JSONPath get the id of a parent element by a sub-child value

问题

Given the following JSON I want to get the id field of the parent by an equals text compare of a sub-child element:

{
    "datapoints": [{
            "id": "default.1",
            "definedBy": "default/0.1",
            "featureValues": {
                "bui.displayname": "Health status",
                "bui.visibility": "normal",
                "default.access": "r",
                "default.basetype": "text",
                "default.description": "Aggregated health status",
                "default.format": "text/plain",
                "default.name": "health_status",
                "default.restriction": "re:(OK|WARN|ERROR|UNKNOWN)"
            }
        }, {
            "id": "kdl.240",
            "definedBy": "kdl/0.9",
            "featureValues": {
                "bui.displayname": "Delta K",
                "bui.visibility": "normal",
                "default.access": "rw",
                "default.basetype": "real",
                "default.description": "Delta K",
                "default.name": "Delta_K",
                "default.privacy": "false",
                "default.restriction": "b32"
            }
        }
    ]
}

My first goal is to get the correct data point by a sub-child text compare like:

$['datapoints'][*]['featureValues'][?(@['default.name']=='Delta_K')]

It seems not to work when I test it on http://jsonpath.com/ To get all the data points I used this successfully:

$['datapoints'][*]['featureValues']['default.name']

My goal is to get the id value of the data point with the featureValues child element default.name is equal Delta_K. In the example this would be kdl.240.

回答1:

I could only solve the first part of my question by using:

$['datapoints'][*][?(@['default.name']=='Delta_K')]

During my research I found that jsonpath does not support to get the parent of a filtered node. In Chapter 7 "Conclusion" of http://www.baeldung.com/guide-to-jayway-jsonpath it's written:

Although JsonPath has some drawbacks, such as a lack of operators for reaching parent or sibling nodes, it can be highly useful in a lot of scenarios.

Also further SO posts couldn't help me.

Getting parent of matched element with jsonpath
Using jsonpath to get parent node

回答2:

#cat jsonData.json | jq ‘.datapoints[].featureValues | select .default.name == 'Delta_K') | .id’

see also: https://github.com/adriank/ObjectPath/issues/70

来源：https://stackoverflow.com/questions/45543003/jsonpath-get-the-id-of-a-parent-element-by-a-sub-child-value

标签

json

jsonpath