CODEWITHSUNDEEP
pouchdb
jtlindsey
jtlindsey

Reputation: 4863

Call method from pouchdb sync

I have a class setup like this

class FinanceDB {

  constructor() {
    this.PouchDB = require('pouchdb');
    this.db = new this.PouchDB('fin'); //8080
    this.remoteDB = new this.PouchDB('http://localhost:5984/rfin');

    this.db.sync(this.remoteDB, {
      live: true,
      retry: true
    }).on('change', function (change) {

      console.log('yo, something changed!');
      this.dosomething();

    }).on('error', function (err) {
      console.log("error", err);
      // yo, we got an error! (maybe the user went offline?)
    })
  };

  dosomething() {
    console.log('what now?');
  };
}

When the database changes, the console reads 'yo, something changed!' as expected. But my class method is never run and I don't get any errors. How do I call a method from inside pouchdb sync?

Upvotes: 0

Views: 219

Answers (1)

lossleader
lossleader

Reputation: 13495

With a function in the callback here:

on('change', function (change) {

  console.log('yo, something changed!');
  this.dosomething();

})

You are getting the dynamic this which is detached from your class in the callback.

In Es6, you can now just switch to an Arrow function to get 'this' to be lexically scoped:

on('change', (change) => {

  console.log('yo, something changed!');
  this.dosomething();

})

In the past, the usual method was to create a new variable set equal to this before setting up the callback:

var that = this;
...
on('change', function (change) {

  console.log('yo, something changed!');
  that.dosomething();

})

A comparison of the arrow and regular function in a JSfiddle here.

Upvotes: 1

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