Set all checkbox in Kendo Dropdowntree checked when load the page - checkbox

Question

I want to create kendo dropdowntree where when i load the page, all the checkbox is checked. Here is my code.
#(Html.Kendo().DropDownTree()
.AutoWidth(true)
.Name("dropdowntree")
.DataTextField("Name")
.DataValueField("Id")
.CheckAll(true)
.HtmlAttributes(new { style = "width: 100%" })
.Events(events => events.Change("onChange"))
.Filter(FilterType.Contains)
.AutoClose(false)
.Checkboxes(checkboxes => checkboxes
.Name("checkedFiles")
.CheckChildren(true)
)
.DataSource(dataSource => dataSource
.Read(read => read
.Action("GetName", "CheckBox")
)
)
)
I already doing some research and try the solution, but none if them work. For example, what i have try:
$(document).ready(function () {
$("#dropdowntree input.k-checkbox").prop("checked", true);
})
This one also not work:
$(document).ready(function () {
$("#dropdowntree").attr('checked', 'checked');
})
This one is work, but i need to set the value. What i need is it checked all by default, no need to set the value.
$(document).ready(function () {
var dropdowntree = $("#dropdowntree").data("kendoDropDownTree");
dropdowntree.value(["1","2","3","4","5","6","7"]);
})
Other than all of these, i also try the solution in this link jquery set all checkbox checked and others solution. But still not work. I really need some advice. Thank you.

Answer 1

I already found the answer if there is someone need it.
First in controller i get all of the list for id, then i change the list into string in json.
CONTROLLER CODE:
public IActionResult CheckBoxDB()
{
List<string> parts = new List<string>();
GetId(parts);
ViewBag.All = parts;
var json = JsonConvert.SerializeObject(parts);
ViewBag.change = json;
return View();
}
private void GetId(List<string> parts)
{
List<DdlcheckBox> ddlcheckBoxes = new List<DdlcheckBox>();
ddlcheckBoxes = _context.DdlcheckBox.ToList();
foreach (var data in ddlcheckBoxes)
{
string id = data.Id.ToString();
parts.Add(id);
}
}
Then, in the Views, i get the ViewBag value at the script.
<script>
$(document).ready(function () {
var dropdowntree = $("#dropdowntree").data("kendoDropDownTree");
dropdowntree.value('#ViewBag.change');
});
</script>
Thank you.