Question

我遇到了从第二个请求返回Observable的问题。像这样：

commandRequest(action:string, commandData:any):Observable<CashDesckResponse>
{
    let command:CashDeskRequest;
    //ask my backend for command
    this.requestCommandString(action, commandData, "POST")
        //this is my response from backend
        .map(r=>r.response).subscribe(my_1_response=>{
        //then i need to send this response data to other server/action 
        //to execute it and return this second response as the result of
        //this method.
        command = new CashDesckRequest(my_1_response);
        return this.server.executeCommand(command).map(return_this=>return_this);
    }); 
};

private requestCommandString(action:string, requestData:any,
                             type:string):Observable<AjaxResponse>{
    return Observable.ajax({
        body:JSON.stringify(requestData),
        method:type,
        url:this._apiServerUrl+action
    }).map(r=>r);
};

我的问题是commandRequest从第一个.map（）返回值。如果我将尝试从内部订阅compiller throw错误返回值： [ts]声明类型既不是'void'也不是'any'的函数必须返回一个值。 https://habrastorage.org/web/93b/e6b/17b/93be6b17bf5b46b5847e67deefd6eea1.png

Answer 1

要从一个流映射到另一个流，您可以使用mergeMap或switchMap

commandRequest(action:string, commandData:any):Observable<CashDesckResponse>
{
    return this.requestCommandString(action, commandData, "POST")
        .map(r1 => new CashDesckRequest(r1.response)
        // map first response to command instance
        .mergeMap(command =>this.server.executeCommand(command));
        // map the command observable to a new observable
}

rxjs从第二个请求返回值

1 个答案: