Angular 4-从Http到HttpClient-对象类型上不存在属性'someproperty' [英] Angular 4 - Http to HttpClient - property 'someproperty' does not exist on type Object

问题描述

我正在尝试将现有应用程序从使用Http更改为使用HttpClient，但是我遇到了错误.

I am trying to change an existing app from using Http to using HttpClient, however i have an error.

因此，在我的服务中，您现在可以看到新代码与已注释掉的旧代码:

So in my service now you can see the new code vs the old code that's been commented out:

constructor(
        // private http: Http
        private http: HttpClient
    ) { }

    getSidebar() {
        // return this.http.get('http://localhost:3000/sidebar/edit-sidebar')
        //     .map(res => res.json());
        return this.http.get('http://localhost:3000/sidebar/edit-sidebar');
    }

在我的page.component.ts中，我有这个

this.sidebarService.getSidebar().subscribe(sidebar => {
                        this.sidebar = sidebar.content; // this does not work now
                    });

但是对于上面我评论过的那一行，我现在得到此错误:

However for the line above which I commented on I get this error now:

Property 'content'
 does not exist on type 'Object'.

但是，如果我console.log(sidebar)我得到以下信息:

However if I console.log(sidebar) I get the following:

{_id: "59dde326c7590a27a033fdec", content: "<h1>sidebar here</h1>"}

那是什么问题?

再次，Http有效，但HttpClient无效.

推荐答案

您可以使用接口，类等指定要返回的类型.例如，您可以使用类似以下的内容:

You can specify the type that is being returned, using an interface, class, etc. For example, you can use something like the following:

return this.http.get<Sidebar>('http://localhost:3000/sidebar/edit-sidebar');

例如，补充工具栏可以定义为:

As an example, Sidebar might be defined as:

interface Sidebar {
    _id: string;
    content: string;
}

请参阅Angular文档中的对响应进行类型检查，以了解更多信息:

See Typechecking the response from the Angular docs for further information:

... TypeScript会正确地抱怨从HTTP返回的对象没有results属性.这是因为，当HttpClient将JSON响应解析为一个对象时，它不知道该对象是什么形状.

...TypeScript would correctly complain that the Object coming back from HTTP does not have a results property. That's because while HttpClient parsed the JSON response into an Object, it doesn't know what shape that object is.

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