Read: 12 - Spring RESTful Routing & Static Files

Spring Request Mapping

• @RequestMapping(value = "/ex/foos", method = RequestMethod.GET) I use it to connect request with methods, then I can extract request information using the @RequestMapping variables.
• @RequestMapping and the HTTP Method: http has no default val, or it map to any request.
• RequestMapping and HTTP Headers @RequestMapping(value = "/ex/foos", headers = "key=val", method = POST.
• RequestMapping With Path Variables
• @PathVariable annotation use it make part of my url variable.
• example : @RequestMapping(value = "/ex/foos/{whatever}/bar/", method = GET) {id} is path var.
  • my method: public String pathVariable( @PathVariable("whatever") int whatever).
• RequestMapping & Request Parameters :
  • @RequestMapping(value = "/ex/bars", params = "id", method = GET)
  • public String reqParam( @RequestParam("id") int id)
• Mapping Shortcuts: @GetMapping @PostMapping @PutMapping @DeleteMapping @PatchMapping
  • Restful API and req map example: source

@GetMapping("/{id}")
public ResponseEntity<?> getBazz(@PathVariable String id){
    return new ResponseEntity<>(new Bazz(id, "Bazz"+id), HttpStatus.OK);
}

@PostMapping
public ResponseEntity<?> newBazz(@RequestParam("name") String name){
    return new ResponseEntity<>(new Bazz("5", name), HttpStatus.OK);
}

@PutMapping("/{id}")
public ResponseEntity<?> updateBazz(
  @PathVariable String id,
  @RequestParam("name") String name) {
    return new ResponseEntity<>(new Bazz(id, name), HttpStatus.OK);
}

@DeleteMapping("/{id}")
public ResponseEntity<?> deleteBazz(@PathVariable String id){
    return new ResponseEntity<>(new Bazz(id), HttpStatus.OK);
}

Accessing Data with JPA

• Spring Data JPA to store and retrieve data in a relational database.
• required Dependencies in srping initializer Spring Data JPA and then** H2 Database**.
• @Entity annotation define entity.
• @Id using this will spring recognize each entity id.
• Simple Queries:

  • Comparing repositories

• CrudRepository provides CRUD functions.
• PagingAndSortingRepository provides methods to do pagination and sort records.
• JpaRepository provides JPA methods such as delete records.
• because of inheritance relationship, the JpaRepository contains the full API of CrudRepository and PagingAndSortingRepositorym.
• it means When I don’t full functionality repo usage, i can go with CrudRepository.

CrudRepository

Crud methods : save()

• save an list of entities.
• we can pass multiple objects to save them in a batch findOne() get a single entity by passing primary key value findAll() – get an list of all available entities in database count() – return the count of total entities in a table delete() – delete an entity based on the passed object exists() – verify if an entity exists based on the passed primary key value.

PagingAndSortingRepository

interface provides a method findAll(Pageable pageable), it help me implement Pagination. pageable object contain at least these 3 props: Page size, Current page number, Sorting.

• Sort sort = new Sort(new Sort.Order(Direction.ASC, "lastName")); Pageable pageable = new PageRequest(0, 5, sort); this code means, sort ascendant by last name and get me only 5 records.

JpaRepository

the interface props findAll() get a List of all available entities in database findAll() get a List of all available entities and sort them using the provided condition save() save an list of entities. Here, we can pass multiple objects to save them in a batch flush() flush all pending task to the database saveAndFlush() save the entity and flush changes immediately deleteInBatch() delete an Iterable of entities. Here, we can pass multiple objects to delete them in a batch