RAMSIS-CODE: Exception Handling and Validation in Spring Boot

Handling exceptions is an important part of building a robust application. This tutorial I will illustrate how to implement Exception Handling and Validation with Spring for a REST API
please follow the steps and download the code below.

-------------------------------- UserController -------------------------------------------

package com.ramsis.restApi.controller;

import java.util.List;
import javax.validation.Valid;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.http.HttpStatus;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.DeleteMapping;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.PutMapping;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
import com.ramsis.restApi.payloads.ApiResponse;
import com.ramsis.restApi.payloads.UserDto;
import com.ramsis.restApi.services.UserService;

@RestController
@RequestMapping("/api/users")
public class UserController {
@Autowired
private UserService userService;

@PostMapping("/")
public ResponseEntity<UserDto>addUser(@Valid @RequestBody UserDto userDto)
{
UserDto createUser=this.userService.createuser(userDto);
return new ResponseEntity<>(createUser,HttpStatus.CREATED);
}

@PutMapping("/{userId}")
public ResponseEntity<UserDto> updateUser(@Valid @RequestBody UserDto userDto , @PathVariable("userId") Integer userId){

UserDto updateUser=this.userService.updateUser(userDto, userId);
return ResponseEntity.ok(updateUser);
}

@DeleteMapping("/{userId}")
public ResponseEntity<ApiResponse>deletedUser(@PathVariable("userId") Integer userId)
{
this.userService.deleteUser(userId);
return new ResponseEntity<ApiResponse>(new ApiResponse("user delete succsfully",String.valueOf(HttpStatus.OK.value()),true),HttpStatus.OK);

}
@GetMapping("/")
public ResponseEntity<List<UserDto>> getAllUsers()
{
return ResponseEntity.ok(this.userService.getAllUsers());
}

@GetMapping("/{userId}")
public ResponseEntity<UserDto> getAllUsers(@PathVariable("userId") Integer userId)
{
return ResponseEntity.ok(this.userService.getByuserId(userId));
}

}

--------------------------------- GlobelExceptionHandler --------------------------------

package com.ramsis.restApi.exception;

import java.util.HashMap;

import java.util.Map;

import org.springframework.http.HttpStatus;

import org.springframework.http.ResponseEntity;

import org.springframework.validation.FieldError;

import org.springframework.web.bind.MethodArgumentNotValidException;

import org.springframework.web.bind.annotation.ExceptionHandler;

import org.springframework.web.bind.annotation.RestControllerAdvice;

import com.ramsis.restApi.payloads.ApiResponse;

@RestControllerAdvice

public class GlobelExceptionHandler {

@ExceptionHandler(ResourcesNotoundExcpetion.class)

public ResponseEntity<ApiResponse> resourceNotfoiunexceptionHandler(ResourcesNotoundExcpetion ex)

{

String message=ex.getMessage();

ApiResponse apiResponse=new ApiResponse(message,String.valueOf(HttpStatus.NOT_FOUND.value()),false);

return new ResponseEntity<ApiResponse>(apiResponse,HttpStatus.NOT_FOUND);

}

@ExceptionHandler(MethodArgumentNotValidException.class)

public ResponseEntity<Map<String, String>> handleMethodArgsNotValidateExpection(MethodArgumentNotValidException ex)

{

Map<String, String> resp=new HashMap<>();

ex.getBindingResult().getAllErrors().forEach(error->{

String filedName=((FieldError)error).getField();

String messsage=error.getDefaultMessage();

resp.put(filedName, messsage);

});

return new ResponseEntity<Map<String,String>>(resp,HttpStatus.BAD_REQUEST);

}

@ExceptionHandler(ApiException.class)

public ResponseEntity<ApiResponse> handleApiException(ApiException ex)

{

String message=ex.getMessage();

ApiResponse apiResponse=new ApiResponse(message,String.valueOf(HttpStatus.BAD_REQUEST.value()),true);

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

}

----------------------------------- ResourcesNotoundExcpetion -----------------------------------

package com.ramsis.restApi.exception;

import lombok.Getter;

import lombok.Setter;

@Getter

@Setter

public class ResourcesNotoundExcpetion extends RuntimeException{

String resourceName;

