等待来自承诺的响应以填充表单

Question

您好，我正在开发一个角度/打字稿应用程序，我已经阅读了有关promise的信息，但我不清楚您的帮助。

有函数getUserById()返回用户信息，getAttributeByUserId()，所以我需要从两个函数中填写表单，但getAttribute上的变量undefinied，这是我的代码。

角度/打字稿

getUserById(userId, modalContent) {
  console.log('get user by id ' + userId);
  const config = AppConfiguration.CONFIG_GET_USERS_BY_ID;
  config.user_id = userId;
  const date = new Date();
  this._httpService.CountUsers().post(config).subscribe((data: any) => {
    console.log('resultado al obtener usuario editado ' + data[0].user_id);
    this.userForm.patchValue({'firstName': data[0].firstname});
    this.userForm.patchValue({'secondName': data[0].secondname});
    this.userForm.patchValue({'lastName': data[0].lastname});
    this.userForm.patchValue({'mothersLastName': data[0].motherslastname});
    this.userForm.patchValue({'birthDay': {
      date: {
        year: data[0].birthday.substring(0, 4),
        month: data[0].birthday.substring(5, 7),
        day: data[0].birthday.substring(8, 10)}
    }});
    this.userForm.patchValue({'roleId': data[0].role_id});
    this.userForm.patchValue({'email': data[0].email});
    this.userForm.patchValue({'userId': data[0].user_id});
    this.open(modalContent);
    // this.open(modalContent);
  });
}
getAttributeByUserId(userId: number) {
  const config = AppConfiguration.CONFIG_GET_ATTRIBUTE_BY_ID;
  config.user_id = userId;
  this._httpService.CountUsers().post(config).subscribe((data: any) => {
    this.attributes = data;
  });
}

我需要在getUserById内部调用getAttributeByUserId并获取数据。

Answer 1

看到你的答案后，你问的是什么就更清楚了。您需要返回一个可以从 getAttributeByUserId 订阅的可观察量。如果您仍想将返回的值推送到attributes那么您可以使用 tap 在该方法中执行此操作，这允许您在执行订阅回调之前执行代码而不更改返回的结果，或者您可以让调用方在subscribe回调中处理这个问题。我选择了前者。

在学习如何使用打字稿/角度进行开发时，另一个关键建议是：学习使用强类型。这可以节省以后更难调试或捕获的运行时错误。我推断下面有一些名为Attribute的接口或类，如果你还没有，我建议使用接口(从http调用返回的数据结构的常见做法(。

import { Observable } from 'rxjs';
import { tap } from 'rxjs/operators';

getUserById(userId, modalContent) {
  console.log('get user by id ' + userId);
  const config = AppConfiguration.CONFIG_GET_USERS_BY_ID;
  config.user_id = userId;
  const date = new Date();
  this._httpService.CountUsers().post(config).subscribe((data: any) => {
    console.log('resultado al obtener usuario editado ' + data[0].user_id);
    this.userForm.patchValue({'firstName': data[0].firstname});
    this.userForm.patchValue({'secondName': data[0].secondname});
    this.userForm.patchValue({'lastName': data[0].lastname});
    this.userForm.patchValue({'mothersLastName': data[0].motherslastname});
    this.userForm.patchValue({'birthDay': {
      date: {
        year: data[0].birthday.substring(0, 4),
        month: data[0].birthday.substring(5, 7),
        day: data[0].birthday.substring(8, 10)}
    }});
    this.userForm.patchValue({'roleId': data[0].role_id});
    this.userForm.patchValue({'email': data[0].email});
    this.userForm.patchValue({'userId': data[0].user_id});
    this.getAttributeByUserId(userId).subscribe((attributes) => {
      this.open(modalContent);
    });
  });
}
getAttributeByUserId(userId: number) : Observable<Attribute[]> {
  const config = AppConfiguration.CONFIG_GET_ATTRIBUTE_BY_ID;
  config.user_id = userId;
  return this._httpService.CountUsers().post<Attribute[]>(config).pipe(tap((data) => {
    this.attributes = data;
  }));
}

Answer 2

我更改了函数

getUserById(userId, modalContent) {
console.log('get user by id ' + userId);
const config = AppConfiguration.CONFIG_GET_USERS_BY_ID;
config.user_id = userId;
const date = new Date();
this._httpService.CountUsers().post(config).subscribe((data: any) => {
  console.log('resultado al obtener usuario editado ' + data[0].user_id);
  this.userForm.patchValue({'firstName': data[0].firstname});
  this.userForm.patchValue({'secondName': data[0].secondname});
  this.userForm.patchValue({'lastName': data[0].lastname});
  this.userForm.patchValue({'mothersLastName': data[0].motherslastname});
  this.userForm.patchValue({'birthDay': {
    date: {
        year: data[0].birthday.substring(0, 4),
        month: data[0].birthday.substring(5, 7),
        day: data[0].birthday.substring(8, 10)}
    }});
  this.userForm.patchValue({'roleId': data[0].role_id});
  this.userForm.patchValue({'email': data[0].email});
  this.userForm.patchValue({'userId': data[0].user_id});
  this.getAttributeByUserId(data[0].user_id).then((response) => {
    console.log('respueta del ws attribuete' + JSON.stringify(response));
    this.open(modalContent);
  });
  // this.open(modalContent);
});

}

getAttributeByUserId(userId: number) {
const config = AppConfiguration.CONFIG_GET_ATTRIBUTE_BY_ID;
config.user_id = userId;
this._httpService.CountUsers().post(config).subscribe((data: any) => {
  this.attributes = data;
});
return Promise.resolve(this.attributes);

}