JMeter: Creating Proper UPDATE Calls for API CRUD Testing - api

Question

I'm performing API testing of basic CRUD functionality. For a record creation, I need to take the response, modify a field, and save the full thing off as a file so i can be recalled for an Update.
Here is what occurs for the creation.
CREATE POST Body
{
"id": 0,
"name": "apiTest: Code Rate ${__Random(1,10000000)}",
"deletable": false,
"codePeriods": null
}
CREATE RESPONSE Body
{
"name": "apiTest: Code Rate 869531",
"id": 1257745140,
"deletable": true,
"codePeriods": null,
"lastChangedDateTime": "03/01/2016 10:13:09",
"lastChangedTime": 36789410,
"createdUser": {
"id": 1003941890,
"userName": "N9SFBulkUser"
},
"lastChangedDate": 736024,
"lastChangedUser": {
"id": 1003941890,
"userName": "N9SFBulkUser"
},
"createdDateTime": "03/01/2016 10:13:09"
}
I need to change the "name" field in order to perform an UPDATE on the record.
As of now, I have:
a RegEx to extract the name field value and save it. (newCodeRate)
a Save Response to a file to save off the entire response. (newCodeRateFile)
another HTTP Request to update the record where:
Body Data = ${__fileToString(${__eval(${newCodeRateFile})},,)}
As you can see, right now it's just taking the previous response, saving it to a file and then being re-sent. This is not a proper UPDATE as the database sees nothing has changed and just ignores it. Sure, I get a 200 OK response, but it's misleading as nothing was updated. You can tell this because the Creation and Update date/times still match.
I was thinking maybe I need a BSF PostProcessor where (using Javascript):
var data = prev.getResponseDataAsString();
var object = JSON.parse(data);
vars.put("name", object.name);
But not being a developer by trade, I'm not sure how what to do with this and how to save the new name value into the saved recallable file.

Answer 1

I don't think you have JSON in BSF JavaScript, it is not part of Rhino
I don't think you need to store response into a file and read it, you can do it in memory.
So:
Change your __Random function to store generated value into a JMeter Variable like:
${__Random(1,10000000,randomNumber)}
Add Regular Expression Extractor as a child of CREATE request and configure it as follows:
Reference Name: anything meaningful, i.e. body
Regular Expression: (?s)(^.*)
Template: $1$
Add __Beanshell function as UPDATE request body, it should look like:
${__BeanShell(return vars.get("body").replaceAll(vars.get("randomNumber")\,"${__Random(1,10000000)}");,)}
See How to Use JMeter Functions posts series for more comprehensive information on JMeter functions.