String feildName;

long feildValue;

public ResourcesNotoundExcpetion(String resourceName, String feildName, long feildValue) {

super(String.format("%s not found with his name %s :%s", resourceName,feildName,feildValue));

this.resourceName = resourceName;

this.feildName = feildName;

this.feildValue = feildValue;

}

------------------------ ApiResponse--------------------------

package com.ramsis.restApi.payloads;

import lombok.AllArgsConstructor;

import lombok.Getter;

import lombok.NoArgsConstructor;

import lombok.Setter;

@Getter

@Setter

@NoArgsConstructor

@AllArgsConstructor

public class ApiResponse {

private String meaassge;

private String status;

private boolean success;

}

--------------------------- userDto --------------------------------

package com.ramsis.restApi.payloads;

import javax.validation.constraints.Email;

import javax.validation.constraints.NotEmpty;

import javax.validation.constraints.Pattern;

import javax.validation.constraints.Size;

import lombok.Getter;

import lombok.NoArgsConstructor;

import lombok.Setter;

@NoArgsConstructor

@Setter

@Getter

public class UserDto {

private int userId;

@NotEmpty

@Size(min = 4,message ="username must be minimum 4 character")

private String name;

@Email(message = "your email id wrong")

private String email;

@NotEmpty

//@Size(min = 3,max = 15, message = "password must be minimum 3 and max 12 character")

@Pattern(regexp = "^(?=.*[0-9])(?=.*[a-z])(?=.*[A-Z])(?=.*[!@#&()–[{}]:;',?/*~$^+=<>]).{5,15}$", message = ""

+ "Password must contain at least one digit [0-9]."

+ "Password must contain at least one lowercase Latin character [a-z]."

+ "Password must contain at least one uppercase Latin character [A-Z]."

+ "Password must contain at least one special character like ! @ # & ( )."

+ "Password must contain a length of at least 5 characters and a maximum of 15 characters.")

private String password;

private String region;

@Size(min = 2,message ="department must be minimum 2 character")

private String department;

}

--------------------------------- userRepository ------------------------------------

package com.ramsis.restApi.repository;

import java.util.Optional;

import org.springframework.data.jpa.repository.JpaRepository;

import com.ramsis.restApi.entities.User;

public interface UserRepository extends JpaRepository<User, Integer>{

Optional<User> findByEmail(String email);

}

---------------------------- userService --------------------------

package com.ramsis.restApi.services;

import java.util.List;

import com.ramsis.restApi.payloads.UserDto;

public interface UserService {

UserDto registerNewUser(UserDto user);

UserDto createuser(UserDto user);

UserDto updateUser(UserDto user, Integer userId);

UserDto getByuserId(Integer userId);

List<UserDto> getAllUsers();

void deleteUser(Integer userId);

}

--------------------------- userServiceImpl --------------------

package com.ramsis.restApi.services;

import java.util.List;

import java.util.stream.Collectors;

import org.modelmapper.ModelMapper;

import org.springframework.beans.factory.annotation.Autowired;

import org.springframework.stereotype.Service;

import com.ramsis.restApi.entities.User;

import com.ramsis.restApi.exception.ResourcesNotoundExcpetion;

import com.ramsis.restApi.payloads.UserDto;

import com.ramsis.restApi.repository.UserRepository;

@Service

public class UserServiceImpl implements UserService{

@Autowired

private ModelMapper mapper;

@Autowired

private UserRepository userRepository;

@Override

public UserDto createuser(UserDto userDto) {

User user=this.dtoToUser(userDto);

User saveUsers=this.userRepository.save(user);

return this.userToDto(saveUsers);

}

@Override

public UserDto updateUser(UserDto userDto, Integer userId) {

User user=this.userRepository.findById(userId)

.orElseThrow(()-> new ResourcesNotoundExcpetion("User","Id",userId));

user.setName(userDto.getName());

user.setEmail(userDto.getEmail());

user.setPassword(userDto.getPassword());

user.setRegion(userDto.getRegion());

user.setDepartment(userDto.getDepartment());

User updateUser=this.userRepository.save(user);

UserDto userDto1= this.userToDto(updateUser);

return userDto1;

