Form a JSON request using previous response value in JMETER - jmeter

Question

On my request I am getting the following response,
{
"studyDTO": {
"studyId": 191,
"studyCode": "test_ispptest2"
},
"sites": [],
"subjects": [],
"visits": [],
"sftpLocations": [],
"dicomLocations": [],
"fileSystemLocations": [],
"rawFileSystemLocations": [],
"states": null,
"modalities": [
{
"studyId": 191,
"submitValue": "ct",
"displayValue": "Conventional CT",
"orderOfDisplay": 30
},
{
"studyId": 191,
"submitValue": "multi_slice_spiral_ct",
"displayValue": "Multi-Slice Spiral CT",
"orderOfDisplay": 50
},
{
"studyId": 191,
"submitValue": "dxa",
"displayValue": "DXA",
"orderOfDisplay": 60
},
{
"studyId": 191,
"submitValue": "mri",
"displayValue": "MRI",
"orderOfDisplay": 100
},
{
"studyId": 191,
"submitValue": "unknown",
"displayValue": "Unknown",
"orderOfDisplay": 240
}
],
"examDates": [],
"series": null,
"transferType": null,
"customFolder": false,
"customFile": false,
"folderStructure": null,
"fileStructure": null,
"allSites": true,
"allSubjects": true,
"allVisits": true,
"allStates": false,
"allExamDates": true,
"allModalities": false,
"allSeries": false,
"softEditOverride": false,
"includePS": false,
"includeSR": false,
"includeRTStruct": false,
"dicomTemplate": null,
"errorMessage": null,
"successMessage": null
}
in the response I received 5 modality value this can be more and in my next request body in the JSON type I want to add all the modalities, how I can do this using JSR223 Post-Processer,
Request Sample:
{
"studyDTO": {
"studyId": 191,
"studyCode": "test_ispptest2"
},
"allVisits": true,
"modalities": [
{
"studyId": 191,
"submitValue": "ct",
"displayValue": "Conventional CT",
"orderOfDisplay": 30
},
{
"studyId": 191,
"submitValue": "multi_slice_spiral_ct",
"displayValue": "Multi-Slice Spiral CT",
"orderOfDisplay": 50
},
{
"studyId": 191,
"submitValue": "dxa",
"displayValue": "DXA",
"orderOfDisplay": 60
},
{
"studyId": 191,
"submitValue": "mri",
"displayValue": "MRI",
"orderOfDisplay": 100
},
{
"studyId": 191,
"submitValue": "unknown",
"displayValue": "Unknown",
"orderOfDisplay": 240
}
],
"includePS": null
}
I have developed so far, but don't have a clue to form the request JSON
import groovy.json.JsonSlurper
def jsonString = prev.getResponseDataAsString();
def jsonConvert = new JsonSlurper();
def object = jsonConvert.parseText(jsonString);
def modalityS = object.modalities.size().toString();
def modalitySize = modalityS?.isInteger() ? modalityS.toInteger() : null
for (int i = 0; i < modalitySize ; i++) {
def modalityOrderOfDisplay = object.modalities[i].orderOfDisplay;
def modalSubmitValue = object.modalities[i].submitValue;
def modalDisplayValue = object.modalities[i].displayValue;
log.info('----------------------->'+modalityOrderOfDisplay);
log.info('----------------------->'+modalSubmitValue);
log.info('----------------------->'+modalDisplayValue);
}

Answer 1

Take a look at JsonBuilder class
Something like:
def response = new groovy.json.JsonSlurper().parse(prev.getResponseData())
def request = [:]
request.put('studyDTO', response.studyDTO)
request.put('allVisits', response.allVisits)
request.put('modalities', response.modalities)
request.put('includePS', null)
vars.put('request', new groovy.json.JsonBuilder(request).toPrettyString())
should do the trick for you.
You will be able to refer the generated request body as ${request} where required.
More information:
Apache Groovy - Parsing and producing JSON
Apache Groovy: What Is Groovy Used For?