类型“{HttpHeaders：typeof HttpHeaders；}”与类型“{Headers？：HttpHeaders；}”没有共同的属性

Question

嗨，我正在尝试类似CRUD操作，但它给出了'option'中的错误，我该如何解决。我写了下面的代码后，它给出了下面的错误。我使用了HttpClient和HttpHeaders，但也不起作用。

我编写了以下代码，用于使用API执行CRUD操作。

        import { Injectable } from '@angular/core';
            import { HttpClient } from '@angular/common/http';
            import { HttpHeaders } from '@angular/common/http';

            import { Observable } from 'rxjs';
            import { Employee } from './employee';


            @Injectable({
              providedIn: 'root'
            })
            export class EmployeeService {
              url = 'http://localhost:65389/api/EmaployeeMasters';
              constructor(private http: HttpClient) { }
              getAllEmployee(): Observable<Employee[]> {
                return this.http.get<Employee[]>(this.url);
              }

              getEmployeeById(employeeid: string): Observable<Employee> {
                return this.http.get<Employee>(this.url + '/' + employeeid);
              }
              createEmployee(employee: Employee): Observable<Employee> {
                const httpHeaders = new HttpHeaders().set('Content-Type', 'application/json');
                const options = {
                  httpHeaders: HttpHeaders
                };
                return this.http.post<Employee>(this.url, employee, options);
              }

              updateEmployee(employee: Employee): Observable<number> {
                const httpHeaders = new HttpHeaders().set('Content-Type', 'application/json');
                const options = {
                  httpHeaders: HttpHeaders
                };
                return this.http.post<number>(this.url + '/' + employee.ID, employee, options);
              }
              DeleteEmployeeById(employeeid: string): Observable<number> {
                const httpHeaders = new HttpHeaders()
                  .set('Content-Type', 'application/json');
                return this.http.delete<number>(this`enter code here`.url + '/' + employeeid);
              }
            }

Answer 1

我认为您的HttpHeaders有一些错误。尝试如下所示：

createEmployee(employee: Employee): Observable<Employee> {
  const httpOptions = { headers: new HttpHeaders({ 'Content-Type': 'application/json' }) };
  return this.http.post<Employee>(this.url, employee, httpOptions);
}

updateEmployee(employee: Employee): Observable<number> {
  const httpOptions = { headers: new HttpHeaders({ 'Content-Type': 'application/json' }) };
  return this.http.post<number>(this.url + '/' + employee.ID, employee, httpOptions);
}

此外，在deleteEmployeeByID函数上也有一些错误。也许是这样的：

deleteEmployeeById(employeeid: string): Observable<number> {
   const httpOptions = { headers: new HttpHeaders({ 'Content-Type': 'application/json' }) };
   return this.http.delete<number>(this.url + '/' + employee.ID, httpOptions);
}