Spring Validations

In this example I have used default validations as well as custom validations

Default Validations

• @NotEmpty
• @Size
• @NotNull
• @DecimalMin
• @Digits
• etc..

   @NotEmpty(message = "{account.name.notempty}")
   @Size(min = 2,max = 50,message = "{account.name.size}")
   private String accountName;
   
   @NotEmpty(message = "{account.type.notempty}")
   @Size(min = 2,max = 50,message = "{account.type.size}")
   private String accountType;
   
   @NotNull(message = "{account.amount.notnull}")
   @DecimalMin(value = "100.00",inclusive = false,message = "{account.amount.min}")
   @Digits(integer=3, fraction=2,message = "{account.amount.decimal}" )
   private BigDecimal amount;

Custom Validation

I have created custom validation like @AlreadyExists, it will check account name is already exists or not in database.

    @AlreadyExists(message = "{alreadyexists.account}")
    public class Account{
    ...
    }
    @Documented
    @Retention(RetentionPolicy.RUNTIME)
    @Target({ElementType.ANNOTATION_TYPE, ElementType.TYPE})
    @Constraint(validatedBy = AlreadyExistsValidator.class)
    public @interface AlreadyExists {
   	String message() default "Invalid value";
       Class<?>[] groups() default {};
       Class<? extends Payload>[] payload() default {};
    }
    
    public class AlreadyExistsValidator implements ConstraintValidator<AlreadyExists, Account>{
    
       @Autowired
       private JdbcAccountRepository repository;
    
       @Override
   	public boolean isValid(Account inputValue, ConstraintValidatorContext context) {
   		log.debug("| Request Time - Start - isValid() " + LocalTime.now());
   		boolean flag = true;
   		if(inputValue.getId() == null) {
   			flag = isValidObjectForSave(inputValue, context);
   		}else {
   			flag = isValidObjectForUpdate(inputValue, context);
   		}
   		return flag;
   	 }
   
   	protected boolean isValidObjectForSave(Account inputValue,ConstraintValidatorContext context) {
   		boolean statusFlag = true; //Default Success
   		List<Account> list = repository.findByName(inputValue.getAccountName());
   		if(list.size() > 0)
   			statusFlag = false; //Failure
   		
   		return statusFlag;
   	}
   
   	protected boolean isValidObjectForUpdate(Account inputValue,ConstraintValidatorContext context) {
   		boolean statusFlag = true; //Default Success
   		List<Account> list = repository.findByName(inputValue.getAccountName());
   		int counter = 0;
   		for(Account account:list) {
   			if (account.getId() != account.getId()) {
   				counter++;
   			}
   		}
   		if (counter > 0)
   			statusFlag = false;
   		return statusFlag;
   	}	 
    }

ValidationMessages.properties

account.name.notempty 	= Account Name is not empty
account.name.size     	= Account Name accepts at least {min} and at most {max} characters
account.type.notempty 	= Account Type is not empty
account.type.size     	= Account Type accepts at least {min} and at most {max} characters
account.amount.notnull 	= Amount is not empty
account.amount.min    	= Account Minimum balance should be 100.entered value ${validatedValue}
account.amount.decimal	= Amount should be in 2 decimal values.entered value ${validatedValue}

alreadyexists.account	= Account name already exists.entered value '${validatedValue.accountName}'
account.id.min		= Please provide the valid account id, entered value ${validatedValue}