Apollo Elements Guides API Blog

Getting Started: Apollo Client

Before your components can interact with your graph, they need to connect to an ApolloClient instance. The easiest and simplest way to do that is with <apollo-client>.

<apollo-client> Element

Import @apollo-elements/components/apollo-client and set it up on your page. If you set the uri attribute, <apollo-client> will create its own client instance for you. If you use uri, you can also set the validate-variables boolean attribute to prevent the client from fetching any operation (e.g. query) that does not have all its non-nullable variables set.

<apollo-client uri="/graphql" validate-variables>
  <app-root></app-root>
</apollo-client>

Nested instances of <apollo-client> will control their own decendents

<apollo-client uri="/server-a">
  <query-element>
    <!-- This element queries from /server-a -->
  </query-element>

  <apollo-client uri="/server-b">
    <query-element>
      <!-- This element queries from /server-b -->
    </query-element>
  </apollo-client>

</apollo-client>

<apollo-client> uses the createApolloClient helper from @apollo-elements/lib/create-apollo-client under the hood:

import { createApolloClient } from '@apollo-elements/lib/create-apollo-client';

const client = createApolloClient({
  uri: '/graphql',
  validateVariables: true,
  typePolicies: {
    User: {
      fields: {
        fullName(_, { readField }) {
          return `${readField('firstName')} ${readField('lastName')}`;
        }
      }
    }
  }
});

If you need more control over the client, for example to pass in type policies or to configure the links, you need to construct an instance by importing from @apollo/client/core (note: @apollo/client exports a bunch of react code, so if you leave off the /core, you might experience TypeScript compilation errors, or larger bundle sizes)

// fancy-apollo-client.ts
import { ApolloClient, InMemoryCache, HttpLink, ApolloLink, } from '@apollo/client/core';
import { CustomLink } from './my-custom-link';

const cache =
  new InMemoryCache();

// Configure with a URL to your GraphQL endpoint
const link = ApolloLink.from([
  new CustomLink(),
  new HttpLink({ uri: '/graphql' }),
])

export const client =
  new ApolloClient({ cache, link });

Now that your client is ready, you need a way to connect your components to it. You can use <apollo-client> without a uri attribute:

import { client } from './fancy-apollo-client';
document
  .querySelector('apollo-client#fancy-client')
  .client = client;

See <apollo-client> component docs for more info and examples.

Global Client

If you assign your client to the global variable window.__APOLLO_CLIENT__, all the apollo elements in your app will connect to it. This is also the variable that Apollo Client Developer Tools use to connect to the client.

import { client } from './global-apollo-client';
window.__APOLLO_CLIENT__ = client;

If you'd prefer to avoid assigning to the window, you have more options...

ApolloClientMixin

Import ApolloClientMixin from @apollo-elements/mixins and apply it to your components' classes to connect them to a specific client:

import { ApolloClientMixin, ApolloQueryMixin } from '@apollo-elements/mixins';

import { client } from './specific-apollo-client';

interface Data { /* ... */ }
interface Variables { /* ... */ }

const Base =
  ApolloClientMixin(client, ApolloQueryMixin(HTMLElement));

export class ConnectedQuery extends Base<Data, Variables> { /* ... */ }

customElements.define('connected-query', ConnectedQuery);

import { ApolloClientMixin } from '@apollo-elements/mixins/apollo-client-mixin';
import { ApolloQuery, customElement } from '@apollo-elements/lit-apollo';
import { client } from './specific-apollo-client';

interface Data { /* ... */ }
interface Variables { /* ... */ }

const Base =
  ApolloClientMixin(client, ApolloQuery);

@customElement('connected-query')
export class ConnectedQuery extends Base<Data, Variables> { /* ... */ }

import { ApolloClientMixin } from '@apollo-elements/mixins/apollo-client-mixin';
import { ApolloQuery, customElement } from '@apollo-elements/fast';
import { client } from './specific-apollo-client';

interface Data { /* ... */ }
interface Variables { /* ... */ }

const Base =
  ApolloClientMixin(client, ApolloQuery);

const name = 'connected-query';
const template = html<ConnectedQuery>`...`;

@customElement({ name, template })
export class ConnectedQuery extends Base<Data, Variables> { /* ... */ }

import { useQuery } from '@apollo-elements/haunted';
import { client } from './specific-apollo-client';

interface Data { /* ... */ }
interface Variables { /* ... */ }

// There is no ApolloClientMixin for Haunted, rather
// the `useQuery`, `useMutation`, and `useSubscription` hooks accept a client option.

function ConnectedQuery() {
  const { data } = useQuery(gql`query ConnectedQuery { }`, { client });
}

import { client, query, define, html } from '@apollo-elements/hybrids';
import { client as apolloClient } from './specific-apollo-client';

interface Data { /* ... */ }
interface Variables { /* ... */ }

// There is no ApolloClientMixin for Hybrids, rather
// the `client` factory accepts a client instance.

define('connected-query', {
  client: client(apolloClient),
  query: query(gql`query ConnectedQuery {
    # ...
  }`),
});

Caught a mistake or want to contribute to the documentation? Edit this page on GitHub!