seal-mongo

seal-mongo

seal-mongo makes it easy to connect to MongoDB reliably.

Installation

$ npm install seal-mongo

Quick start

First you need to add a reference to seal-mongo to your application.

const mongo = require('seal-mongo');

Then you can use its db function to connect to a MongoDB server. Provide the connection string and a callback as parameters.

mongo.db('mongodb://localhost:27017/mydb', (err, db) => {
  // ...
});

If no connection can be established, seal-mongo retries to connect ten times, with a pause of 1 second between two connection attempts.

If you need to pass options to the MongoDB connection, e.g. for setting write concerns, provide an additional options object. For details see the MongoClient.connect documentation. Additionally the following options can be set:

• connectionRetries is the number of retries to connect to MongoDB server, a value of 0 tries to connect only once without retries, default is 10.
• waitTimeBetweenRetries is the time in milliseconds waiting between the retries, default is 1000 ms

mongo.db('mongodb://localhost:27017/mydb', {
  connectionRetries: 1
  // ...
}, (err, db) => {
  // ...
});

Now you can use the db object to access the database. Please note that this is the very same object as the one that the node-mongodb-native driver provides.

Please note that if you call db twice with the same connection string, both calls will use the same underlying connection.

Accessing GridFS

If you need to access GridFS, simply call the db object's gridfs function.

const gridfs = db.gridfs();

gridfs.createReadStream

createReadStream(fileName, callback)

• fileName String Name of the file to read
• callback (err, stream, metadata) Function Called on error or when stream is ready

Opens the file fileName for reading and calls callback as soon the file is opened. The callback provides the data of the file as a Readable stream as well as its metadata.

gridfs.createReadStream('My file.txt', (err, stream, metadata) => {
  if (err) {
    throw err;
  }

  const chunk = stream.read();
  // ...
});

gridfs.createWriteStream

createWriteStream(fileName, metadata, callback)

• fileName String Name of the file to write
• metadata Object Optional metadata, can be left out
• callback (err, stream) Function Called on error or when stream is ready

Opens the file fileName for writing and calls callback as soon the file is opened. The content of the file can be written with the Writable stream provided by the callback. The stream emits a close event when all data is written and the file is closed.

Please note: The file content is not fully written when the finish event occurs. So, do not rely on it.

gridfs.createWriteStream('My file.txt', { foo: 'bar' }, (err, stream) => {
  if (err) {
    throw err;
  }

  stream.on('close', (err) => {
    if (err) {
      // Handle error on file close
    }
  });

  stream.write('Hello World');
  stream.end();
});

gridfs.exist

exists(fileName, callback)

• fileName String Name of the file to check
• callback (err, doExist) Function Called on error or when check finished

Checks if file fileName does exist. The callback provides an possible error and a boolean value. If doExist is false the file does not exist, otherwise it exists.

gridfs.exist('My file.txt', (err, doExist) => {
  if (err) {
    throw err;
  }

  if (doExist) {
    // File does exist
  } else {
    // File does not exist
  }
});

gridfs.unlink

unlink(fileName, callback)

• fileName String Name of the file to delete
• callback (err, fileFound) Function Called on error or delete finished

Deletes the file fileName. The callback provides an error object if the unlink operation fails. Otherwise the fileFound indicates whether the file did exist or not.

gridfs.unlink('My file.txt', (err, fileFound) => {
  if (err) {
    throw err;
  }

  if (fileFound) {
    // File did exist and has been removed
  } else {
    // File does not exist
  }
});

TLS

The module uses plossys/seal-tlscert to obtain certificates for an encrypted connection to the database. The connection will only be encrypted if TLS_UNPROTECTED is set to none or loopback. Otherwise it is assumed that an unencrypted connection is save. If seal-tlscert provides a CA certificate, the host's certificate will be transmitted to the database server in order to allow client verification.

Running the build

To build this module use roboter.

'''bash $ bot '''