Usage: 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>

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>

See <apollo-client> guide 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...

Controllers' `client` Parameter

Pass the client param to controllers to specify the client instance

<blink>
The HTML Apollo Elements use the ApolloElement interface. See the previous segments.
</blink>

import { ApolloQueryController } from '@apollo-elements/core';
import { ControllerHostMixin } from '@apollo-elements/mixins';
import { MyQuery } from './My.query.graphql';
import { client } from './specific-apollo-client';

export class ConnectedQuery extends ControllerHostMixin(HTMLElement) {
  query = new ApolloQueryController(this, MyQuery, { client });
}

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

import { ApolloQueryController } from '@apollo-elements/core';
import { LitElement } from 'lit';
import { customElement } from 'lit/decorators.js';
import { MyQuery } from './My.query.graphql';
import { client } from './specific-apollo-client';

@customElement('connected-query')
export class ConnectedQuery extends LitElement {
  query = new ApolloQueryController(this, MyQuery, { client });
}

import { ApolloQueryBehavior } from '@apollo-elements/fast';
import { FASTElement, customElement } from '@microsoft/fast-element';
import { MyQuery } from './My.query.graphql';
import { client } from './specific-apollo-client';

@customElement({ name: 'connected-query' })
export class ConnectedQuery extends FASTElement {
  query = new ApolloQueryBehavior(this, MyQuery, { client });
}

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

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

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

function ConnectedQuery() {
  const { data } = useQuery(gql`query ConnectedQuery { connected }`, { client });
  return <host>...</host>;
}

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

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

Elements' `ApolloClientMixin`

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

<blink>
There is no equivalent of <code>ApolloClientMixin</code> for HTML,
so just use the <code>&lt;apollo-client&gt;</code> element.
</blink>

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 } from '@apollo-elements/fast/bases/apollo-query';
import { customElement, ViewTemplate } from '@apollo-elements/fast';
import { client } from './specific-apollo-client';

const Base =
  ApolloClientMixin(client, ApolloQuery);

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

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

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

// 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 { connected }`, { client });
}

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

// 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 { connected }`, { client });
  return <host>...</host>;
}

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

// There is no ApolloClientMixin for Hybrids, rather pass the client
// to the `query`, `mutation`, or `subscription` factory.

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

Next Steps

Learn more about the <apollo-client> HTML element
Learn how to write query components