如何正确赶上例外，从http.request（）？
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我的代码部分：
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()在浏览器的控制台产生异常：
原始异常：类型错误：。this.http.request（...）地图（...）美中不足的是不是一个函数
答案
或许你可以尝试在进口增加这样的：
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')
);
每评论：
EXCEPTION: TypeError: Observable_1.Observable.throw is not a function
同样，对于这一点，你可以使用：
import 'rxjs/add/observable/throw';
另一答案
新服更新为使用HttpClientModule和RxJS v5.5.x：
import { Injectable } from '@angular/core';
import { HttpClient, HttpErrorResponse } from '@angular/common/http';
import { Observable } from 'rxjs/Observable';
import { catchError, tap } from 'rxjs/operators';
import { SomeClassOrInterface} from './interfaces';
import 'rxjs/add/observable/throw';
@Injectable()
export class MyService {
url = 'http://my_url';
constructor(private _http:HttpClient) {}
private handleError(operation: String) {
return (err: any) => {
let errMsg = `error in ${operation}() retrieving ${this.url}`;
console.log(`${errMsg}:`, err)
if(err instanceof HttpErrorResponse) {
// you could extract more info about the error if you want, e.g.:
console.log(`status: ${err.status}, ${err.statusText}`);
// errMsg = ...
}
return Observable.throw(errMsg);
}
}
// public API
public getData() : Observable<SomeClassOrInterface> {
// HttpClient.get() returns the body of the response as an untyped JSON object.
// We specify the type as SomeClassOrInterfaceto get a typed result.
return this._http.get<SomeClassOrInterface>(this.url)
.pipe(
tap(data => console.log('server data:', data)),
catchError(this.handleError('getData'))
);
}
老服务，使用的是弃用的HttpModule：
import {Injectable} from 'angular2/core';
import {Http, Response, Request} from 'angular2/http';
import {Observable} from 'rxjs/Observable';
import 'rxjs/add/observable/throw';
//import 'rxjs/Rx'; // use this line if you want to be lazy, otherwise:
import 'rxjs/add/operator/map';
import 'rxjs/add/operator/do'; // debug
import 'rxjs/add/operator/catch';
@Injectable()
export class MyService {
constructor(private _http:Http) {}
private _serverError(err: any) {
console.log('sever error:', err); // debug
if(err instanceof Response) {
return Observable.throw(err.json().error || 'backend server error');
// if you're using lite-server, use the following line
// instead of the line above:
//return Observable.throw(err.text() || 'backend server error');
}
return Observable.throw(err || 'backend server error');
}
private _request = new Request({
method: "GET",
// change url to "./data/data.junk" to generate an error
url: "./data/data.json"
});
// public API
public getData() {
return this._http.request(this._request)
// modify file data.json to contain invalid JSON to have .json() raise an error
.map(res => res.json()) // could raise an error if invalid JSON
.do(data => console.log('server data:', data)) // debug
.catch(this._serverError);
}
}
我用.do()（now .tap()）进行调试。
当有一个服务器错误，body对象，我从我使用（精简版服务器）服务器获得的Response只包含文本，所以我用err.text()上面，而不是err.json().error的原因。您可能需要调整该行对您的服务器。
如果res.json()引发一个错误，因为它无法解析JSON数据，_serverError不会得到一个Response对象，因此对于instanceof检查的原因。
在这种plunker，改变url以./data/data.junk产生错误。
任一服务的用户应具有的代码，可以处理错误：
@Component({
selector: 'my-app',
template: '<div>{{data}}</div>
<div>{{errorMsg}}</div>`
})
export class AppComponent {
errorMsg: string;
constructor(private _myService: MyService ) {}
ngOnInit() {
this._myService.getData()
.subscribe(
data => this.data = data,
err => this.errorMsg = <any>err
);
}
}
另一答案
有几种方法可以做到这一点。两者都非常简单。每个实例的伟大工程。你可以把它复制到你的项目并对其进行测试。
第一种方法是优选的，第二个是有点过时，但到目前为止，它也能工作。
1）溶液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.它是旧的方式，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) => {
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