Node.js and managing MongoDB databases

Question

I need your advice.

I want to handle server with multiple MongoDB databases and managing them throw rest API (node.js).

How can I manage my databases? Connect to all databases when server up is not a good idea. Connect to the database for creating a document in DB and disconnect after this also don’t sound like a good idea... So how can I do it? Store an array with connections and disconnect after few minutes of unuse? What do you think?

Are these databases all in the same mongoDB, or are they to completely different instances? — Dan Crews, May 11 '18 at 15:16
@DanCrews Now it’s a single mongoDB. But in the future if project will grow fast, there will be several instances. — , May 11 '18 at 15:21

score 0 · Answer 1 · answered May 11 '18 at 15:29

Yeah, I would probably do something similar to what you're describing. I couldn't tell you if this code is fully functional, but here's a five-minute go at it:

class TimedConnection {
  constructor(uri) {
    this.uri = uri;
    this._connected = false;
    this.disconnect = this.disconnect.bind(this);
  }

  connect() {
    return new Promise((resolve, reject) => {
      if (!this._connected) {
        const db = this.db = mongoose.createConnection(this.uri);

        db.once('open', resolve());
        // whatever
      }

      clearTimeout(this._connectionTimeout);
      this._connectionTimeout = setTimeout(this.disconnect, 300000)

      return resolve(this.db);
    })
  }

  query() {
    this.connect().then((db) => {
      // something with `db`
    })
  }

  disconnect() {
    this.db.disconnect();
    this._connected = false;
  }
}

const connectionMap = {
  objectsDatabase: new TimedConnection('mongodb://whatever'),
  personsDatabase: new TimedConnection('mongodb://whateverthing'),
  ...
};

Thank you! Very nice solution. I will try it. But I have a small question: what purpose of “this.disconnect = this.disconnect.bind(this);” in constructor? — , May 11 '18 at 16:20
Because we're passing `this.disconnect` to the `setTimeout` function, the `this` keyword will lose its context, and the function won't work anymore. By doing a `.bind` in advance, that function gets pre-hardwired with the `this` parameter, so this doesn't happen. — Dan Crews, May 14 '18 at 19:12

Node.js and managing MongoDB databases

1 Answers1