从sqlite 4获取数据

Question

我的代码有一个问题，当我去寻找存储在SQLite中的数据时，这些数据会在最后被执行，而且我需要它们，因为我需要它们来使用最终将在屏幕上加载数据的服务。我把我的代码留在下面：

 import { Component, OnInit } from '@angular/core';
 import { LoadingController, Platform } from '@ionic/angular';
 import { AndroidPermissions } from '@ionic-native/android-permissions/ngx';
 import { Uid } from '@ionic-native/uid/ngx';
 import { EsqueletoServiceProvider } from '../../providers/no4get- 
 service/no4get-services';
 import { DatabaseServiceProvider } from '../../providers/database- 
 service/database-service';
 import { AlertController } from '@ionic/angular';

 @Component({
   selector: 'app-general',
   templateUrl: './general.page.html',
   styleUrls: ['./general.page.scss'],
 })
 export class GeneralPage {
   listaCategorias: any;
   token: any;
   imei: string;
   cards: any;
   loading: any;
   datosTelefono: any;


   constructor(private loadingController: LoadingController,
     public esqueletoService: EsqueletoServiceProvider,
     public databaseService: DatabaseServiceProvider,
     public uid: Uid, 
     public androidPermissions: AndroidPermissions,
     public alertCtrl: AlertController,
     public platform: Platform
     ) 
   { 
     this.listaCategorias = "1";
     this.databaseService.getSesion(1).then(result => {
       this.token = result.valor;
     })
     .catch( error => {
       this.MostrarAlerta("Noticias","","Hubo un problema al obtener los 
       datos del usuario.");
     });

     this.databaseService.getSesion(2).then(result => {
       this.imei = result.valor;
     })
     .catch( error => {
       this.MostrarAlerta("Noticias","","Hubo un problema al obtener los 
       datos del usuario.");
     });
   }



 ionViewDidEnter()
   {
     this.platform.ready().then(() => { 
       let datos = { 
         idNoticias: 0, 
         token: this.token,
         imei: this.imei
       };

       this.LoaderNoticias();
       this.esqueletoService.CargarNoticiasGeneral(datos).then((result) => 
       {
         if (result != null) 
         {
           let codigoError = result.toString().split('|');

           if(codigoError[0] == "777")
           {
             this.loadingController.dismiss();
             this.cards = result;
           }
           else if (codigoError[0] == "305")
           {
             this.loadingController.dismiss();
             this.MostrarAlerta("Noticias","",codigoError[2]);
           }
           else if (codigoError[0] == "310")
           {
             this.loadingController.dismiss();
             this.MostrarAlerta("Noticias","",codigoError[2]);
           }
           else if(codigoError[0] == "315")
           {
             this.loadingController.dismiss();
             this.MostrarAlerta("Noticias","",codigoError[2]);
           }
           else if(codigoError[0] == "000")
           {
             this.loadingController.dismiss();
             this.MostrarAlerta("Noticias","","Estimado usuario, hubo un 
             error inesperado.");
           }   
         } else {
           this.loadingController.dismiss();
           this.MostrarAlerta("Noticias","","Estimado usuario, hubo un 
           error inesperado.");
         }
       }, (err) => {
         this.loadingController.dismiss();
         this.MostrarAlerta("Noticias","","Estimado usuario, hubo un error 
         inesperado.");
       });
     });
   }

当前，当执行ionViewDidEnter ()事件时，它会创建一个名为data的变量，这是我想要向服务发送数组的地方，但到那时为止，令牌和IMEI字段都是undefined。通过在整个ionViewDidEnter ()事件执行后遵循代码的路径，代码只分配构造函数中的令牌和IMEI变量的数据。问题是，如何在执行ionViewDidEnter ()事件之前获得这些数据？

我的代码是在visual代码和Ionic 4中执行的。在我继续调查的同时，我提前感谢您给我的所有可能的帮助。

Answer 1

如果您的数据依赖于其他异步数据，那么您只需继续嵌套它，直到您慢慢变得疯狂：

从构造函数中删除代码，然后将其全部放入ionViewDidEnter()中，并进行嵌套：

ionViewDidEnter() {
    this.platform.ready().then(() => {
        this.listaCategorias = "1";
        this.databaseService.getSesion(1).then(result => {
            this.token = result.valor;

            this.databaseService.getSesion(2).then(result => {
                this.imei = result.valor;

                let datos = {
                    idNoticias: 0,
                    token: this.token,
                    imei: this.imei
                };

                this.LoaderNoticias();
                this.esqueletoService.CargarNoticiasGeneral(datos).then((result) => {
                    if (result != null) {
                        let codigoError = result.toString().split('|');

                        if (codigoError[0] == "777") {
                            this.loadingController.dismiss();
                            this.cards = result;
                        }
                        else if (codigoError[0] == "305") {
                            this.loadingController.dismiss();
                            this.MostrarAlerta("Noticias", "", codigoError[2]);
                        }
                        else if (codigoError[0] == "310") {
                            this.loadingController.dismiss();
                            this.MostrarAlerta("Noticias", "", codigoError[2]);
                        }
                        else if (codigoError[0] == "315") {
                            this.loadingController.dismiss();
                            this.MostrarAlerta("Noticias", "", codigoError[2]);
                        }
                        else if (codigoError[0] == "000") {
                            this.loadingController.dismiss();
                            this.MostrarAlerta("Noticias", "", "Estimado usuario, hubo un error inesperado.");
                        }
                    } else {
                        this.loadingController.dismiss();
                        this.MostrarAlerta("Noticias", "", "Estimado usuario, hubo un error inesperado.");
                    }
                }, (err) => {
                    this.loadingController.dismiss();
                    this.MostrarAlerta("Noticias", "", "Estimado usuario, hubo un error inesperado.");
                });
            }).catch(error => {
                this.MostrarAlerta("Noticias", "", "Hubo un problema al obtener los datos del usuario.");
            });
        }).catch(error => {
            this.MostrarAlerta("Noticias", "", "Hubo un problema al obtener los datos del usuario.");
        });
    });
}