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How to handle exceptions in REST API
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=> We will use below 2 annotation to handle exceptions in rest api

		1) @ExceptionHandler  (method level annotation)

		2) @RestControllerAdvice (class level annotation)

=> We can handle exceptions in 2 ways

	1) Class based Exception Handling

	2) Global Exception Handling

=> Class based exception handling means it will handle exceptions related to particular class only. 


```
@Data
public class ExInfo {

	private String exCode;

	private String exMsg;

	private LocalDateTime exDate;

}

```
@RestController
public class MsgRestController {

	@GetMapping("/welcome")
	public ResponseEntity<String> getWelcomeMsg() {

		String msg = "Welcome To Ashok IT";

		int i = 10 / 0;

		return new ResponseEntity<>(msg, HttpStatus.OK);
	}

	@ExceptionHandler(exception = Exception.class)
	public ResponseEntity<ExInfo> handleEx(Exception e) {

		ExInfo exInfo = new ExInfo();

		exInfo.setExCode("EX000002");
		exInfo.setExMsg(e.getMessage());
		exInfo.setExDate(LocalDateTime.now());

		return new ResponseEntity<>(exInfo, HttpStatus.INTERNAL_SERVER_ERROR);

	}

}

```

Note: If we write Exception Handler method inside rest controller then it is called as Class based exception Handling.

=> Global Exception handling means it will handle excetions related to all the classes available in the application.

Note: If we write Exception Handler method inside @RestControllerAdvice class then it is called as Global Exception handling.


```
public class UserNotFoundException extends RuntimeException {

	public UserNotFoundException(String msg) {
		super(msg);
	}

}

```
@RestControllerAdvice
public class AppExHandler {

	@ExceptionHandler(exception = UserNotFoundException.class)
	public ResponseEntity<ExInfo> handleUserNotFoundEx(UserNotFoundException e) {

		ExInfo exInfo = new ExInfo();

		exInfo.setExCode("EX000001");
		exInfo.setExMsg(e.getMessage());
		exInfo.setExDate(LocalDateTime.now());

		return new ResponseEntity<>(exInfo, HttpStatus.BAD_REQUEST);

	}

	@ExceptionHandler(exception = SQLException.class)
	public ResponseEntity<ExInfo> handleSQLEx(SQLException e) {

		ExInfo exInfo = new ExInfo();

		exInfo.setExCode("EX000003");
		exInfo.setExMsg(e.getMessage());
		exInfo.setExDate(LocalDateTime.now());

		return new ResponseEntity<>(exInfo, HttpStatus.INTERNAL_SERVER_ERROR);

	}

	@ExceptionHandler(exception = Exception.class)
	public ResponseEntity<ExInfo> handleEx(Exception e) {

		ExInfo exInfo = new ExInfo();

		exInfo.setExCode("EX000002");
		exInfo.setExMsg(e.getMessage());
		exInfo.setExDate(LocalDateTime.now());

		return new ResponseEntity<>(exInfo, HttpStatus.INTERNAL_SERVER_ERROR);

	}
}

```


========================================

1) application.properties vs application.yml

2) How to read properties from yml file into java class to remove hard coding

3) RestRepositories

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