Promise 解決在需要值時返回未定義

Question

當頁面加載時，我想獲取頁面狀態和登錄的員工，以便可以使用信息來根據給定的數據提取所有訂單。 問題是，無論我做什么，function: loadLoggedUser() 都太遲返回活躍員工。 我的“console.log()”功能目前在頁面加載時會出現這個 output：

resolve one: undefined 
resolve two: 3 
id when needed: undefined 
data: 1 

這是組件中的功能，我想要實現的所需順序是：loadLoggedUser() 然后 loadSelectedStatus() 然后一旦兩者都完成了 if 語句，就可以根據從其他兩個函數收集的信息來決定要觸發哪個 function。

export class OrdersComponent implements OnInit {
  activeUser = new Employee();

  constructor( public user: Employee ) {}

  ngOnInit(): void {
    this.initializePageData();
  }

  public initializePageData() {
    var self = this;
    this.loadLoggedUser()
      .then(function(resolve) {
        console.log(`resolve one: ${resolve}`);
        self.loadSelectedStatus()
          .then(function(resolve) {
            console.log(`resolve two: ${resolve}`);
            console.log(self.activeUser.id);
            if (self.selectedViewNumber == 2) {
              self.loadOrdersBySalesperson(self.activeUser.id);
            } else {
              if (self.selectedViewNumber == 3) { 
                self.loadOrdersByStatus(self.selectedStatus, 0);
              } else {
                self.loadOrdersByStatus(self.selectedStatus, self.activeUser.id);
              }
            }
          })
      });
  }

這些是 initizlizePageData() 中使用的函數的四個 function 定義：

  public async loadLoggedUsername() {
    return new Promise<string>((resolve, reject) => {
      var loggedUsername = this.employeeService.getLoggedUsername();
      resolve(loggedUsername);
    });
  }

  public async loadLoggedUser() {
    var self = this;
    this.loadLoggedUsername().then(function(res) {
      var loggedUsername = res;
      return new Promise<any>((resolve, reject) => {
        self.employeeService.getEmployeeByUsername(loggedUsername).subscribe(data => {
          self.activeUser = data;
          console.log(`data: ${data.id}`);
          resolve(data.id);
        });
      });
    });
  }

  public async loadSelectedStatus() {
    return new Promise<number>((resolve, reject) => {
      this.activatedRoute.queryParams.subscribe(params => {
        this.selectedStatus = params['status'];

        if (!this.selectedStatus) {
          this.selectedStatus = 3; 
        }
        resolve(this.selectedStatus);
      });
    });
  }

  public loadOrdersByStatus(selectedStatus: number, userId: number) {
    this.orderService.getOrdersByStatus(selectedStatus, userId).subscribe(res => {
      this.ordersArray = res;
    });
  }

  public loadOrdersBySalesperson(userId: number) {
    this.orderService.getOrdersBySalesperson(userId).subscribe(res => {
      this.ordersArray = res;
    });
  }
}

非常感謝任何輸入或反饋。

Answer 1

您的loadLoggedUser() function 中缺少return關鍵字。

更改聲明

this.loadLoggedUsername().then(function(res) { ... 

至

return this.loadLoggedUsername().then(function(res) { ...