Mule解析固定宽度FlatFile为JSON遇WARDS结构未定义错误求助

问题背景 #

读取服务器返回的固定宽度响应（示例：PQRSBNGL1234567890AAHG），通过给定FFD文件和DataWeave脚本转换为JSON时，报错：java.lang.IllegalStateException - Structure WARDS not defined in schema。

错误原因 #

1. FFD结构歧义：FFD文件定义了两个同级顶级结构（HOSPITALS和WARDS），但输入的固定宽度字符串总长度（22位）刚好匹配HOSPITALS的结构长度（4+4+10+4=22），FFD解析器仅识别并解析出HOSPITALS结构，WARDS未被加载，导致脚本访问WARDS时提示结构未定义。
2. 脚本引用错误：DataWeave脚本错误地尝试访问不存在的WARDS结构，且单条数据使用map遍历属于冗余操作（map用于数组遍历，单条对象会引发异常）。

修正方案 #

方案1：输入为单条HOSPITALS数据，需转换为WARDS结构JSON #

步骤1：优化FFD文件（可选，消除歧义）

删除多余的WARDS顶级结构，或在Mule连接器配置中指定解析结构为HOSPITALS。调整后的FFD：

values:
- name: 'HOSPITALS'
  values:
  - name: 'BASIC-INFO'
    values:
    - { name: 'NAME', type: String, length: 4 }
    - { name: 'ADDRESS', type: String, length: 4 }
    - { name: 'PHONE-NUMBER', type: Integer, length: 10, format: { justify: ZEROES, sign: UNSIGNED } }
    - { name: 'ADMIN', type: String, length: 4 }

步骤2：修正DataWeave脚本

从解析后的HOSPITALS结构取值，映射到目标Wards结构，移除不必要的map：

output application/json
---
{
  Wards: {
    "Basic-Info": {
      Name: payload.HOSPITALS."BASIC-INFO".NAME default "",
      Address: payload.HOSPITALS."BASIC-INFO".ADDRESS default "",
      Number: payload.HOSPITALS."BASIC-INFO"."PHONE-NUMBER" default 0,
      Admin: payload.HOSPITALS."BASIC-INFO".ADMIN default ""
    }
  }
}

方案2：输入包含多条HOSPITALS/WARDS数据 #

如果输入是多条固定宽度记录的拼接，需调整FFD为数组结构，并修改脚本适配多类型记录：

调整后的FFD文件

values:
- name: 'RECORDS'
  type: array
  values:
  - name: 'HOSPITALS'
    values:
    - name: 'BASIC-INFO'
      values:
      - { name: 'NAME', type: String, length: 4 }
      - { name: 'ADDRESS', type: String, length: 4 }
      - { name: 'PHONE-NUMBER', type: Integer, length: 10, format: { justify: ZEROES, sign: UNSIGNED } }
      - { name: 'ADMIN', type: String, length: 4 }
  - name: 'WARDS'
    values:
    - name: 'BASIC-INFO'
      values:
      - { name: 'NAME', type: String, length: 4 }
      - { name: 'ADDRESS', type: String, length: 4 }
      - { name: 'NUMBER', type: Integer, length: 10, format: { justify: ZEROES, sign: UNSIGNED } }
      - { name: 'ADMIN', type: String, length: 4 }

修正后的DataWeave脚本

遍历数组，根据记录类型映射输出：

output application/json
---
payload.RECORDS map (record) -> 
  if (record.HOSPITALS?) {
    Wards: {
      "Basic-Info": {
        Name: record.HOSPITALS."BASIC-INFO".NAME default "",
        Address: record.HOSPITALS."BASIC-INFO".ADDRESS default "",
        Number: record.HOSPITALS."BASIC-INFO"."PHONE-NUMBER" default 0,
        Admin: record.HOSPITALS."BASIC-INFO".ADMIN default ""
      }
    }
  } else if (record.WARDS?) {
    Wards: {
      "Basic-Info": {
        Name: record.WARDS."BASIC-INFO".NAME default "",
        Address: record.WARDS."BASIC-INFO".ADDRESS default "",
        Number: record.WARDS."BASIC-INFO".NUMBER default 0,
        Admin: record.WARDS."BASIC-INFO".ADMIN default ""
      }
    }
  }

内容的提问来源于stack exchange，提问作者Abhinay kumar suraj