db.json explain line by line

get employees  (): Observable <any> {    // Method to fetch all employees data from the server

 get employees  (id: number):  Observable <any> {  // Method to fetch a specific employee's data using their id

add employees (employee: any): Observable <any> {  // Method to add a new employee

delete employees (id: number): Observable <any> {  // Method to delete an employee by their id

return this.http.get  (this.apiurl);   // Sends a GET request to the server (this.apiUrl) to fetch employee data

return this.http.get (`${this.apiUrl} /${id}`);  // Sends a GET request to retrieve data for a specific employee by their id

return this.http.Post ( this.apiurl, employee); 

• // Sends a POST request to add a new employee to the server
• // The 'employee' object is sent in the body of the request

return this.http. delete (`${this.apiUrl} /${id}`); // Sends a DELETE request to remove an employee based on their id from the server

Explanation:

1. getEmployees(): Observable<any>:

   • This method retrieves all employee data.
   • It sends an HTTP GET request to the server's base URL (this.apiUrl).

2. getEmployee(id: number): Observable<any>:

   • This method fetches data for a specific employee by their id.
   • It sends an HTTP GET request to the URL with the specific employee's id appended (e.g., /api/employees/1).

3. addEmployee(employee: any): Observable<any>:

   • This method adds a new employee by sending the employee data in the body of a POST request to the server.
   • The server then processes the request and adds the employee.

4. deleteEmployee(id: number): Observable<any>:

   • This method deletes a specific employee by their id.
   • It sends an HTTP DELETE request to the server, targeting the employee with the specified id.

Each method returns an Observable so that you can subscribe to these operations and handle them asynchronously.

    get employees ():void { // Method to fetch all employees from the server without returning anything

    get employees (id: number) :void { // Method to fetch a specific employee by id without returning anything

    add Employee (employees :any) :void {  // Method to add a new employee without returning anything

    delete Employee (id: number): void (  // Method to delete an employee by id without returning anything

this.employeeService.getEmployees().subscribe((data: any){

1. Subscribing to fetch and handle all employees.
2. 'data' contains the employee data returned from the server.
3.  You can now assign 'data' to a local variable or use it as needed, such as updating the table or UI.

this.employeeService.getEmployeess (id) sub (() => { 

1. Subscribing to fetch and handle a specific employee by id.
2. This executes once the specific employee data is retrieved by their 'id'.
3. You can now process the employee data or perform some action after it's fetched

this.employeeService.addEmployee(employee).subscribe(() => {

1. Subscribing to add a new employee.
2. This executes once the employee is successfully added.
3. You can now refresh the employee list or notify the user that the employee was added.

this .employeeService. deleteEmployee(id).subscribe(() => { 

1. Subscribing to delete an employee by id.
2. This executes after the employee is successfully deleted by their 'id'.
3. You can now update the UI, like removing the employee from a table or showing a success message

this.employees.data = data;

this.getEmployees();

this.getEmployees();

this.getEmployees();

this.getEmployees();