我有一个（Groovy）Spring Boot应用程序与H2内存数据库对话（但不要认为这很重要）。我有以下cd实体：
GroceryItem然后是@MappedSuperclass
abstract class BaseEntity {
@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
Long id
}
@Canonical
@TupleConstructor(includeSuperProperties = true)
@ToString(includeSuperProperties = true)
@Entity(name = 'grocery_items')
@AttributeOverrides([
@AttributeOverride(name = "id", column=@Column(name="grocery_item_id"))
])
class GroceryItem extends BaseEntity {
@Column(name = 'grocery_item_name')
@NotNull
@Valid
String name
@Column(name = 'grocery_item_qty')
@NotNull
Integer quantity
}
接口：
CrudRepository但由于某些原因，此interface GroceryItemPersistor extends CrudRepository<GroceryItem, Long> {
@Query('FROM grocery_items WHERE grocery_item_name = :name')
GroceryItem findByName(@Param('name') String name)
@Query('FROM grocery_items')
List<GroceryItem> getAllGroceries()
}
CrudRepository方法仅更新并允许我将一个save(...)插入数据库。这意味着如果我运行此代码：
GroceryItem我在控制台上获得以下输出：
GroceryItem olives = new GroceryItem(1L, '123456', 'Olives', 6)
groceryItemPersistor.save(olives)
List<GroceryItem> allItems = groceryItemPersistor.getAllGroceries()
log.info("There are ${allItems.size()} grocery items.")
log.info("${allItems.first().name} are in there right now")
GroceryItem cheeseWedges = new GroceryItem(2L, '067e6162-3b6f-4ae2-a171-2470b63dff00', 'Cheese Wedges', 4)
groceryItemPersistor.save(cheeseWedges)
allItems = groceryItemPersistor.getAllGroceries()
log.info("There are ${allItems.size()} grocery items.")
log.info("${allItems.first().name} are in there right now")
我需要在There are 1 grocery items.
Olives are in there right now.
There are 1 grocery items.
Cheese Wedges are in there right now.
和/或GroceryItem类中修改哪些内容才能BaseEntity正确插入而不是更新？
答案 0 :(得分：1)
创建主键为1的橄榄项目后，您在创建cheeseWedges时传递相同的主键。
GroceryItem cheeseWedges = new GroceryItem(1L, '067e6162-3b6f-4ae2-a171-2470b63dff00', 'Cheese Wedges', 4)
尝试创建新项目时，请勿设置主键。如果您设置它，JPA将尝试更新表中具有相同主键的项目。
答案 1 :(得分：0)
我明白了。我正在创建一个主键并保存它，而不是让JPA在调用@Generated时为我创建save密钥。将我的实体实例化更改为null id：
GroceryItem bananas = new GroceryItem(null, '067e6162-3b6f-4ae2-a171-2470b63dff00', 'Bananas', 12)
...解决了这个问题。