从 ionic 4 中的 firebase 数据库中获取随机密钥

Question

我正在尝试获取将“课程”下的数据添加到 Firebase 时生成的随机密钥。我在我的应用程序中使用 ionic 4。

[1]https://imgur.com/a/mcN38Fz

在下面的代码中，在 onSubmit 函数中，最后两行： 我有一个变量保存用户的 UID，称为“currentUser”，另一个变量应该保存数据的键，添加了“datakey”。我不确定“dataKey”变量的完整代码应该是什么，以便我可以获得添加的数据的键。

有什么帮助吗？

import { Component, OnInit } from '@angular/core';
import { Router,ActivatedRoute } from '@angular/router';
import { Validators, FormBuilder, FormGroup, FormControl } from '@angular/forms';
import { FirebaseService } from '../services/firebase.service';
import { AuthService } from '../services/auth.service';

import { AngularFirestore } from '@angular/fire/firestore';
import * as firebase from 'firebase/app';

import { LoadingController } from '@ionic/angular';

@Component({
    selector: 'app-subjects',
    templateUrl: './subjects.page.html',
    styleUrls: ['./subjects.page.scss'],
})
export class SubjectsPage implements OnInit {

    subject_form: FormGroup;
    subjects: Array<any>;
    gradeArray: number[]=[];
    creditHourArray: number[]=[];
    creditHourTot: number=0;
    gpaDisplay: number;
    dataKey: string;


    constructor(
        private authService: AuthService,
        private formBuilder: FormBuilder,
        private firebaseService: FirebaseService,
        private router: Router,
        private route: ActivatedRoute,
        public loadingCtrl: LoadingController,
        public afs: AngularFirestore,

    ) { }
    ngOnInit() {
        if (this.route && this.route.data) {
            this.getData();
          }
          this.resetFields();

        }

        async getData(){
                this.route.data.subscribe(routeData => {
                  routeData['data'].subscribe(data => {
                    this.subjects = data;
                  })
                })
              }

              async presentLoading(loading) {
                return await loading.present();
              }

    resetFields() {
        this.subject_form = this.formBuilder.group({
            subName: new FormControl('', Validators.required),
            subCode: new FormControl('', Validators.required),
            creditHour: new FormControl('', Validators.required),
            grade: new FormControl('', Validators.required)
        });
    }

    onSubmit(value) {

        this.gradeArray.push(value.grade)
        this.creditHourArray.push(value.creditHour)
        let data = {
            subName: value.subName,
            subCode: value.subCode,
            creditHour: value.creditHour,
            grade: value.grade,
        }


        this.creditHourTot= this.creditHourTot + value.creditHour;




        this.firebaseService.createSubjects(data,this.gradeArray,this.creditHourArray)
        this.firebaseService.createGPA(this.gradeArray,this.creditHourArray)
        this.gpaDisplay = this.firebaseService.calGPA(this.gradeArray,this.creditHourArray)
        console.log(this.gpaDisplay);

        let currentUser = firebase.auth().currentUser
        let dataKey = this.afs.collection('people').doc(currentUser.uid).collection('Course')

    }

    goToSemPage() {
        this.router.navigate(["/semesters"]);
    }

    goToSubListPage(){
      this.router.navigate(["/subject-list"]);
    }


    logout() {
        this.authService.doLogout()
            .then(res => {
                this.router.navigate(["/home"]);
            }, err => {
                console.log(err);
            })
    }
}

这是我的方法“createSubjects”的代码

  createSubjects(value,gradeArray,creditHourArray) {
    return new Promise<any>((resolve, reject) => {

      let currentUser = firebase.auth().currentUser; 

      this.afs.collection('people').doc(currentUser.uid).collection('Course').add({
        subName: value.subName,
        subCode: value.subCode,
        creditHour: value.creditHour,
        grade: value.grade
        gpa: this.calGPA(gradeArray,creditHourArray)
      })

      .then(
          res => resolve(res),
          err => reject(err)
      )

    })
  }

更新：新的“onSubmit”方法：

onSubmit(value) {

        this.gradeArray.push(value.grade)
        this.creditHourArray.push(value.creditHour)
        let data = {
            subName: value.subName,
            subCode: value.subCode,
            creditHour: value.creditHour,
            grade: value.grade,
        }


        this.creditHourTot= this.creditHourTot + value.creditHour;

        this.firebaseService.createSubjects(data,this.gradeArray,this.creditHourArray).then(
            (val) => { this.datakey = val.id }
        );
        this.firebaseService.createGPA(this.gradeArray,this.creditHourArray)
        this.gpaDisplay = this.firebaseService.calGPA(this.gradeArray,this.creditHourArray)

        console.log(val);

        // let currentUser = firebase.auth().currentUser
        // let datakey = this.afs.collection('people').doc(currentUser.uid).collection('Course')

    }

Answer 1

我不完全确定我对您的用例的理解。

我假设您的方法“createSubjects”是您调用 firebase 以创建“课程”的方法。

所以你需要在你的方法“createSubject”中返回一个promise，

如果 createSubject 直接返回一个 firebase 承诺，那么您只需要：

this.firebaseService.createSubjects(data,this.gradeArray,this.creditHourArray).then(
    (val) => { this.datakey = val.id }
);

编辑：我将 'key' 更改为 'id' ，key 是您在 firebase 上获得的，在 firestore 上使用 'id'。