Spring boot 如何编辑实体

Question

I am using spring boot with spring data jpa and postgre. I have "item" entity that has price, quantity, auto generated int id and order that it belongs to. I've searched how to edit that entity changing its price and quantity only, without making new entity and the only answer I got is to get the entity from the db and set each property to the new one then save it. But if i have 6 other properties except price and quantity that means in the update method i will set a property 8 times and this seems to me like way too much boilerplate code for spring. My question is: Is there better/default way to do that?

Answer 1

You can provide a copy constructor :

public Item(Item item) {
    this(item.price, item.quantity); 
}

or use org.springframework.beans.BeanUtils method:

BeanUtils.copyProperties(sourceItem, targetItem, "id"); 

Then in controller:

@RestController
@RequestMapping("/items")
public class ItemController {

    @Autoware
    private ItemRepo repo;

    @PutMapping("/{id}")
    public ResponseEntity<?> update(@PathVariable("id") Item targetItem,  @RequestBody Item sourceItem) {
        BeanUtils.copyProperties(sourceItem, targetItem, "id");
        return ResponseEntity.ok(repo.save(targetItem));
    }
}

Answer 2

No, you don't need to set anything for 8 times. If you want to change price and quantity only, just change those two. Put it in a @Transactional method:

@Transactional
public void updateItem(Item item){
    // ....
    // EntityManager em;
    // ....

    // Get 'item' into 'managed' state
    if(!em.contains(item)){
        item = em.merge(item);
    }

    item.price = newPrice;
    item.quantity = newQuantity;
    // You don't even need to call save(), JPA provider/Hibernate will do it automatically.
}

This example will generate a SELECT and a UPDATE query. And that's all.

Answer 3

Try using @Query annotation and define your update statement

 @Modifying
 @Transactional
 @Query("update Site site set site.name=:name where site.id=:id")
 void updateJustNameById(@Param("id")Long id, @Param("name")String name);

Answer 4

You should use spring data rest which handles all of this by itself. you just have to call a patch request at the specified URL and provide the changed entity properties. if you have some knowledge of spring data rest have a look at https://github.com/ArslanAnjum/angularSpringApi .

Answer 5

Just use this @DynamicUpdate in your Entity class

@DynamicUpdate
public class Item{
}