postman pre-request script (post raw)

var random_id = parseInt(Math.random() * 10000);
pm.environment.set("random_id", random_id);
var domain = pm.environment.get("domain");

pm.sendRequest({
    url: "https://api"+domain+"./signup",
    method: 'POST',
    header: {
        'Content-Type': 'application/json',
          },
    body: {
        mode: 'raw',
        raw: JSON.stringify({"email":"test",
                             "password":"test"})
                            }
}, function (err, response) {
        pm.environment.set("token", response.json().data.token);
        pm.environment.set("id", response.json().data.user.data.id);

});