Gatling 更新文件用于在调用之前在 feed() 中提供模拟

Question

I need to update.csv file containing some ids used within Gatling simulation, as I need to create data beforehand. I tried to update that file within before() call however it won't work. Lazy evaluation won't work either.

  before {
    Helper.CreateDocuments()
  }

  lazy val documentIds = csv("data/documentIds.csv").circular

  val scn: ScenarioBuilder = scenario("PutFile")
    .feed(documentIds)
    .exec(http("Dynamic id")
      .put("files/${documentId}"))...

How can I solve that issue to feed simulation with refreshed ids?

Answer 1

I've faced similar issue, and then I decided to not use CSV, but implicit feeders and to create a method to build my feeder. I wasn't able to fix that by using the before hook, so created a builder method for my feeder. An example on how it would work.

import io.gatling.core.Predef._
import io.gatling.core.structure.ChainBuilder
import io.gatling.http.Predef._
import org.apache.http.client.methods.{HttpGet, HttpPost}
import org.apache.http.entity.StringEntity
import org.apache.http.impl.client.HttpClientBuilder
import org.apache.http.util.EntityUtils
import spray.json.DefaultJsonProtocol._
import spray.json._

object TestFacade {    
var test_feeder = getFeeder()
    
      val test_scenario: ChainBuilder = feed(test_feeder).group("TEST_GROUP") {
        exec(
          http("POST /test")
            .post("/test")
            .header("Content-Type", Configuration.APPLICATION_JSON)
            .body(ElFileBody("test.json"))
            .asJSON
            .check(status.find.in(200))
        )
      }
    
      def getFeeder() = {
        val result = getRestContent("http://www.randomnumberapi.com/api/v1.0/random?min=100&max=1000&count=5")
    
        val ids = result.parseJson.convertTo[Array[Int]]
        var coolVars = Array.empty[Map[String, String]]
    
        for (id <- ids) {
          println(id)
          coolVars = coolVars :+ Map("coolVar" -> id.toString)
        }
    
        coolVars.random
      }
      
      def getRestContent(url: String): String = {
        val httpClient = HttpClientBuilder.create().build()
        val httpResponse = httpClient.execute(new HttpGet(url))
        val entity = httpResponse.getEntity
        var content = ""
        if (entity != null) {
          content = EntityUtils.toString(entity, "UTF-8")
        }
        httpClient.getConnectionManager.shutdown()
    
        content
      }
}

Answer 2

just use initializing method to create the file, it will process before all stuff and should work

  /**
   * customize before
   */
  {
    Helper.CreateDocuments()
  }

Answer 3

You should be able to modify a csv file in the before step. For example:

  before {
    val pw = new PrintWriter(new File("data.csv"))
    for (i <- 0 to 10) {
      pw.write(i + "\n")
    }
    pw.close
  }

Remember to import the library import java.io._

And then use it in your simulation calling the file:

val orderId = csv("data.csv").queue

However this might be redundant as you can create the values an use the saveAs step, as mentioned in the Gatling Session API documentation . For example you can do something like:

val someHttpCall = http("Create data for the feeder").get("/my/resource").saveAs("data")

And then use in the feeder:

val scn = feed(data).exec(somethingElse)

If this is not enough, remember that you can also create you own feeder at any point in the simulation class.