Question

是否可以在一个查询中使用MyBatis将嵌入对象与注释映射，例如：
Foo类：



public class Foo //immutable
{
private final Integer fooId;
private final String fooAttr;
private final Bar bar;
public Foo(Integer fooId, String fooAttr, Bar bar) //constructor
}

public class Foo //immutable { private final Integer fooId; private final String fooAttr; private final Bar bar; public Foo(Integer fooId, String fooAttr, Bar bar) //constructor } 酒吧班：

 public class Bar { //immutable
 private final Integer barId;
 private final String barAttr;
 public Bar(Integer barId, String barAttr) //constructor
}

表FooBar：

 public class Bar { //immutable
 private final Integer barId;
 private final String barAttr;
 public Bar(Integer barId, String barAttr) //constructor
}

查询：

- INT foo_id
- CHAR foo_attr
- INT bar_id
- CHAR bar_attr

- INT foo_id
- CHAR foo_attr
- INT bar_id
- CHAR bar_attr

如何将Bar类映射为Foo构造函数参数（不使用子查询）？

Answer 1

我知道，这很痛苦，但以下情况可行：

@ConstructorArgs({
  @Arg(column="foo_id", javaType=Integer.class),
  @Arg(column="foo_attr", javaType=String.class),
  @Arg(column="bar_id", javaType=Integer.class),
  @Arg(column="bar_attr", javaType=String.class)
})

构造函数应该如下所示：

public Foo(Integer fooId, String fooAttr, Integer barId, String barAttr)
    this.fooId = fooId;
    this.fooAttr = fooAttr;
    this.bar = new Bar(barId, barAttr);
}

如果未设置ID，您甚至可以将栏留空：

public Foo(Integer fooId, String fooAttr, Integer barId, String barAttr)
    this.fooId = fooId;
    this.fooAttr = fooAttr;
    if (barId != null) {
        this.bar = new Bar(barId, barAttr);
    }
}

MyBatis - constructorArgs注释和嵌入对象

1 个答案: