Datenbankintegration

Hinzufügen der Möglichkeit, Datenbanken mit Express-Apps zu verbinden, ist nur eine Frage des Laden eines geeigneten Node.js Treibers für die Datenbank in Ihrer App. Dieses Dokument erklärt kurz wie Sie einige der beliebtesten Node.js-Module für Datenbanksysteme in Ihrer Express-App hinzufügen und nutzen:

Cassandra
Couchbase
CouchDB
LevelDB
MySQL
MongoDB
Neo4j
Oracle
PostgreSQL
Redis
SQL Server
SQLite
Elasticsearch

Diese Datenbanktreiber sind unter vielen verfügbar. Für andere Optionen suchen Sie auf der npm Seite.

Cassandra

Modul: cassandra-driver

Installation

$ npm install cassandra-driver

Beispiel

const cassandra = require('cassandra-driver');
const client = new cassandra.Client({ contactPoints: ['localhost'] });

client.execute('select key from system.local', (err, result) => {
  if (err) throw err;
  console.log(result.rows[0]);
});

Couchbase

Modul: couchnode

Installation

$ npm install couchbase

Beispiel

const couchbase = require('couchbase');
const bucket = new couchbase.Cluster('http://localhost:8091').openBucket('bucketName');

// add a document to a bucket
bucket.insert('document-key', { name: 'Matt', shoeSize: 13 }, (err, result) => {
  if (err) {
    console.log(err);
  } else {
    console.log(result);
  }
});

// get all documents with shoe size 13
const n1ql = 'SELECT d.* FROM `bucketName` d WHERE shoeSize = $1';
const query = N1qlQuery.fromString(n1ql);
bucket.query(query, [13], (err, result) => {
  if (err) {
    console.log(err);
  } else {
    console.log(result);
  }
});

CouchDB

Modul: nano

Installation

$ npm install nano

Beispiel

const nano = require('nano')('http://localhost:5984');
nano.db.create('books');
const books = nano.db.use('books');

// Insert a book document in the books database
books.insert({ name: 'The Art of war' }, null, (err, body) => {
  if (err) {
    console.log(err);
  } else {
    console.log(body);
  }
});

// Get a list of all books
books.list((err, body) => {
  if (err) {
    console.log(err);
  } else {
    console.log(body.rows);
  }
});

LevelDB

Modul: levelup

Installation

$ npm install level levelup leveldown

Beispiel

const levelup = require('levelup');
const db = levelup('./mydb');

db.put('name', 'LevelUP', (err) => {
  if (err) return console.log('Ooops!', err);

  db.get('name', (err, value) => {
    if (err) return console.log('Ooops!', err);

    console.log(`name=${value}`);
  });
});

MySQL

Modul: mysql

Installation

$ npm install mysql

Beispiel

const mysql = require('mysql');
const connection = mysql.createConnection({
  host: 'localhost',
  user: 'dbuser',
  password: 's3kreee7',
  database: 'my_db',
});

connection.connect();

connection.query('SELECT 1 + 1 AS solution', (err, rows, fields) => {
  if (err) throw err;

  console.log('The solution is: ', rows[0].solution);
});

connection.end();

MongoDB

Modul: mongodb

Installation

$ npm install mongodb

Beispiel (v2.*)

const MongoClient = require('mongodb').MongoClient;

MongoClient.connect('mongodb://localhost:27017/animals', (err, db) => {
  if (err) throw err;

  db.collection('mammals')
    .find()
    .toArray((err, result) => {
      if (err) throw err;

      console.log(result);
    });
});

Beispiel (v3.*)

const MongoClient = require('mongodb').MongoClient;

MongoClient.connect('mongodb://localhost:27017/animals', (err, client) => {
  if (err) throw err;

  const db = client.db('animals');

  db.collection('mammals')
    .find()
    .toArray((err, result) => {
      if (err) throw err;

      console.log(result);
    });
});

Wenn du einen Objektmodelltreiber für MongoDB möchtest, schau dir [Mongoose]an (https://github.com/LearnBoost/mongoose).