}

@Override

public UserDto getByuserId(Integer userId) {

User user=this.userRepository.findById(userId)

.orElseThrow(()-> new ResourcesNotoundExcpetion("User","Id",userId));

return this.userToDto(user);

}

@Override

public List<UserDto> getAllUsers() {

List<User> users=this.userRepository.findAll();

List<UserDto> userDtos=users.stream().map(user->this.userToDto(user)).collect(Collectors.toList());

return userDtos;

}

@Override

public void deleteUser(Integer userId) {

User user =this.userRepository.findById(userId).orElseThrow(()-> new ResourcesNotoundExcpetion("User","Id",userId));

this.userRepository.delete(user);

}

@Override

public UserDto registerNewUser(UserDto userDto) {

User user = this.mapper.map(userDto, User.class);

//endoed the password

user.setPassword(user.getPassword());

User newUser=this.userRepository.save(user);

return this.mapper.map(newUser, UserDto.class);

}

private User dtoToUser(UserDto userDto)

{

User user=this.mapper.map(userDto, User.class);

// user.setUserId(userDto.getUserId());

// user.setName(userDto.getName());

// user.setEmail(userDto.getEmail());

// user.setDepartment(userDto.getDepartment());

// user.setPassword(userDto.getPassword());

// user.setRegion(userDto.getRegion());

return user;

}

public UserDto userToDto (User user)

{

UserDto userDto=this.mapper.map(user, UserDto.class);

// userDto.setUserId(user.getUserId());

// userDto.setName(user.getName());

// userDto.setEmail(user.getEmail());

// userDto.setDepartment(user.getDepartment());

// userDto.setPassword(user.getPassword());

// userDto.setRegion(user.getRegion());

return userDto;

}

------------------------- pom.xml ----------------------------

<?xml version="1.0" encoding="UTF-8"?>

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"

xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">

<groupId>org.springframework.boot</groupId>

<artifactId>spring-boot-starter-parent</artifactId>

</parent>

<groupId>com.ramsis</groupId>

<artifactId>restApiWithValidationErrorHandling</artifactId>

<version>0.0.1-SNAPSHOT</version>

<name>restApiWithValidationErrorHandling</name>

<description>Demo project for Spring boot Exception Handling and validation</description>

<java.version>11</java.version>

</properties>

<groupId>org.springframework.boot</groupId>

<artifactId>spring-boot-starter-data-jpa</artifactId>

</dependency>

<groupId>org.springframework.boot</groupId>

<artifactId>spring-boot-starter-web</artifactId>

</dependency>

<groupId>org.springframework.boot</groupId>

<artifactId>spring-boot-devtools</artifactId>

<scope>runtime</scope>

</dependency>

<groupId>com.mysql</groupId>

<artifactId>mysql-connector-j</artifactId>

<scope>runtime</scope>

</dependency>

<groupId>org.projectlombok</groupId>

<artifactId>lombok</artifactId>

</dependency>

<groupId>org.springframework.boot</groupId>

<artifactId>spring-boot-starter-test</artifactId>

</dependency>

<groupId>org.modelmapper</groupId>

<artifactId>modelmapper</artifactId>

</dependency>

<groupId>org.springframework.boot</groupId>

<artifactId>spring-boot-starter-validation</artifactId>

</dependency>

</dependencies>

<build>

<groupId>org.springframework.boot</groupId>

<artifactId>spring-boot-maven-plugin</artifactId>

<groupId>org.projectlombok</groupId>

<artifactId>lombok</artifactId>

</exclude>

</excludes>

</configuration>

</plugin>

</plugins>

</build>

</project>

------------------------------ application.properties -------------------------

spring.datasource.driverClassName=com.mysql.cj.jdbc.Driver

spring.datasource.url=jdbc:mysql://localhost:3306/test

spring.datasource.username=root

spring.datasource.password=cctns@123

spring.jpa.show-sql = true

spring.jpa.properties.hibernate.format_sql=true

logging.level.org.hibernate.type.descriptor.sql=trace

spring.jpa.hibernate.ddl-auto = update

#spring.jpa.hibernate.ddl-auto = none

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Saturday 24 June 2023

Exception Handling and Validation in Spring Boot

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