如何从http.request()正确捕获异常?
我的部分代码:如何从http.request()正确捕获异常?,http,typescript,angular,observable,Http,Typescript,Angular,Observable,我的部分代码: myMethod()在浏览器控制台中产生异常: 原始异常:TypeError:this.http.request(…).map(…).catch不是函数 也许您可以尝试在导入中添加以下内容: import 'rxjs/add/operator/catch'; 您还可以执行以下操作: return this.http.request(request) .map(res => res.json()) .subscribe( data => consol
myMethod()
在浏览器控制台中产生异常:
原始异常:TypeError:this.http.request(…).map(…).catch不是函数
也许您可以尝试在导入中添加以下内容:
import 'rxjs/add/operator/catch';
您还可以执行以下操作:
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';
RxJS函数需要专门导入。一个简单的方法是从“rxjs/Rx”
然后确保访问
Observable
类作为Rx.Observable
新服务更新以使用HttpClientModule,并:
我使用.do()
()进行调试
当出现服务器错误时,我从正在使用的服务器(lite server)获取的响应
对象的主体
仅包含文本,因此我使用上面的err.text()
而不是err.json().error
。您可能需要为服务器调整该行
如果res.json()
由于无法解析json数据而引发错误,\u serverError
将不会获得响应
对象,因此需要检查instanceof
的原因
在这种情况下,将url
更改为/data/data.junk
以生成错误
任何一项服务的用户都应具有可处理错误的代码:
@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
);
}
}
@组件({
选择器:“我的应用程序”,
模板:'{data}}
{{errorMsg}}`
})
导出类AppComponent{
errorMsg:string;
构造函数(私有_myService:myService){}
恩戈尼尼特(){
这是。_myService.getData()
.订阅(
data=>this.data=data,
err=>this.errorMsg=err
);
}
}
在最新版本的angular4中使用
import { Observable } from 'rxjs/Rx'
它将导入所有必需的内容。有几种方法可以做到这一点。两者都很简单。每一个例子都非常有效。您可以将其复制到项目中并进行测试 第一种方法更可取,第二种方法有点过时,但到目前为止它也能工作 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
})
);
}
}
谢谢你的帮助,很有效。之后,我对
throw()
函数也有同样的问题。我添加了这一行import'rxjs/Rx'代码>取而代之。现在所有操作符都正常工作了。您是否模拟了一个错误以查看.catch
是否真的有效?.subscribe()
确实有效。是的,第二个问题是异常:TypeError:Observable\u 1.Observable.throw不是一个函数
。正如我前面所说的,它可以用@MattScarpino-answer或这个plunker中的maner来修复:也可以导入throw:import'rxjs/add/observable/throw'代码>并且不要导入所有内容,它太大了。很好的解决方案,,非常有用,我可能会添加(err)类型为ResponseRxjs是一个非常大的文件,如果你导入所有内容,它将增加你的加载时间如果你只需要一两个操作符,你不应该从Rxjs导入所有内容。不要这样做,它将导入所有RXJ,因此将导致捆绑包大小增加!
@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
);
}
}
import { Observable } from 'rxjs/Rx'
// 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
})
);
}
}
// 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);
}
);
}
}