如何构造JMESPath查询路径以提取指定_instrumentIdScheme对应的#value值

核心查询语句 #

你可以使用如下JMESPath表达式完成查询：
[*]."m:assetPricing"[*]."m:instrumentId"[? _instrumentIdScheme == 'mhi:MHILIST']."#value"
如果需要直接获取字符串形式的结果，可增加展平操作：
[*]."m:assetPricing"[*]."m:instrumentId"[? _instrumentIdScheme == 'mhi:MHILIST']."#value" | [] | [0]

语法说明 #

• 带特殊符号（冒号、#）的键名必须用双引号包裹，否则JMESPath会识别为语法错误
• [? 条件]是JMESPath的过滤表达式，用于筛选符合指定条件的数组元素
• 末尾的| []用于把多层嵌套的数组合并为一层，[0]用于取出第一个匹配到的结果值

Python调用示例 #

import jmespath

# 你已转换完成的JSON数据
target_data = [
    {
        "_fpmlVersion": "5-6",
        "header": {
            "messageType": "PrevDayCloseBond",
            "sendTo": [
                {
                    "#value": "Anvil"
                }
            ],
            "creationTimestamp": "2021-09-28T06:00:00.000Z"
        },
        "m:asOfDate": {
            "#value": "2021-09-28T00:00:00.000Z"
        },
        "_xmlns": "http://www.fpml.org/FpML-5/reporting",
        "_xmlns:m": "urn:com.mizuho.bdm",
        "_xmlns:mhi": "urn:com.mizuho.bdm.mhi",
        "_xmlns:xsi": "http://www.w3.org/2001/XMLSchema-instance",
        "_xsi:schemaLocation": "http://www.fpml.org/FpML-5/reporting http://svc-bdmentity01p:8080/schema/7.2.0/com/mizuho/bdm/fpml/fpml-5-6-reporting.xsd urn:com.mizuho.bdm http://svc-bdmentity01p:8080/schema/7.2.0/com/mizuho/bdm/fpml/mizuho-fpml.xsd urn:com.mizuho.bdm.mhi http://svc-bdmentity01p:8080/schema/7.2.0/com/mizuho/bdm/mhi/fpml/mhi-fpml.xsd",
        "m:assetPricing": [
            {
                "m:pricingSource": [
                    {
                        "#value": "LON-XEN-BBG"
                    },
                    {
                        "#value": "BGN",
                        "_pricingSourceScheme": "mizuho:bloomberg-source"
                    }
                ],
                "m:instrumentId": [
                    {
                        "#value": "100001380992",
                        "_instrumentIdScheme": "mhi:MHILIST"
                    },
                    {
                        "#value": "100001380992",
                        "_instrumentIdScheme": "mhsa:instrument-id"
                    }
                ],
                "m:currency": {
                    "#value": "USD"
                },
                "m:price": [
                    {
                        "value": 140.78125,
                        "measureType": {
                            "#value": "Bid Price",
                            "_assetMeasureScheme": "mizuho:price-type"
                        }
                    },
                    {
                        "value": 140.875,
                        "measureType": {
                            "#value": "Mid Price",
                            "_assetMeasureScheme": "mizuho:price-type"
                        }
                    },
                    {
                        "value": 140.96875,
                        "measureType": {
                            "#value": "Offer Price",
                            "_assetMeasureScheme": "mizuho:price-type"
                        }
                    }
                ]
            }
        ],
        "m:pricingDate": "2021-09-28T00:00:00.000Z"
    }
]

# 执行查询
query_exp = '[*]."m:assetPricing"[*]."m:instrumentId"[?_instrumentIdScheme == \'mhi:MHILIST\']."#value" | [] | [0]'
result = jmespath.search(query_exp, target_data)
print(result)
# 输出结果：100001380992

内容的提问来源于stack exchange，提问作者Bruno Lorena