Don't need to insert on left join table

I am using a left join just to show a value on the parent table. when I do an insert on the parent table, however, editor is trying to insert on the left join table as well.

I tried .set(false) on all the fields on the left join but that didn't seem to help

when doing an insert where a leftJoin exists, is there a way for the edit/insert only to happen on the 'main' table (JobTitles in this case.

    public class JobTitlesController : ApiController
    {
        [Route("api/JobTitles")]
        [HttpGet]
        [HttpPost]
        public IHttpActionResult JobTitles()
        {
            var request = HttpContext.Current.Request;
            var settings = Properties.Settings.Default;
            var AsOfCookie = request.Cookies.Get("AsOfDate").Value;

            using (var db = new Database(settings.DbType, settings.DbConnection))
            {
                var response = new Editor(db, "JobTitles", "JobTitleID")
                    .Model<JobTitlesModel>("JobTitles")
                    .LeftJoin("JobTitleRates", "JobTitles.JobTitleID", "="
                        , "JobTitleRates.JobTitleID and '" + AsOfCookie + "' Between JobTitleRates.EffectiveDate and isnull(JobTitleRates.ExpireDate,getdate())")
                        .Field(new Field("JobTitleRates.HourlyRate").Set(false))
                        .Field(new Field("JobTitleRates.JobTitleID").Set(false))
                        .Field(new Field("JobTitleRates.JobTitleRateID").Set(false))
                        .Field(new Field("JobTitleRates.EffectiveDate").Set(false))
                        .Field(new Field("JobTitleRates.ExpireDate").Set(false))
                    .Process(request)
                    .Data();

                return Json(response);
            }
        }
    }