保存短关联

何谓短关联

所谓短关联，指只改变当前对象和其他对象之间的关联关系，不进一步修改关联对象。

对于UI界面而言

• 引用关联 (一对一和多对一) 表现为单选菜单

• 集合关联 (一对多和多对多) 表现为多选菜单

例如：

Book Form

Name

Name

Edition

Edition

Price

Price

Store

O'REILLY

Authors

Authors

Eve Procello, Alex Banks

Authors

定义Input DTO

1. 安装DTO语言Intellij插件：https://github.com/ClearPlume/jimmer-dto （此过程不是必须的，但非常推荐）

2. 新建目录src/main/dto

3. 在src/main/dto下建立一个文件Book.dto，编写代码如下

   Book.dto

   input BookInputWithShortAssociations {
       #allScalars(this)
       id(store) //默认别名storeId
       id(authors) as authorIds
   }

生成的代码

Java

BookInputWithShortAssociations.java

@GeneratedBy(
        file = "<yourproject>/src/main/dto/Book.dto"
)
public class BookInputWithShortAssociations implements Input<Book> {

    @Nullable
    private Long id;

    @NotNull
    private String name;

    private int edition;

    @NotNull
    private BigDecimal price;

    @Nullable
    private Long storeId;

    @NotNull
    private List<Long> authorIds;

    ...省略其他方法...
}

Kotlin

BookInputWithShortAssociations.kt

@GeneratedBy(
        file = "<yourproject>/src/main/dto/Book.dto"
)
data class BookInputWithShortAssociations(
    val id: Long?,
    val name: String,
    val edition: Int,
    val price: BigDecimal,
    val storeId: Long?
    val authorIds: List<Long>
) : Input<Book> {
    ...省略其他方法...
}

编写HTTP服务

Java

BookController.java

@RestController
public class BookController {

    private final JSqlClient sqlClient;

    public BookController(JSqlClient sqlClient) {
        this.sqlClient = sqlClient;
    } 

    @PutMapping("/book")
    pubic int saveBookInputWithShortAssociations(
        @RequestBody BookInputWithShortAssociations input
    ) {
        return sqlClient
            .save(input)
            .getTotalAffectedRowCount();
    }
}

Kotlin

BookController.java

class BookController(
    private val sqlClient: KSqlClient
) {

    @PutMapping("/book")
    fun saveBookInputWithShortAssociations(
        @RequestBody input: BookInputWithShortAssociations
    ): Int =
        sqlClient
            .save(input)
            .totalAffectedRowCount
}

可见，无论Input DTO如何改变，Jimmer仍然只需一个方法调用即可完成数据保存。