apollo_example.js

import ApolloClient from 'apollo-client';
import { getOperationAST } from 'graphql';
import { ApolloLink } from 'apollo-link';
import { HttpLink } from 'apollo-link-http';
import { WebSocketLink } from 'apollo-link-ws';
import { InMemoryCache } from 'apollo-cache-inmemory';
import fetch from 'isomorphic-fetch';
import WebSocket from 'ws';

let apolloClient = null;

if (!process.browser) {
  global.fetch = fetch;
}

const initNetworkInterface = (headers) => {
  const httpLink = new HttpLink({
    uri: `${process.env.API_HOST}/graphql`,
    headers,
    credentials: 'include',
  });

  const wsLink = new WebSocketLink({
    uri: `${process.env.SOCKET_API}/subscriptions`,
    options: {
      reconnect: true,
    },
    webSocketImpl: !process.browser && WebSocket,
  });

  const link = ApolloLink.split(
    (operation) => {
      const operationAST = getOperationAST(operation.query, operation.operationName);
      return !!operationAST && operationAST.operation === 'subscription';
    },
    wsLink,
    httpLink,
  );

  return link;
};

const createClient = (initialState, headers) =>
  new ApolloClient({
    ssrMode: !process.browser,
    ssrForceFetchDelay: 100,
    link: initNetworkInterface(headers),
    cache: new InMemoryCache().restore(initialState),
  });

export default (initialState, headers) => {
  if (!process.browser) {
    return createClient(initialState, headers);
  }
  if (!apolloClient) {
    apolloClient = createClient(initialState, headers);
  }
  return apolloClient;
};