错误类型错误：无法读取未定义的属性（读取“管道”）

Question

Why do I get an error (ERROR TypeError: Cannot read properties of undefined (reading 'pipe')) in this case when I add to the request "{ observe: 'response' }"? For to get all headers.

    let answer = this.http.post<ResponseLoginHttp>(AUTH_API + "login", json_data, { observe: 'response' });
let answer2
answer.subscribe(value => {
  this.dataService.setResponceLoginHttp(value.body);
  answer2 = value.body
})
return answer2.pipe(
  map((data) => {
    return data;

  }),
  catchError((error) => {
    console.log("Error - ", error);
    throw new Error(error.message);
  })
);}

In case I don't use "{ observe: 'response' }" Everything is fine:

    let answer = this.http.post<ResponseLoginHttp>(AUTH_API + "login", json_data );
answer.subscribe(value => {
  this.dataService.setResponceLoginHttp(value);
})
return answer.pipe(
  map((data) => {
    return data;

  }),
  catchError((error) => {
    console.log("Error - ", error);
    throw new Error(error.message);
  })
);}

how can i get all the headers from the response without having an error "ERROR TypeError: Cannot read properties of undefined (reading 'pipe')"?

Answer 1

this has nothing to do with your {observe: 'response'}

When you do this :

let answer = this.http.post<ResponseLoginHttp>(AUTH_API + "login", json_data, { observe: 'response' });
let answer2
answer.subscribe(value => {
  this.dataService.setResponceLoginHttp(value.body);
  answer2 = value.body
})
return answer2.pipe(

You call answer2 outside the subscribe and your answer2 is not yet defined. The subscribe is an async tool, js will not wait the response to execute the next lines. Plus your answer2 will never be an Observable .

You have to do something like this:

this.http.post<ResponseLoginHttp>(AUTH_API + "login", json_data, { observe: 'response' })
    .pipe(
        map((response: HttpResponse<ResponseLoginHttp>) => {
            // Here you can do something with response.headers
            return response.body;
        })      
     )
    .subscribe(
        value => this.dataService.setResponceLoginHttp(value),
        error => {
            console.log("Error - ", error);
            throw new Error(error.message);
        });

Or simpler:

this.http.post<ResponseLoginHttp>(AUTH_API + "login", json_data, { observe: 'response' })
    .subscribe(
        response => {
            // Here you can do something with response.headers
            this.dataService.setResponceLoginHttp(response.body);
        }),
        error => {
            console.log("Error - ", error);
            throw new Error(error.message);
        });