我有以下一段正确运行的代码。
<PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Release|AnyCPU' ">
<DebugType>pdbonly</DebugType>
<Optimize>true</Optimize>
<OutputPath>bin\Release\</OutputPath>
<DefineConstants>TRACE</DefineConstants>
<ErrorReport>prompt</ErrorReport>
<WarningLevel>4</WarningLevel>
<PlatformTarget>x64</PlatformTarget>
</PropertyGroup>
由于我可以重用部分代码，因此我想创建一个函数，但是现在遇到编译错误。我找不到错误所在。
新功能是
public createData(data:Data):Observable<any>{
console.log('contacting server at '+this.API_URL +this.NEW_DATA_URL +" with data "+data+ " with httpOptions "+httpOptions.withCredentials + ","+httpOptions.headers );
let newData = new Data(data)
let body = JSON.stringify(newQuestion);
//I WANT TO MOVE THE CODE BELOW INTO A FUNCTION BUT AM GETTING COMPILATION ERROR
this.loaderService.show();
return this.http.post(this.NEW_QUESTION_URL,body,httpOptions)
.pipe(tap(response => {
let httpEvent = <HttpEvent<any>>response;
if(httpEvent.type === HttpEventType.Response)
{
console.log('response from backend service:', response);
return result;
}
else {
console.log("not an http response")
return response;
}
})
,catchError(this.handleError)
,finalize(()=> this.loaderService.hide())); //error handler if Observable fails
}
ERROR是
private sendMessage(url:string, body:any,httpOptions:any){
this.loaderService.show();
return this.http.post(url,body,httpOptions)
.pipe(tap(response => {
let httpEvent = <HttpEvent<any>>response; //ERROR HERE - 'ArrayBuffer' cannot be converted to type 'HttpEvent<any>'.
if(httpEvent.type === HttpEventType.Response)
{
console.log('response from backend service:', response);
let result = <HttpResponse<any>>response;
return result;
}
else {
console.log("not an http response")
return response;
}
})
,catchError(this.handleError)
,finalize(()=> this.loaderService.hide())); //error handler if Observable fails
}
ERROR in src/app/web-to-backend-interface.service.ts(264,27): error TS2352:
Type 'ArrayBuffer' cannot be converted to type 'HttpEvent<any>'.
Type 'ArrayBuffer' is not comparable to type 'HttpUserEvent<any>'.
Property 'type' is missing in type 'ArrayBuffer'.有几个重载方法，其中一个返回Observable-angular.io/api/common/http/HttpClient#post。如何使Angular使用返回http.post的重载版本？我更改了代码并添加了Observable<T>，但这还是没有用
responseType:'json'我看到的错误是
const httpOptions = {
headers: new HttpHeaders({ 'Content-Type': 'application/json' }),
withCredentials: true,
observe: 'response' as 'response',
responseType: 'json'
};
let observable:Observable<HttpEvent<any>> = this.http.post(url,body,httpOptions)
return observable.pipe(tap((httpEvent:HttpEvent<any>) => {....}
为什么对工作代码进行单独的功能使其无法编译？我怎么了？
答案 0 :(得分：0)
虽然我不能回答为什么以前不出现错误，但是我可以建议您如何摆脱它（假设代码在重构之前已经正常工作）。如果在声明中为response提供类型，则不会获得必须尝试映射的假定类型：
.pipe(tap((response: HttpEvent<any>) => {
let httpEvent = response; // No need for type-casting here anymore.
答案 1 :(得分：0)
我能够解决它，但现在我所面临的问题比答案更多。如果有人可以向我解释这种行为，将不胜感激。
我正在使用以下httpOptions对象
const httpOptions = {
headers: new HttpHeaders({ 'Content-Type': 'application/json' }),
withCredentials: true,
observe: 'response' as 'response',
};
在代码的某些位置按如下方式使用它。
return this.http.post(this.SIGNUP_USER_URL,body,httpOptions)
这行得通。
然后，我想到将http.post更改为函数sendMessage（如问题所述），并仅在一次替换（请记住我在多个地方都使用this.http.post，想在一开始就尝试一下）。我注意到使用httpOptions会使post返回Observable<ArrayBuffer>。
疑问1-为什么？
然后我将httpOptions更改为
const httpOptions = {
headers: new HttpHeaders({ 'Content-Type': 'application/json' }),
withCredentials: true,
observe: 'response' as 'response',
responseType:'json'
};
在我直接使用http.post的地方（没有sendMessage的地方，开始出现错误。错误是
ERROR in src/app/web-to-backend-interface.service.ts(81,71): error TS2345: Argument of type '{ headers: HttpHeaders; withCredentials: boolean; observe: "response"; responseType: string; }' is not assignable to parameter of type '{ headers?: HttpHeaders | { [header: string]: string | string[]; }; observe?: "body"; params?: Ht...'.
Types of property 'observe' are incompatible.
Type '"response"' is not assignable to type '"body"'.
src/app/web-to-backend-interface.service.ts(112,52): error TS2345: Argument of type '{ headers: HttpHeaders; withCredentials: boolean; observe: "response"; responseType: string; }' is not assignable to parameter of type '{ headers?: HttpHeaders | { [header: string]: string | string[]; }; observe?: "body"; params?: Ht...'.
Types of property 'observe' are incompatible.
Type '"response"' is not assignable to type '"body"'.
src/app/web-to-backend-interface.service.ts(196,73): error TS2345: Argument of type '{ headers: HttpHeaders; withCredentials: boolean; observe: "response"; responseType: string; }' is not assignable to parameter of type '{ headers?: HttpHeaders | { [header: string]: string | string[]; }; observe?: "body"; params?: Ht...'.
src/app/web-to-backend-interface.service.ts(216,72): error TS2345: Argument of type '{ headers: HttpHeaders; withCredentials: boolean; observe: "response"; responseType: string; }' is not assignable to parameter of type '{ headers?: HttpHeaders | { [header: string]: string | string[]; }; observe?: "body"; params?: Ht...'.
src/app/web-to-backend-interface.service.ts(251,54): error TS2345: Argument of type '{ headers: HttpHeaders; withCredentials: boolean; observe: "response"; responseType: string; }' is not assignable to parameter of type '{ headers?: HttpHeaders | { [header: string]: string | string[]; }; observe?: "body"; params?: Ht...'.
src/app/web-to-backend-interface.service.ts(291,9): error TS2322: Type 'Observable<ArrayBuffer>' is not assignable to type 'Observable<HttpEvent<any>>'.
Type 'ArrayBuffer' is not assignable to type 'HttpEvent<any>'.
Type 'ArrayBuffer' is not assignable to type 'HttpUserEvent<any>'.
Property 'type' is missing in type 'ArrayBuffer'.
因此，我从responseType:'json'中删除了httpOptions，并在有效的this.http.post的{{1}}中添加了一个明确的对象！
sendMessage observe和responseType之间似乎存在关系。例如，observe = body和responseType = text表示帖子应观察（查看）正文，将其解释为文本并返回Observable。但是我不知道为什么我不能更改private sendMessage(url:string, body:any,httpOptions){
...
let observable:Observable<HttpEvent<any>> = this.http.post(url,body,{
headers: new HttpHeaders({ 'Content-Type': 'application/json' }),
withCredentials: true,
observe: 'events',
responseType: 'json'
})
...
}