Gatling Inject Dynamic Values into a Json Template
In this example, we will show how to use Gatling to send a POST request with a body using a JSON file template with dynamic values.
This sample project is built using Gatling with Scala and Gradle build tool.
Pre-requisite:
To setup your Gatling project follow the steps defined in Performance Testing Framework with Gatling and Maven
Create the JSON Template File
First create a JSON template file, give it a name and place it under the src/gatling/resources folder:
{
"orderId": "#{orderId}",
"customerId": "#{customerId}",
"amount": 10.00
}
Send Requests with Dynamic Data
Next, in our request object we will create random UUIDs and set a new session, so each request will use a different UUID each time.
var customerId = java.util.UUID.randomUUID()
var orderId = java.util.UUID.randomUUID()
val setNewSession =
exec(setSessionAttributesBulkAdd => {
setSessionAttributesBulkAdd.setAll(
"customerId" -> s"${customerId}",
"orderId" -> s"${orderId}"
)
})
Then we send a request with the JSON file template using the ElFileBody and Gatling will automatically inject the values into the file:
val sendRequestWithDynamicData =
http("Request With Dynamic Values")
.post("/some-endpoint")
.body(ElFileBody("jsonTemplate.json"))
.check(status.is(200))
.check(jsonPath("$.someParam").saveAs("someParamValue"))
Full request object file looks like this:
import io.gatling.core.Predef._
import io.gatling.http.Predef._
object InjectDynamicValues {
var customerId = java.util.UUID.randomUUID()
var orderId = java.util.UUID.randomUUID()
val setNewSession =
exec(setSessionAttributesBulkAdd => {
setSessionAttributesBulkAdd.setAll(
"customerId" -> s"${customerId}",
"orderId" -> s"${orderId}"
)
})
val sendRequestWithDynamicData =
http("Request With Dynamic Values")
.post("/some-endpoint")
.body(ElFileBody("jsonTemplate.json"))
.check(status.is(200))
.check(jsonPath("$.someParam").saveAs("someParamValue"))
}
Scenario
In the Scenario object, we first have to execute the setNewSession request to initialize the values and then execute the sendRequestWithDynamicData request
import io.devqa.requests.InjectDynamicValues
import io.gatling.core.Predef._
object DynamicValuesScenario {
val dynamicValues = scenario("Scenario that injects dynamic values")
.exec(InjectDynamicValues.setNewSession)
.exec(InjectDynamicValues.sendRequestWithDynamicData)
}
Simulation
And finally, the simulation file looks like:
import io.devqa.scenarios.DynamicValuesScenario
import io.gatling.core.Predef._
import scala.concurrent.duration.DurationInt
import scala.language.postfixOps
class DynamicValuesSimulation extends Simulation {
setUp(
DynamicValuesScenario.dynamicValues.inject(
nothingFor(3),
constantUsersPerSec(1) during (60 second))
)
}
You can then play around with different numbers for users and duration to simulate desired load.