InfluxDB and MongoDB from GraphQL

Here's an example of how you can use GraphQL to combine calls to MongoDB and InfluxDB data sources using TypeScript:

import { ApolloServer, gql } from 'apollo-server';
import { MongoClient } from 'mongodb';
import { createInfluxGraphQLSchema } from 'influx-graphql';
import Influx from 'influx';

// Create a new MongoDB client instance
const mongoClient = new MongoClient('mongodb://localhost:27017', { useNewUrlParser: true });

// Create a new InfluxDB client instance
const influx = new Influx.InfluxDB({
  host: 'localhost',
  database: 'mydb',
});

// Connect to the MongoDB client and start the InfluxDB client
Promise.all([
  mongoClient.connect(),
  influx.ping(),
]).then(() => {
  console.log('Connected to MongoDB and InfluxDB');
}).catch((error: Error) => {
  console.error('Error connecting to MongoDB and InfluxDB:', error);
});

// Define a GraphQL schema for MongoDB using Apollo Server
const mongoSchema = gql`
  type User {
    id: ID!
    name: String!
    email: String!
  }

  type Query {
    user(id: ID!): User
  }
`;

// Define resolvers for the MongoDB schema
const mongoResolvers = {
  Query: {
    user: async (parent: any, args: { id: string }, context: { db: any }) => {
      const user = await context.db.collection('users').findOne({ _id: args.id });
      return {
        id: user._id,
        name: user.name,
        email: user.email,
      };
    },
  },
};

// Create a GraphQL schema for InfluxDB using influx-graphql
const influxSchema = createInfluxGraphQLSchema({
  // Specify the InfluxDB client instance
  influx,
  // Specify the database to use
  database: 'mydb',
});

// Define a GraphQL schema that combines the MongoDB and InfluxDB schemas
const schema = gql`
  type User {
    id: ID!
    name: String!
    email: String!
    lastLogin: Float!
  }

  type Query {
    user(id: ID!): User
  }
`;

// Define resolvers for the combined schema
const resolvers = {
  Query: {
    user: async (parent: any, args: { id: string }, context: { db: any }) => {
      const user = await context.db.collection('users').findOne({ _id: args.id });
      const lastLogin = await influx.query(`
        SELECT last("login") AS "lastLogin"
        FROM "logins"
        WHERE "userId" = '${args.id}'
        GROUP BY time(1d)
        ORDER BY time DESC
        LIMIT 1
      `);
      return {
        id: user._id,
        name: user.name,
        email: user.email,
        lastLogin: lastLogin[0]?.lastLogin ?? 0,
      };
    },
  },
};

// Create an Apollo Server instance with the combined schema and resolvers
const server = new ApolloServer({
  typeDefs: schema,
  resolvers,
  context: () => ({
    db: mongoClient.db('mydb'),
  }),
});

// Start the Apollo Server
server.listen().then(({ url }) => {
  console.log(`Server running at ${url}`);

In this example, we use TypeScript and the "apollo-server", "mongodb", "influx-graphql", and "influx" packages to create a GraphQL server that combines calls to MongoDB and InfluxDB data sources.