在Angular 5 http请求中使用observable有什么好处? [英] What is the benefit of using observable in Angular 5 http requests?

问题描述

我对在angular 5中使用httpclient感到困惑.我是angular的新手，只是遵循官方的angular教程.我对可观察对象，承诺，管道等不了解很多.目前我有一个用于处理所有http的服务对于发布请求，我正在使用pipe.下面是方法.

I am confused about using httpclient in angular 5.I am new to angular and just following the official angular tutorial.I dont know much about observables,promise,pipe etc..Currently I am having a service for handling all the http methods.For post request I am using with pipe.Below is the method.

create(model: any,URI) :Observable<Object>{
    return this.http.post(API_URL+URI, model)
    .pipe(
        catchError(this.handleError('create', model))
    );
}



private handleError<T> (operation = 'operation', result?: T) {
        return (error: any): Observable<T> => {

        console.error("default"+error); // log to console instead
        var errors=error["error"];

        var type=errors.errors;

        this.log(`${operation} failed: ${JSON.stringify(errors.errors)}`);

        return of(result as T);
        };
    }

      private log(message: string) {
        this.messageService.add('DataService: ' + message);
      }

在组件内部，我像这样调用此create方法.

And inside the component I am calling this create method like this..

onSubmit() { 
        this.loading = true;
        this._dataService.create(this.model,companytype_url).subscribe(data => {
            console.log("inside component data type-company"+JSON.stringify(data));
        },
        error=>{
            var error_data=JSON.stringify(error);
            console.log("inside component error type-company ->" + error_data)
        }
        );
        this.submitted = true;
        this.loading = false;
        this.companytypeForm.reset();
    }

我应该在组件中使用订阅吗?我需要一个通用的http类来处理所有api请求.这是一个很大的应用程序，并且有很多组件.由于我是Angular的新手，所以我对调用http方法的不同方法感到困惑.

Should I use subscribe in component? I need a general http class to handle the all the api requests.It is a big application and there are a lot of components.Since I am new to Angular I am confused about the different ways of calling http methods.

推荐答案

我应该在组件中使用订阅吗?

Should I use subscribe in component?

是的.如果您不订阅，则什么都不会发送到服务器

Yes. If you don't subscribe, nothing will be sent to the server

我需要一个通用的http类来处理所有api请求

I need a general http class to handle the all the api requests

这就是HttpClient.如果您的服务是完全通用的，它将不会在HttpClient已经提供的内容中添加任何内容.使用专用的服务，这些服务实际上提供了更高级别的抽象:具有类型化的参数，必要的输入转换，使用适当的URL，返回类型化的对象，知道如何转换响应等.

That's what HttpClient is. If your service is completely generic, it won't add anything to what HttpClient already provides. Use dedicated services, which actually provide a higher-level abstraction: have typed arguments, transform inputs necessary, use the appropriate URL, return typed objects, know how to transform the response, etc.

由于我是Angular的新手，所以我对调用http方法的不同方式感到困惑.

Since I am new to Angular I am confused about the different ways of calling http methods.

这就是Angular提供...文档的原因.例如，此 HttpClient指南，以及此

That's why Angular provides... documentation. For example, this HttpClient guide, and this RxJS guide. Read them.

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