如何从 http.request() 中正确捕获异常？

Question

我的部分代码：

 import {Injectable} from 'angular2/core';
import {Http, Headers, Request, Response} from 'angular2/http';
import {Observable} from 'rxjs/Observable';
import 'rxjs/add/operator/map';

@Injectable()
export class myClass {

  constructor(protected http: Http) {}

  public myMethod() {
    let request = new Request({
      method: "GET",
      url: "http://my_url"
    });

    return this.http.request(request)
      .map(res => res.json())
      .catch(this.handleError); // Trouble line.
                                // Without this line code works perfectly.
  }

  public handleError(error: Response) {
    console.error(error);
    return Observable.throw(error.json().error || 'Server error');
  }

}

myMethod() 在浏览器的控制台中产生异常：

原始异常：TypeError：this.http.request(…).map(…).catch 不是函数

原文由 Nick 发布，翻译遵循 CC BY-SA 4.0 许可协议

Answer 1

也许您可以尝试在导入中添加它：

 import 'rxjs/add/operator/catch';

你也可以这样做：

 return this.http.request(request)
  .map(res => res.json())
  .subscribe(
    data => console.log(data),
    err => console.log(err),
    () => console.log('yay')
  );

---

根据评论：

例外：TypeError：Observable_1.Observable.throw 不是函数

同样，为此，您可以使用：

 import 'rxjs/add/observable/throw';

原文由 acdcjunior 发布，翻译遵循 CC BY-SA 3.0 许可协议

Answer 2

有几种方法可以做到这一点。两者都非常简单。每个例子都很好用。您可以将其复制到您的项目中并进行测试。

第一种方法更可取，第二种方法有点过时，但到目前为止它也有效。

1）解决方案1

 // File - app.module.ts
import { BrowserModule } from '@angular/platform-browser';
import { NgModule } from '@angular/core';
import { HttpClientModule } from '@angular/common/http';

import { AppComponent } from './app.component';
import { ProductService } from './product.service';
import { ProductModule } from './product.module';

@NgModule({
  declarations: [
    AppComponent
  ],
  imports: [
    BrowserModule,
    HttpClientModule
  ],
  providers: [ProductService, ProductModule],
  bootstrap: [AppComponent]
})
export class AppModule { }

// File - product.service.ts
import { Injectable } from '@angular/core';
import { HttpClient } from '@angular/common/http';

// Importing rxjs
import 'rxjs/Rx';
import { Observable } from 'rxjs/Rx';
import { catchError, tap } from 'rxjs/operators'; // Important! Be sure to connect operators

// There may be your any object. For example, we will have a product object
import { ProductModule } from './product.module';

@Injectable()
export class ProductService{
    // Initialize the properties.
    constructor(private http: HttpClient, private product: ProductModule){}

    // If there are no errors, then the object will be returned with the product data.
    // And if there are errors, we will get into catchError and catch them.
    getProducts(): Observable<ProductModule[]>{
        const url = 'YOUR URL HERE';
        return this.http.get<ProductModule[]>(url).pipe(
            tap((data: any) => {
                console.log(data);
            }),
            catchError((err) => {
                throw 'Error in source. Details: ' + err; // Use console.log(err) for detail
            })
        );
    }
}

2）解决方案2。这是旧方法，但仍然有效。

 // File - app.module.ts
import { BrowserModule } from '@angular/platform-browser';
import { NgModule } from '@angular/core';
import { HttpModule } from '@angular/http';

import { AppComponent } from './app.component';
import { ProductService } from './product.service';
import { ProductModule } from './product.module';

@NgModule({
  declarations: [
    AppComponent
  ],
  imports: [
    BrowserModule,
    HttpModule
  ],
  providers: [ProductService, ProductModule],
  bootstrap: [AppComponent]
})
export class AppModule { }

// File - product.service.ts
import { Injectable } from '@angular/core';
import { Http, Response } from '@angular/http';

// Importing rxjs
import 'rxjs/Rx';
import { Observable } from 'rxjs/Rx';

@Injectable()
export class ProductService{
    // Initialize the properties.
    constructor(private http: Http){}

    // If there are no errors, then the object will be returned with the product data.
    // And if there are errors, we will to into catch section and catch error.
    getProducts(){
        const url = '';
        return this.http.get(url).map(
            (response: Response) => {
                const data = response.json();
                console.log(data);
                return data;
            }
        ).catch(
            (error: Response) => {
                console.log(error);
                return Observable.throw(error);
            }
        );
    }
}

原文由 Victor Isaikin 发布，翻译遵循 CC BY-SA 4.0 许可协议