NiFi中EvaluateJsonPathAttributeCustom提取数值型经纬度失败如何解决？

问题场景 #

使用InvokeHTTPCustom调用API获取JSON格式返回数据后，可正常提取字符串类型字段，但提取metadata下数值类型的latitude、longitude字段时，EvaluateJsonPathAttributeCustom处理器报错。

现有JSON样例 #

[
    {
        "input_index": 0,
        "candidate_index": 0,
        "delivery_line_1": "1 Santa Claus Ln",
        "last_line": "North Pole AK 99705-9901",
        "delivery_point_barcode": "997059901010",
        "components": {
            "primary_number": "1",
            "street_name": "Santa Claus",
            "street_suffix": "Ln",
            "city_name": "North Pole",
            "state_abbreviation": "AK",
            "zipcode": "99705",
            "plus4_code": "9901",
            "delivery_point": "01",
            "delivery_point_check_digit": "0"
        },
        "metadata": {
            "record_type": "S",
            "zip_type": "Standard",
            "county_fips": "02090",
            "county_name": "Fairbanks North Star",
            "carrier_route": "C004",
            "congressional_district": "AL",
            "rdi": "Commercial",
            "elot_sequence": "0001",
            "elot_sort": "A",
            "latitude": 64.75233,
            "longitude": -147.35297,
            "coordinate_license": 1,
            "precision": "Rooftop",
            "time_zone": "Alaska",
            "utc_offset": -9,
            "dst": true
        },
        "analysis": {
            "dpv_match_code": "Y",
            "dpv_footnotes": "AABB",
            "dpv_cmra": "N",
            "dpv_vacant": "N",
            "dpv_no_stat": "Y",
            "active": "Y",
            "footnotes": "L#"
        }
    },
    {
        "input_index": 1,
        "candidate_index": 0,
        "addressee": "Apple Inc",
        "delivery_line_1": "1 Infinite Loop"
    }
]

现有EvaluateJsonPathAttributeCustom配置 #

Attribute Name Input : x**.json
Attribute Name Output : latitude
JsonPathExpresssion : $[0].metadata.latitude
Splitif.. : False

解决方法 #

报错核心原因是EvaluateJsonPathAttributeCustom默认对非字符串类型的直接解析存在类型转换异常，按以下两种方案调整即可：

• 方案1：修改JsonPath表达式，强制转换为字符串
  将JsonPathExpresssion参数值修改为$[0].metadata.latitude.toString()，经度对应修改为$[0].metadata.longitude.toString()，其余配置保持不变即可。提取后的经纬度会以字符串格式存入属性，后续如需数值运算，可通过UpdateAttribute处理器的表达式二次转换。
• 方案2：更换处理器适配数值类型
  改用官方原生EvaluateJsonPath处理器，将Return Type参数配置为auto-detect或number，即可直接正确识别JSON中的数值类型字段，无需额外做类型转换。

内容的提问来源于stack exchange，提问作者Shubham Patwa