Extract JSON value using Jmeter - json

Question

I have this JSON:
{
"totalMemory" : 12206567424,
"totalProcessors" : 4,
"version" : "0.4.1",
"agent" : {
"reconnectRetrySec" : 5,
"agentName" : "1001",
"checkRecovery" : false,
"backPressure" : 10000,
"throttler" : 100
},
"logPath" : "/eq/equalum/eqagent-0.4.1.0-SNAPSHOT/logs",
"startTime" : 1494837249902,
"status" : {
"current" : "active",
"currentMessage" : null,
"previous" : "pending",
"previousMessage" : "Recovery:Starting pipelines"
},
"autoStart" : false,
"recovery" : {
"agentName" : "1001",
"partitionInfo" : { },
"topicToInitialCapturePosition" : { }
},
"sources" : [ {
"dataSource" : "oracle",
"name" : "oracle_source",
"captureType" : "directOverApi",
"streams" : [ ],
"idlePollingFreqMs" : 100,
"status" : {
"current" : "active",
"currentMessage" : null,
"previous" : "pending",
"previousMessage" : "Trying to init storage"
},
"host" : "192.168.191.5",
"metricsType" : { },
"bulkSize" : 10000,
"user" : "STACK",
"password" : "********",
"port" : 1521,
"service" : "equalum",
"heartbeatPeriodInMillis" : 1000,
"lagObjective" : 1,
"dataSource" : "oracle"
} ],
"upTime" : "157 min, 0 sec",
"build" : "0-SNAPSHOT",
"target" : {
"targetType" : "equalum",
"agentID" : 1001,
"engineServers" : "192.168.56.100:9000",
"kafkaOptions" : null,
"eventsServers" : "192.168.56.100:9999",
"jaasConfigurationPath" : null,
"securityProtocol" : "PLAINTEXT",
"stateMonitorTopic" : "_state_change",
"targetType" : "equalum",
"status" : {
"current" : "active",
"currentMessage" : null,
"previous" : "pending",
"previousMessage" : "Recovery:Starting pipelines"
},
"serializationFormat" : "avroBinary"
}
}
I trying using Jmeter to extract out the value of agentID, how can I do that using Jmeter, what would be better ? using extractor or json extractor?
what I am trying to do is to extract agentID value in order to use it on another http request sample, but first I have to extract it from this request.
thanks!

Answer 1

I believe using JSON Extractor is the best way to get this agentID value, the relevant JsonPath query will be as simple as $..agentID
Demo:
See the following reference material:
JsonPath - Getting Started - for initial information regarding JsonPath language, functions, operators, etc.
JMeter's JSON Path Extractor Plugin - Advanced Usage Scenarios - for more complex scenarios.