Parameterize POST body in JMeter HTTP POST - jmeter

Question

I am using Apache JMeter to run a few performance tests against RESTFUL API for an application that we have developed. I have an end point "api/create/empListJob", which basically adds one or more employee records in the MongoDB. The payload for the POST call looks like this:
{
"employeeList": [
{
"first_name": "josh",
"last_name": "don",
"age": "25",
"address": {
"street1": "xyz",
"street2": "apt-10",
"city" : "def",
"state" : "CA",
"zip" : "95055"
},
"deptType": {
"deptID": "1",
"deptName": "R&D"
}
},
{
"first_name": "mary",
"last_name": "jane",
"age": "22",
"address": {
"street1": "zzz",
"street2": "apt-15",
"city" : "yyy",
"state" : "CA",
"zip" : "95054"
},
"deptType": {
"deptID": "2",
"deptName": "HR"
}
}
]
}
As you can see, the payload takes a list of employee data, and it should have atleast one employee record. I have a requirement in which i want JMeter thread group to have 10 threads and each of these threads should make a concurrent POST to "api/create/empListJob" such that the body has 10 unique employee records, thus creating a total of 100 records. What is the best way that i could parameterize the payload?

Answer 1

Take a look at JMeter Functions, like:
__threadNum() - returns the number of current thread (virtual user)
__Random() - returns a random number in a given range
__RandomString() - returns a random string from specified input characters
__UUID() - returns random GUID structure
So for example if you change your JSON payload to look like:
"employeeList": [
{
"first_name": "josh-${__threadNum}",
"last_name": "don-${__threadNum}",
"age": "25",
"address": {
"street1": "xyz",
"street2": "apt-10",
"city" : "def",
"state" : "CA",
"zip" : "95055"
},
"deptType": {
"deptID": "1",
"deptName": "R&D"
}
},
{
"first_name": "mary-${__threadNum}",
"last_name": "jane-${__threadNum}",
"age": "22",
"address": {
"street1": "zzz",
"street2": "apt-15",
"city" : "yyy",
"state" : "CA",
"zip" : "95054"
},
"deptType": {
"deptID": "2",
"deptName": "HR"
}
}
]
}
JMeter will create:
- `josh-1` for 1st virtual user
- `josh-2` for 2nd virtual usre
- etc.
See Apache JMeter Functions - An Introduction to get familiarized with JMeter Functions concept.