Setup and options

Installation

The simplest way to get started with Apollo Angular is by running ng add apollo-angular command.

Installation with Angular Schematics

We support ng-add command now.

To start using Apollo Angular simply run:

ng add apollo-angular

One thing you need to set is the URL of your GraphQL Server, so open src/app/graphql.module.ts and set uri variables:

const uri = 'https://w5xlvm3vzz.lp.gql.zone/graphql'; //our test Graphql Server which returns rates

Done! You can now create your first query, let’s go through it together here

Installation without Angular Schematics

If you want to setup Apollo without the help of Angular Schematics, first, let’s install some packages:

npm install --save apollo-angular \
  apollo-angular-link-http \
  apollo-link \
  apollo-client \
  apollo-cache-inmemory \
  graphql-tag \
  graphql
  • apollo-client: Where the magic happens
  • apollo-angular: Bridge between Angular and Apollo Client
  • apollo-cache-inmemory: Our recommended cache
  • apollo-angular-link-http: An Apollo Link for remote data fetching
  • graphql: Second most important package
  • graphql-tag: Parses your strings to GraphQL documents

The apollo-client package requires AsyncIterable so make sure your tsconfig.json includes esnext.asynciterable:

{
  "compilerOptions": {
    // ...
    "lib": [
      "es2017",
      "dom",
      "esnext.asynciterable"
    ]
  }
}

Great, now that you have all the dependencies you need, let’s create your first Apollo Client.

In our app.module.ts file use ApolloModule and APOLLO_OPTIONS token to configure Apollo Client:

import { HttpClientModule } from "@angular/common/http";
import { ApolloModule, APOLLO_OPTIONS } from "apollo-angular";
import { HttpLinkModule, HttpLink } from "apollo-angular-link-http";
import { InMemoryCache } from "apollo-cache-inmemory";

@NgModule({
  imports: [
    BrowserModule,
    HttpClientModule,
    ApolloModule,
    HttpLinkModule
  ],
  providers: [{
    provide: APOLLO_OPTIONS,
    useFactory(httpLink: HttpLink) {
      return {
        cache: new InMemoryCache(),
        link: httpLink.create({
          uri: "https://w5xlvm3vzz.lp.gql.zone/graphql"
        })
      }
    },
    deps: [HttpLink]
  }],
})
export class AppModule {}

Take a closer look what we did there:

  1. With apollo-angular-link-http and HttpLink service we connect our client to an external GraphQL Server
  2. Thanks to apollo-cache-inmemory and InMemoryCache we have a place to store data in
  3. APOLLO_OPTIONS provides options to Apollo Client

Apollo’s HttpLink requires HttpClient so that’s why we also used HttpClientModule from @angular/common/http.

Apollo Client has a pluggable network interface layer, which can let you configure how queries are sent over HTTP, or replace the whole network part with something completely custom, like a websocket transport, mocked server data, or anything else you can imagine.

One Link that you already have in your application is called apollo-angular-link-http which uses HTTP to send your queries.

apollo-cache-inmemory is the default cache implementation for Apollo Client 2.0. InMemoryCache is a normalized data store that supports all of Apollo Client 1.0’s features without the dependency on Redux.

Request data

Once all is hooked up, you’re ready to start requesting data with Apollo service!

Apollo is an Angular service exported from apollo-angular to share GraphQL data with your UI.

First, pass your GraphQL query wrapped in the gql function (from graphql-tag) to the query property in the Apollo.watchQuery method, in your component. The Apollo service is a regular angular service that you familiar with, data are being streamed through Observables. Same here.

The watchQuery method returns a QueryRef object which has the valueChanges property that is an Observable.

An object passed through an Observable contains loading, error, and data properties. Apollo Client tracks error and loading state for you, which will be reflected in the loading and error properties. Once the result of your query comes back, it will be attached to the data property.

It’s also possible to fetch data only once. The query method of Apollo service returns an Observable that also resolves with the same result as above.

Let’s create an ExchangeRates component to see the Apollo service in action!

Basic Operations

If you want to see how easy it is to fetch data from a GraphQL server with Apollo, you can use the query method. It is as easy as this:

import {Component, OnInit} from '@angular/core';
import {Apollo} from 'apollo-angular';
import gql from 'graphql-tag';

@Component({
  selector: 'exchange-rates',
  template: `
    <div *ngIf="loading">
      Loading...
    </div>
    <div *ngIf="error">
      Error :(
    </div>
    <div *ngIf="rates">
      <div *ngFor="let rate of rates">
        <p>{{rate.currency}}: {{rate.rate}}</p>
      </div>
    </div>
  `,
})
export class ExchangeRates implements OnInit {
  rates: any[];
  loading = true;
  error: any;

  constructor(private apollo: Apollo) {}

  ngOnInit() {
    this.apollo
      .watchQuery({
        query: gql`
          {
            rates(currency: "USD") {
              currency
              rate
            }
          }
        `,
      })
      .valueChanges.subscribe(result => {
        this.rates = result.data && result.data.rates;
        this.loading = result.loading;
        this.error = result.error;
      });
  }
}

Congrats, you just made your first query! 🎉 If you render your ExchangeRates component within your App component from the previous example, you’ll first see a loading indicator and then data on the page once it’s ready. Apollo Client automatically caches this data when it comes back from the server, so you won’t see a loading indicator if you run the same query twice.

If you’d like to play around with the app we just built, you can view it on StackBlitz. Don’t stop there! Try building more components with Apollo service and experimenting with the concepts you just learned.

Next steps

Now that you’ve learned how to fetch data with Apollo Angular, you’re ready to dive deeper into creating more complex queries and mutations. After this section, we recommend moving onto:

  • Queries: Learn how to fetch queries with arguments and dive deeper into configuration options..
  • Mutations: Learn how to update data with mutations and when you’ll need to update the Apollo cache.
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