json path expression to get root key - json

Question

I have this json:
{
"-1": {
"description": "test1"
},
"222": {
"description": "test2"
},
"223": {
"description": "test3"
},
"224": {
"description": "test4"
},
"recordsCount": 4
}
Using this Json path expression: $.. it returns all the Json.
I would like to find the Json path expression that returns only the ID values:
"-1"
"222"
"223"
"224"
Can you help me?

Answer 1

Accessing the property (key) instead of the value is a feature not present in the original JSONPath specifications, and only a few implementation support this feature. So, no luck using the JMeter JsonPath Plugin/Extractor extracting only property names.
For instance, JsonPath-Plus for JavaScript offers the operator ~ for grabbing property names of matching items.
As an alternative, you could use JSR223 Groovy to get the results from JSON:
import groovy.json.JsonSlurper;
import groovy.json.JsonOutput; //if output as JSON is needed
JsonSlurper JSON = new JsonSlurper ();
jsonResponse = JSON.parseText(prev.getResponseDataAsString());
//println json.keySet() //[-1, 222, 223, 224, recordsCount]
vars.put("firstName", response.members[2].firstName.toString());
Set<String> keySet=obj.keySet();
List<String> keys = [];
// iterate over the key set, adding only numbers to result list
for(String key:keySet){
if(key.isNumber())
keys.add(key);
}
//println(keys); //[-1, 222, 223, 224]
def output = JsonOutput.toJson(keys); //convert to JSON string if neede
//println(output); //["-1","222","223","224"]
vars.put("jsonKeys", output.toString());
Demo: Online Groovy sample.
More information:
How to extract data from JSON response using JMETER (See 8.3 JSR223 with Groovy)
Scripting JMeter Assertions in Groovy - A Tutorial
Jayway JsonPath (alternative Java JSONPath library)