:4000/graphql',
    });
  }
}

Make sure to replace the URI with the address of your running GraphQL server.

Step 3: Define Your GraphQL Schema

In GraphQL, updating data is done through mutations. You will need to define a mutation query that will handle liking a tweet. Here’s a simple example of a mutation query:

mutation LikeTweet($id: ID!) {
  likeTweet(id: $id) {
    id
    likeCount
  }
}

This query will increment the like count of a specified tweet.

Implementing the Optimistic Response

In your Angular component, you can utilize Apollo to send the mutation and handle the optimistic response. Here’s how you can implement this:

Step 4: Create Observable for Tweets

Start by defining an observable to fetch the tweets from the GraphQL server:

import { Component } from '@angular/core';
import { Apollo } from 'apollo-angular';
import { Observable } from 'rxjs';

@Component({
  selector: 'app-tweets',
  templateUrl: './tweets.component.html',
})
export class TweetsComponent {
  tweets$: Observable<any>;

  constructor(private apollo: Apollo) {
    this.tweets$ = this.apollo.watchQuery({
      query: GET_TWEETS_QUERY,
    }).valueChanges;
  }
}

This observable will keep track of the tweets data and automatically update when there are changes.

Step 5: Handle the Like Action with Optimistic Response

When a user clicks the like button, you can call the mutation. Here’s an example of how you can implement optimistic updates:

likeTweet(tweetId: string) {
  this.apollo.mutate({
    mutation: LIKE_TWEET_MUTATION,
    variables: { id: tweetId },
    optimisticResponse: {
      likeTweet: {
        id: tweetId,
        likeCount: currentLikeCount + 1,
        __typename: 'Tweet',
      },
    },
  }).subscribe();
}

In this code, optimisticResponse is set to immediately reflect the change on the UI as if the server processed it successfully.

Rendering the UI

Finally, you can render the tweets and the like button in your component’s HTML template:

<ul>
  <li *ngFor="let tweet of (tweets$ | async)?.data.tweets">
    <p>{{ tweet.text }}</p>
    <button (click)="likeTweet(tweet.id)">
      Like ({{ tweet.likeCount }})
    </button>
  </li>
</ul>

This template loops through the list of tweets and provides a button to like each tweet, updating the like count instantly.

Conclusion

Building an optimistic UI using Apollo Boost in Angular can significantly enhance the user experience by making applications feel faster and more responsive. By implementing these techniques, developers can ensure that their applications not only perform well but also delight users with smooth interactions.

If you want to dive deeper into optimizations and advanced features with Apollo and Angular, consider subscribing to our channel or checking additional resources on Angular Firebase.

Join the conversation! Tell us how you implement optimistic UI updates in your applications.