@using Newtonsoft.Json;
@{
    ViewData["Title"] = "CookUpdate";
}
<div class="text-center">
    <h2 class="display-4">Данные повара</h2>
</div>
<form method="post">
    <div class="row">
        <div class="col-4">Повар:</div>
        <div class="col-8"><select id="Id" name="Id" class="form-control" onchange="populateFields()" asp-items="@(new SelectList(@ViewBag.CookList, "Id", "FIO"))"></select></div>
    </div>
    <div class="row">
        <div class="col-4">ФИО:</div>
        <div class="col-8"><input type="text" name="FIO" value="" /></div>
    </div>
    <div class="row">
        <div class="col-4">Должность:</div>
        <div class="col-8"><input type="text" name="position" value="" /></div>
    </div>
    <div class="row">
        <div class="col-8"></div>
        <div class="col-4"><input type="submit" value="Сохранить" class="btn btn-primary" /></div>
    </div>
</form>
<script>
    const cooks = [];

    function populateFields() {
        ViewBag.CookList.forEach(value => {
            cooks.push(value);
        });
        var selectedCookId = document.getElementById("Id").value;
        var selectedCook = cooks.find(function (cook) {
            return cook.Id === selectedCookId;
        });
        //console.log(selectedCook.FIO);
        if (selectedCook) {
            document.getElementsByName("FIO")[0].value = selectedCook.FIO;
            document.getElementsByName("position")[0].value = selectedCook.Position;
        }
        console.log(document.getElementsByName("FIO")[0].value);
    }
</script>