Neo4j

Modul: neo4j-driver

Installation

$ npm install neo4j-driver

Beispiel

const neo4j = require('neo4j-driver');
const driver = neo4j.driver('neo4j://localhost:7687', neo4j.auth.basic('neo4j', 'letmein'));

const session = driver.session();

session.readTransaction((tx) => {
  return tx
    .run('MATCH (n) RETURN count(n) AS count')
    .then((res) => {
      console.log(res.records[0].get('count'));
    })
    .catch((error) => {
      console.log(error);
    });
});

Jürgen

Modul: oracledb

Installation

HINWEIS: Siehe die Installationsvoraussetzungen.

$ npm install oracledb

Beispiel

const oracledb = require('oracledb');
const config = {
  user: '<your db user>',
  password: '<your db password>',
  connectString: 'localhost:1521/orcl',
};

async function getEmployee(empId) {
  let conn;

  try {
    conn = await oracledb.getConnection(config);

    const result = await conn.execute('select * from employees where employee_id = :id', [empId]);

    console.log(result.rows[0]);
  } catch (err) {
    console.log('Ouch!', err);
  } finally {
    if (conn) {
      // conn assignment worked, need to close
      await conn.close();
    }
  }
}

getEmployee(101);

PostgreSQL

Modul: pg-promise

Installation

$ npm install pg-promise

Beispiel

const pgp = require('pg-promise')(/* options */);
const db = pgp('postgres://username:password@host:port/database');

db.one('SELECT $1 AS value', 123)
  .then((data) => {
    console.log('DATA:', data.value);
  })
  .catch((error) => {
    console.log('ERROR:', error);
  });

Redis

Modul: redis

Installation

$ npm install redis

Beispiel

const redis = require('redis');
const client = redis.createClient();

client.on('error', (err) => {
  console.log(`Error ${err}`);
});

client.set('string key', 'string val', redis.print);
client.hset('hash key', 'hashtest 1', 'some value', redis.print);
client.hset(['hash key', 'hashtest 2', 'some other value'], redis.print);

client.hkeys('hash key', (err, replies) => {
  console.log(`${replies.length} replies:`);

  replies.forEach((reply, i) => {
    console.log(`    ${i}: ${reply}`);
  });

  client.quit();
});

SQL-Server

Modul: tedious

Installation

$ npm install tedious

Beispiel

const Connection = require('tedious').Connection;
const Request = require('tedious').Request;

const config = {
  server: 'localhost',
  authentication: {
    type: 'default',
    options: {
      userName: 'your_username', // update me
      password: 'your_password', // update me
    },
  },
};

const connection = new Connection(config);

connection.on('connect', (err) => {
  if (err) {
    console.log(err);
  } else {
    executeStatement();
  }
});

function executeStatement() {
  request = new Request("select 123, 'hello world'", (err, rowCount) => {
    if (err) {
      console.log(err);
    } else {
      console.log(`${rowCount} rows`);
    }
    connection.close();
  });

  request.on('row', (columns) => {
    columns.forEach((column) => {
      if (column.value === null) {
        console.log('NULL');
      } else {
        console.log(column.value);
      }
    });
  });

  connection.execSql(request);
}

SQLite

Modul: sqlite3

Installation

$ npm install sqlite3

Beispiel

const sqlite3 = require('sqlite3').verbose();
const db = new sqlite3.Database(':memory:');

db.serialize(() => {
  db.run('CREATE TABLE lorem (info TEXT)');
  const stmt = db.prepare('INSERT INTO lorem VALUES (?)');

  for (let i = 0; i < 10; i++) {
    stmt.run(`Ipsum ${i}`);
  }

  stmt.finalize();

  db.each('SELECT rowid AS id, info FROM lorem', (err, row) => {
    console.log(`${row.id}: ${row.info}`);
  });
});

db.close();

Elasticsearch

Modul: elasticsearch

Installation

$ npm install elasticsearch

Beispiel

const elasticsearch = require('elasticsearch');
const client = elasticsearch.Client({
  host: 'localhost:9200',
});

client
  .search({
    index: 'books',
    type: 'book',
    body: {
      query: {
        multi_match: {
          query: 'express js',
          fields: ['title', 'description'],
        },
      },
    },
  })
  .then(
    (response) => {
      const hits = response.hits.hits;
    },
    (error) => {
      console.trace(error.message);
    }
  );