apollo-server/docs/source/migration-two-dot.md

title	description
Migrating to v2.0 Release Candidate	How to migrate to Apollo Server 2.0 rc

The Apollo Server 2.0 release candidate dramatically simplifies the API for building a GraphQL server without compromising on features. It's also completely backward compatible, so you don't have to worry about breaking changes when upgrading.

While it's possible to migrate an existing server to the 2.0 release candidate without any changes, we recommend changing to new patterns we're suggesting in order to take advantage of all the latest Apollo Server features, reduce the boilerplate, and enable future flexibility. To learn how to migrate to the 2.0 release candidate from version 1.0, please read the following guide.

Note: In the release candidate of Apollo Server 2.0 only Express and Hapi are supported. Additional integrations will be implemented in the official 2.0 release.

The `gql` tag

Apollo Server 2.0 ships with the gql tag for editor syntax highlighting and auto-formatting with Prettier. In the future, we will be using it for statically analyzing GraphQL queries, so Apollo Servers requires wrapping your schema with gql.

The gql tag parses the query string into an AST and is now exported from the new apollo-server package.

const { ApolloServer, gql } = require('apollo-server');

const typeDefs = gql`
  type Query {
    hello: String
  }
`;

//Some projects use schemas imported from external files
const fs = require('fs');
const typeDefs = gql`${fs.readFileSync(__dirname.concat('/schema.graphql'), 'utf8')}`;

//gql can also be used as regular function to convert a string to an AST
const typeDefs = gql(fs.readFileSync(__dirname.concat('/schema.graphql'), 'utf8'))

Changes to app dependencies

Apollo Server 2.0 RC requires Node.js v6 and higher.

Apollo Server 2.0 simplifies implementing a GraphQL server. Apollo Server 1.0 revolved around providing middleware-based solutions, which had to be added to an application which already existed. These middleware implementations were tied to the HTTP server in use (e.g. apollo-server-express for Express implementations, apollo-server-hapi for hapi, etc.).

There is a consideration to be made when following the rest of the guide:

• Middleware option: If the application being migrated implements Apollo Server alongside other middleware, there are some packages which can be removed, but adding the apollo-server-{integration} package and switching to using the new applyMiddleware API should still simplify the setup. In this case, check the Middleware section.
• Stand-alone option: If the application being migrated is only used as a GraphQL server, Apollo Server 2.0 eliminates the need to run a separate HTTP server and allows some dependencies to be removed. In these cases, the Stand-alone option will reduce the amount of code necessary for running a GraphQL server.

Simplified usage

Check out the following changes for Apollo Server 2.0 RC.

• You no longer need to import body-parser to set up apollo-server-express.
• You no longer need to import makeExecutableSchema from graphql-tools.
• You no longer need to import graphqlExpress and graphiqlExpress from apollo-server-express.
• You should pass in typeDefs and resolvers as parameters to an instance of Apollo Server.
• If the server is only functioning as a GraphQL server, it's no longer necessary to run your own HTTP server (like express).

Middleware

With the middleware option used by Apollo Server 1.0 users, it is necessary to install the release candidate version of apollo-server-express. To do this, use the rc tag when installing:

npm install --save apollo-server-express@rc

The changes are best shown by comparing the before and after of the application.

Apollo Server 1 (old pattern)

An example of using Apollo Server 1 with the Express framework:

const express = require('express');
const bodyParser = require('body-parser');
const { makeExecutableSchema } = require('graphql-tools');
const { graphqlExpress } = require('apollo-server-express');

const typeDefs = `
  type Query {
    hello: String
  }
`;

const resolvers = {
  Query: {
    hello: () => 'Hello world!'
  },
}

const myGraphQLSchema = makeExecutableSchema({
  typeDefs,
  resolvers,
});

const PORT = 3000;

const app = express();

// bodyParser is needed just for POST.
app.use('/graphql', bodyParser.json(), graphqlExpress({ schema: myGraphQLSchema }));

app.listen(PORT);

Apollo Server 2 (new pattern)

Now, you can just do this instead:

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

const app = express();

const typeDefs = gql`
  type Query {
    hello: String
  }
`;

const resolvers = {
  Query: {
    hello: () => 'Hello world!'
  },
};

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

app.listen({ port: 4000 }, () =>
  console.log(`🚀 Server ready at http://localhost:4000${server.graphqlPath}`)
)

Stand-alone

For starting a production-ready GraphQL server quickly, Apollo Server 2.0 ships with a built-in server, so starting a server (e.g. Express, Koa, etc.) is no longer necessary.

