this.transitionToRoute not working in my controller Ember - ember.js

Question

I am using a controller to read the value selected on a drop down menu, take in parameters of some input fields and then save the record. It creates the record and takes in the information just fine. My problem lies when I try to transition to another page at the end of the action. I keep getting the error: Cannot read property 'transitionToRoute' of undefined
I am completely stumped. Any ideas?
Here is my controller code:
var teamId;
export default Ember.Controller.extend({
auth: Ember.inject.service(),
actions: {
onSelectEntityType: function(value) {
console.log(value);
teamId = value;
return value;
},
createProcess: function(processName, processDescription) {
var currentID = this.get('auth').getCurrentUser();
let team = this.get('store').peekRecord('team', teamId);
let user = this.get('store').peekRecord('user', currentID);
let process = this.get('store').createRecord('process', {
team: team,
user: user,
name: processName,
description: processDescription
});
process.save().then(function () {
this.transitionToRoute('teams', teamId);
});
}
}
});
Here is the corresponding route:
export default Ember.Route.extend({
auth: Ember.inject.service(),
model: function() {
var currentID = this.get('auth').getCurrentUser();
return this.store.find('user', currentID);
}
});

Answer 1

You should have clear understanding about this keyword in Javascript. The keyword this only depends on how the function was called, not how/when/where it was defined.
function foo() {
console.log(this);
}
// normal function call
foo(); // `this` will refer to `window`
// as object method
var obj = {bar: foo};
obj.bar(); // `this` will refer to `obj`
// as constructor function
new foo(); // `this` will refer to an object that inherits from `foo.prototype`
Have a look at the MDN documentation to learn more.
You can cache the this in normal variable this and then access inside the call back.
var self = this;
process.save().then(function () {
self.transitionToRoute('teams', teamId);
});
ECMASCript 6 introduced arrow functions whose this is lexically scoped. Here, this is looked up in scope just like a normal variable.
process.save().then(() => {
this.transitionToRoute('teams', teamId);
});