title: How to inject json coming from feeder inside body with gatling
body: <p>I have a gatling scenario which </p>
  
  <ol>
  <li>create a Http object</li>
  <li>create a post request with a body</li>
  <li>set up the scenario</li>
  </ol>
  
  <p>I can inject a body from a json file containing this:</p>
  
  <pre><code>[{"id":"1"}]
  </code></pre>
  
  <p>At this point I have no problem. My question is on the second point. I want users to have theirs body feed with different id. So I think I have to use a feeder in order to set body for each user from a json Array. The json file that I use as feeder is like this:</p>
  
  <pre><code>[{
      "id":"1"},
      {"id":"2"},
      {"id":"3"},
      {"id":"4"},
      {"id":"5"},
      {"id":"6"},
      {"id":"7"},
      {"id":"8"},
      {"id":"9"},
      {"id":"10"},
      {"id":"11"},
      {"id":"12"},
      {"id":"13"}
  ]
  </code></pre>
  
  <p>I don't know the syntax to inject inside the body value coming from feeder. I have a fake body line in the code below, wich don't work you bet, but I don't what should replace this line. The line has a comment: </p>
  
  <pre><code>import io.gatling.core.Predef._
  import io.gatling.http.Predef._
  import io.gatling.jdbc.Predef._
  import io.gatling.http.HeaderNames._
  import io.gatling.http.request._
  
  import scala.concurrent.duration._
  import scala.concurrent.duration._
  
  
  class BasicSimulation extends Simulation {
  
    val httpConf = http
      .baseURL("http://localhost:8099")
      .headers(Map("Content-Type" -&gt; "application/json"))
      .doNotTrackHeader("1")
      .acceptLanguageHeader("en-US,en;q=0.5")
      .acceptEncodingHeader("gzip, deflate")
      .userAgentHeader("Mozilla/5.0 (Windows NT 5.1; rv:31.0) Gecko/20100101 Firefox/31.0")
  
    val feeder = jsonFile("src/test/resources/json/gatling/test.json")
  
    val scnPost = scenario("BasicSimulation")
      .feed(feeder)
      .exec(http("request_1")
        .post("/spring-test")
        //I have to replace this line...
        .body(RawFileBody("${.}"))
        .check(status.is(200)))
  
    setUp(
      scnPost.inject(constantUsersPerSec(3) during(3 seconds))
    ).protocols(httpConf)
  }
  </code></pre>
  
  <p>Do you have any idea, how to inject json inside body from feeder?</p>