public async Task <ActionResult <List <Supplier> > > GetAllSuppliers() { var result = await _clkService.findAllSuppliersAsync(); if (result != null) { //Docs says that Ok(...) will AUTO TRANSFER result into JSON Type return(Ok(result)); } else { //this help to return a NOTfOUND result, u can customerize the string. return(NotFound("Suppliers not found")); } }