Spring-Data-JPA.txt

Exception Handling:
Controller Level //@ExceptionHandler
	If a Controller is throwing any exception then in that class itself create amethod for @ExceptionHandler(Exception.class)
	which will handle the exceptionof this controller class
	The @ExceptionHandler is an annotation used to handle the specific exceptions and sending the custom responses to the client.
Project Level	//@ControllerAdive
	For global level,Create a class with annotation @ControllerAdive and provide a method with @ExceptionHandler
	have one of your controller methods throw an exception
	catch that exception in the controller using @ExceptionHandler
	catch the exception using Controller Advice
In our project we can create a custom exception which extends any exception.In our service classes we can put a try catch and throw a paticular exception in catch,
which will eventually go to the @ControllerAdive and particular @ExceptionHandler

H2 DB:
it is an in-memeory DB that can be integrated in the spring boot application itself.
Steps for intergration:
1)while downloading SB app select db h2 dependency also
2)in application.properties put
	spring.h2.console.enabled=true
	spring.h2.console.path=/console
3)Run your app
we can view the DB by using complete url of the app then adding the uri/console,we need to loging,without password and then we can view H2 database from our browser


Spring-Data-JPA"
1.To enable auditing on tables i.e Spring JPA automatically update CreatedBy, CreatedDate, LastModifiedBy, LastModifiedDate properties.
->1)In EntityClass use @CreatedBy on the property
  2)Above EntityClass put @EntityListeners(AuditingEntityListener.class)
  3)In the DAO class put @EnableJpaAuditing