Failed to map to class with member objects when used with Lombok

Question

The Task class has an instance of TaskPayload as a member object.

@Data
@Builder
public class Task {
    private int id;
    private TaskPayload payload;
    // skipping other members
}

@Data
@Builder
public class TaskPayload {
    private PayloadType payloadType;
    private PayloadEncoding payloadEncoding;
    private String data;
}

I am trying to insert a Task element to the table task_queue and return the inserted element.

    <select id="save" parameterType="com.prod.transponder.entity.Task" resultMap="taskResultMap">
        INSERT INTO task_queue(
            payload_type,
            payload_encoding,
            payload_text
        )
        VALUES
            (
                #{payload.payloadType},
                #{payload.payloadEncoding},
                #{payload.data}
            )
        RETURNING *
    </select>

    <resultMap id="taskPayloadMap" type="com.prod.transponder.model.TaskPayload">
        <result column="payload_encoding" property="payloadEncoding" />
        <result column="payload_type" property="payloadType"/>
        <result column="payload_text" property="data"/>
    </resultMap>

    <resultMap id="taskResultMap" type="com.prod.transponder.entity.Task">
        <id column="id" property="id"/>
        <association property="payload" resultMap="taskPayloadMap"/>
    </resultMap>

But when I test this I get the following error;

Caused by: org.apache.ibatis.executor.result.ResultMapException: Error attempting to get column 'id' from result set.  Cause: java.lang.IllegalArgumentException: No enum constant com.prod.transponder.constants.PayloadType.2

2 is the autogenerated Id of the inserted element.

Answer 1

The error itself is not intuitive enough to solve this issue. The actual problem lies with Lombok's annotations. Mybatis is using Reflection to set values to fields. It needs a no-argument constructor (or no constructor at all) to map the values of the member object. So adding the @NoArgsConstructor annotation on top of the TaskPayload should solve the problem. But since @Builder requires a constructor with all members, one must add @AllArgsConstructor also. Hence modifying TaskPayload like this will fix the issue;

@Data
@Builder
@AllArgsConstructor
@NoArgsConstructor
public class TaskPayload {
    private PayloadType payloadType;
    private PayloadEncoding payloadEncoding;
    private String data;
}

Also, defining the resultMap is unnecessary here. Setting Task as resultType should work aswell.