Dataweave XML-XML转换“无法强制将a：数组转换为：字符串”。

Question

我使用Dataweave重新格式化从有效载荷将XML格式的节目期待：

有效载荷

<reservation> 
    <id>1</id> 
    <begin_time>12:00 PM</begin_time> 
    <end_time>1:00 PM</begin_time> 
    <other_field>Misc. Data</other_field> 
</reservation> 
. 
. 
. 

预期输出。

<reservation> 
    <id>1</id> 
    <begin_time>12:00 PM</begin_time> 
    <schedule> 
     <begin_time>12:00 PM</begin_time> 
     <end_time>1:00 PM</end_time> 
    </schedule> 
</reservation> 
. 
. 
. 

Dataweave代码

%dw 1.0 
%output application/xml 
%namespace ns0 http://www.collegenet.com/r25 
--- 
using (r = (flatten payload.ns0#reservations.*ns0#reservation)) 

    Reservation: r groupBy $.ns0#reservation_id pluck { 
     id : $.ns0#reservation_id , 
     StartTime: $.ns0#reservation_start_dt, 
     Schedule : { 
      ReservationStartDate : $.ns0#reservation_start_dt, 
      PreEventDate : $.ns0#pre_event_dt, 
      EventStartDate : $.ns0#event_start_dt, 
      PostEventDate : $.ns0#post_event_dt, 
      ReservationEndDate : $.ns0#reservation_end_dt 
     } 
    } 

每当我尝试这个代码，我得到一个错误：

"Exception while executing: Reservation: r map { ^ Cannot coerce a :array to a :object."

当我尝试完全相同的代码，但转换成JSON，而不是XML，改造工程完美。如果我删除了该地图的代码，但它会加入同一标题下所有预订的所有ID。我不明白为什么Anypoint将xml解释为数组而不是对象。

Answer 1

您需要注意的第一件事是，无论何时使用map进行迭代，必须使用$和$$访问当前元素数据。这里r.ns0#reservation_id试图强制：来自：数组的对象。尝试将代码更改为

%dw 1.0 
%output text/xml 
%namespace ns0 http://www.mynamespace.com/ns0 
--- 
using (r = (flatten payload.ns0#reservations.*ns0#reservation)) 

Reservation: r map { 
    id : $.ns0#reservation_id, 
    StartTime: $.ns0#reservation_start_dt, 
    Schedule : { 
     ReservationStartDate : $.ns0#reservation_start_dt, 
     ReservationEndDate : $.ns0#reservation_end_dt 
    } 
} 

还观察到输入XML具有与代码中使用的名称不同的标记名称。为更多的可读性，你可以使用拉姆达与地图

%dw 1.0 
%output text/xml 
%namespace ns0 http://www.mynamespace.com/ns0 
--- 
using (r = (flatten payload.ns0#reservations.*ns0#reservation)) 

Reservation: r map ((reservation, reservationIndex) -> { 
    id : reservation.ns0#reservation_id, 
    StartTime: reservation.ns0#reservation_start_dt, 
    Schedule : { 
     ReservationStartDate : reservation.ns0#reservation_start_dt, 
     ReservationEndDate : reservation.ns0#reservation_end_dt 
    } 
}) 

希望这会有所帮助。