How to validate token from Localstorage and return currentUser from Apollo Server to React front-end?

Question

I already have a jwt middleware which verifies token and returns currentUser to React front-end:

app.use(async (req, res, next) => {
    const token = req.headers['authorization'];
    if(token !== "null") {
        try{
            const currentUser = await jwt.verify(token, process.env.SECRET)
        } catch {
        console.error(err);
    }
}
next();
});

Now, I want to integrate the logic into the following Apollo server:

const app = express();
const server = new ApolloServer({
  typeDefs: gql(typeDefs),
  resolvers,
  context: async () =>({ 
  db,
  secret: process.env.SECRET,
  }),
});

app.use(cors(corsOptions));
server.applyMiddleware({ app });

At the end, the value of currentUser should be available to be used at react front-end.
How can I achieve this?

Answer 1

You can add the currentUser to the request object inside the middleware. Next, you pass it copy it from the request to the GraphQL context. Then you can add a currentUser resolver and simply return the user from the context.

Your middlware

app.use(async (req, res, next) => {
    const token = req.headers['authorization'];
    if(token !== "null") {
        try{
            req.currentUser = await jwt.verify(token, process.env.SECRET)
        } catch {
        console.error(err);
    }
}
next();
});

Your server

const app = express();
const server = new ApolloServer({
  typeDefs: gql(typeDefs),
  resolvers,
  context: ({ req }) =>({ 
    currentUser: req.currentUser,
    db,
    secret: process.env.SECRET,
  }),
});

app.use(cors(corsOptions));
server.applyMiddleware({ app });

and the resolvers

const resolvers = {
  Query: {
    currentUser: (parent, args, context) => context.currentUser,
    ...
  }
}

Add the corresponding type definition and you should be able to query the current user from your client.

If you need more information here is a detailed tutorial which might be of help.