For these cases, it's possible to remove the existing apollo-server-{integrations} package and add the new apollo-server release candidate. If using Express, this can be done by running:

npm uninstall --save apollo-server-express

npm install --save apollo-server@rc

An implementation with this pattern would look like:

const { ApolloServer, gql } = require('apollo-server');

// Construct a schema, using GraphQL schema language
const typeDefs = gql`
  type Query {
    announcement: String
  }
`;

// Provide resolver functions for your schema fields
const resolvers = {
  Query: {
    announcement: () =>
      `Say hello to the new Apollo Server! A production ready GraphQL server with an incredible getting started experience.`
  }
};

const server = new ApolloServer({ typeDefs, resolvers });

server.listen().then(({ url }) => {
  console.log(`🚀 Server ready at ${url}`);
});

Adding Additional Middleware to Apollo Server 2

For middleware that is collocated with the GraphQL endpoint, Apollo Server 2 allows middleware mounted on the same path before applyMiddleware is called. For example, this server runs an authentication middleware before GraphQL execution.

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

const app = express();
const path = '/graphql';

const server = new ApolloServer({ typeDefs, resolvers });

//Mount a jwt or other authentication middleware that is run before the GraphQL execution
app.use(path, jwtCheck);

server.applyMiddleware({ app, path });

app.listen({ port: 4000 }, () =>
  console.log(`🚀 Server ready at http://localhost:4000${server.graphqlPath}`)
)

Using an Existing Schema

For many existing instances of Apollo Server, the schema is created at runtime before server startup, using makeExecutableSchema or mergeSchemas. Apollo Server 2 stays backwards compatible with these more complex schemas, accepting it as the schema field in the server constructor options. Additionally, Apollo Server 2 exports all of graphql-tools, so makeExecutableSchema and other functions can be imported directly from Apollo Server.

Note: the string to create these schema will not use the gql tag exported from apollo-server.

const { ApolloServer, makeExecutableSchema, gql } = require('apollo-server');

//For developer tooling, such as autoformatting, use the following workaround
const gql = String.raw;

const typeDefs = gql`
  type Query {
    hello: String
  }
`;

const schema = makeExecutableSchema({
  typeDefs,
  resolvers,
});
//mergeSchemas can be imported from apollo-server
//const schema = mergeSchemas(...);

const server = new ApolloServer({ schema });

server.listen().then(({ url }) => {
  console.log(`🚀 Server ready at ${url}`);
});

Accessing Request Headers

Apollo Server 1 allowed request headers to be used in the construction of the GraphQL options. Apollo Server 2 allows constructor to create the context based upon the request.

//old way
graphqlExpress((req, res) => ({
  schema: myGraphQLSchema,
  context: {
    token: req.headers['auth-token'],
  },
}))

//new way
new ApolloServer({
  schema: myGraphQLSchema,
  context: ({req, res}) => ({
    token: req.headers['auth-token'],
  }),
});

For most other functions that might have required access to the middleware arguments, such as formatParams, formatError, and formatResponse, it is possible to create a graphql-extension.

For more complicated use cases, the ApolloServer class can be extended to override the createGraphQLServerOptions function to create parameters based on the same argument that's passed to the context.

Replacing `logFunction`

Apollo Server 2 removes the logFunction in favor of using graphql-extensions, which provides a more structured and flexible way of instrumenting Apollo Server. The explanation of how to do this more granular logging, can be found in the metrics section

Replacing GraphiQL

Apollo Server 2 ships with GraphQL Playground instead of GraphiQL and collocates the gui with the endpoint. GraphQL playground can be customized in the following manner.

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

const server = new ApolloServer({
  // These will be defined for both new or existing servers
  typeDefs,
  resolvers,
});

server.applyMiddleware({
  app, // app is from an existing express app
  gui: {
    endpoint?: string
    subscriptionEndpoint?: string
    tabs: [
      {
        endpoint: string
        query: string
        variables?: string
        responses?: string[]
        headers?: { [key: string]: string }
      },
    ],
  }
});

app.listen({ port: 4000 }, () =>
  console.log(`🚀 Server ready at http://localhost:4000${server.graphqlPath}`)
)

Some Apollo Server 1 implementations use a custom version of GraphiQL, which can be added to Apollo Server 2 as a middleware or ported to use the React version of GraphQL Playground.