Nested promoses, not waiting for the result - angular-promise

Question

I have a getProgrammeWrapper method that returns a promise. However in .then method i have few other promises that i will like to execute before returning the programmeWrapper[]
This is service.ts
I am calling the service in ngOnInit
this.service.getProgrammesByWrapper().then(((res) => {
this.programmes = res;
this.result.updateInfo("Sorting classes...")
this.programmes =this.programmes.sort((a,b) => {
return b.programme.click - a.programme.click;
});
this.result.updateSuccess(true);
}));
I hope i have explained the issue clearly. I have tried using await, but it doesn't work as expected.
getProgrammeWrapper()
getProgrammesByWrapper(): Promise<ProgrammeWrapper[]> {
var current = this;
var programmesDTO = new Array<ProgrammeWrapper>();
var table = this.client.getTable("programme");
return new Promise((resolve, reject) => {
table.read()
.then(function (modules) {
modules.forEach(element => {
var newProgDTO = new ProgrammeWrapper(element);
current.getLessonsByProgrammeId(element.id).then(lessons => newProgDTO.lesson = lessons).catch(err => console.log(err));
current.getUser(element.tutorId).then(user => newProgDTO.tutor = user).catch(err => console.log(err));
programmesDTO.push(newProgDTO)
});
resolve(programmesDTO)
}, function (error) { reject(error) });
});
}

Answer 1

I'm not sure it would work, could have bugs too. Try this:
getProgrammesByWrapper(): Promise<ProgrammeWrapper[]> {
var current = this;
var programmesDTO = new Array<ProgrammeWrapper>();
var table = this.client.getTable("programme");
return new Promise((resolve, reject) => {
table.read()
.then(function (modules) {
let promises = new Array<Promise<any>>();
modules.forEach(element => {
var newProgDTO = new ProgrammeWrapper(element);
let promise = current.getLessonsByProgrammeId(element.id)
.then(lessons => newProgDTO.lesson = lessons)
.catch(err => console.log(err));
promises.push(promise);
promise = current.getUser(element.tutorId)
.then(user => newProgDTO.tutor = user)
.catch(err => console.log(err));
promises.push(promise);
programmesDTO.push(newProgDTO)
});
// Wait for all promises to be ready before resolving
Promise.all(promises).then(function() {
resolve(programmesDTO);
});
}, function (error) { reject(error); });
});
}