Where the db arg comes from in the context?

[os-guild]

Where the db arg comes from in the context?

[ShynRou]

My implenentation with express:

  const MongoClient = mongodb.MongoClient;
  let db;

  try {
    let client = await MongoClient.connect(config.db.url);
    db = client.db(config.db.database);
  } catch (error) {
    console.error(error);
    process.exit(1);
  }

  const app = express();

  app.use('/graphql',
    graphqlHTTP({
        schema: Schema,
        rootValue: {},
        graphiql: true,
        context: { db },
        formatError: (err) => {
          console.log(err);
          return err;
        }
      })
  );
  app.listen(config.server.port);

[ahsath]

It is safe to pass the db instance even before /graphql?

[ShynRou]

Yeah, my init function is async so I use await to make sure the MongoDB connection is established before moving on to initialization.

[ahsath]

How do you handle database connection errors to the client?

[ShynRou]

I close the server since it wont work without, and let it restart via forever or pm2 until it reestablishes a connection.

   } catch (error) {
    console.error(error);
    process.exit(1);
  }

[yoavkarako]

There's no real right or wrong here; it's simply not within the package's scope to decide how you should do this. It also isn't necessary for the DB connection to reside in the context. Once in the resolve callback, you may acquire it however you prefer.

@ShynRou's implementation is a valid example.
Another example:

import connection from '...'

connection.then(db => {
    app.use('/',
        graphqlHTTP({
            context: { db },
            ...
        }));
}).catch(err =>{
    ...
});