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expresshttpgraphqlapollo-server

can't find installSubscribtionHandlers method in apollo-server-express source code?

How come installSubscriptionHandlers method is not part of apollo-server-express source code and this method is mentioned here in apollo-server docs

  const http = require('http');
  const { ApolloServer } = require('apollo-server-express');

  const express = require('express');

  const app = express();
  const server = new ApolloServer({ typeDefs, resolvers });
  server.applyMiddleware({app})

  const httpServer = http.createServer(app);
  server.installSubscriptionHandlers(httpServer);

This code works and doesn't show any error despite installSubscriptionHandlers being not a method exported from any module in the package source code.

Solution

  • The docs linked to are for apollo-server v2, which is maintained on the version-2 branch of the repo. The default main branch is (at present) used to maintain v3.

    In v2, the method installSubscriptionHandlers exists on the class ApolloServerBase exported from the package apollo-server-core.