Database - benhall/express-demo

In the Express-demo project, there are several options for connecting to a database. Here are some possibilities and their corresponding examples using the provided documentation and code snippets.

Using SQLite3 with Express-GraphQL:

First, install the required dependencies:

npm install graphql express express-graphql sqlite3 --save

Next, create an instance of the Express app and the SQLite3 database within the current project folder:

const express = require('express');
const sqlite3 = require('sqlite3').verbose();
const ExpressGraphQL = require("express-graphql");
const graphql = require("graphql");

const app = express();
const database = new sqlite3.Database("./my.db");

Create an SQL table within the database:

database.serialize(function() {
database.run(`CREATE TABLE contacts (
id INTEGER PRIMARY KEY,
firstName TEXT,
lastName TEXT,
email TEXT
)`);
});

Define GraphQL types for each contact attribute:

const { GraphQLObjectType, GraphQLString, GraphQLInt, GraphQLID } = graphql;

const ContactType = new GraphQLObjectType({
name: "Contact",
fields: () => ({
id: { type: GraphQLID },
firstName: { type: GraphQLString },
lastName: { type: GraphQLString },
email: { type: GraphQLString },
}),
});

Create a GraphQL schema:

const schema = new graphql.GraphQLSchema({
types: () => [ContactType],
queries: () => ({
contacts: {
type: new GraphQLList(ContactType),
resolve: () => database.all("SELECT * FROM contacts"),
},
}),
});

Set up the GraphQL API server:

const root = { contacts: () => database.all("SELECT * FROM contacts") };
const graphqlHTTP = require("express-graphql");

app.use("/graphql", graphqlHTTP({ schema, rootValue: root }));

app.listen(3333, () => console.log("Server is connected on port 3333"));

Using PostgreSQL with Mongoose:

First, install the required dependencies:

npm install express mongoose --save

Create a database/mongoose.js file for connecting to the PostgreSQL database:

const mongoose = require("mongoose");

mongoose.connect("postgres://username:password@localhost:5432/database_name", {
useNewUrlParser: true,
useUnifiedTopology: true,
});

mongoose.connection.on("error", console.error.bind(console, "MongoDB connection error:"));
mongoose.connection.once("open", () => console.log("MongoDB database connection opened"));

Create a database/models/Patient.js file for defining the Patient schema:

const mongoose = require("mongoose");

const PatientSchema = new mongoose.Schema({
name: String,
age: Number,
});

module.exports = mongoose.model("Patient", PatientSchema);

Use the Mongoose connection and models in the Express app:

const express = require("express");
const mongoose = require("mongoose");
const Patient = require("./database/models/Patient");

const app = express();

mongoose.connect("postgres://username:password@localhost:5433/database_name", {
useNewUrlParser: true,
useUnifiedTopology: true,
});

app.listen(3000, () => console.log("Server is connected on port 3000"));

Using MySQL with Express:

First, install the required dependencies:

npm install express mysql --save

Create a database.js file for connecting to the MySQL database:

const mysql = require("mysql");

const connection = mysql.createConnection({
host: "localhost",
user: "username",
password: "password",
database: "database_name",
});

connection.connect((err) => {
if (err) throw err;
console.log("Connected to MySQL database!");
});

module.exports = connection;

Use the MySQL connection in the Express app:

const express = require("express");
const connection = require("./database");

const app = express();

app.get("/", (req, res) => {
connection.query("SELECT * FROM table_name", (err, results) => {
if (err) throw err;
res.send(results);
});
});

app.listen(3001, () => console.log("Server is connected on port 3001"));