Set selected items in asp.core razor pages - html

Question

I'm using ASP Core Razor pages.
This my Edit.cshtml.cs:
[BindProperty]
public List<Microsoft.AspNetCore.Mvc.Rendering.SelectListItem> CCusers { get; set; }
and here I fill CCusers with data:
CCusers =new List<Microsoft.AspNetCore.Mvc.Rendering.SelectListItem>() {
new Microsoft.AspNetCore.Mvc.Rendering.SelectListItem() { Value = "1", Text = "HR", Selected = true },
new Microsoft.AspNetCore.Mvc.Rendering.SelectListItem() { Value = "2", Text = "IT", Selected = false },
new Microsoft.AspNetCore.Mvc.Rendering.SelectListItem() { Value = "3", Text = "Account", Selected = false },
};
In Razor Page, I used two different select:
<select asp-for="CCusers" asp-items="#Model.CCusers" id="CCusers" multiple="multiple" class="selectpicker"> </select>
//and this:
#Html.DropDownList("NewSelect", Model.CCusers, new { #class = "selectpicker", #multiple = "multiple" })
and this the result of both of them:
<select id="CCusers" multiple="multiple" class="selectpicker" name="CCusers">
<option value="1">HR</option>
<option value="2">IT</option>
<option value="3">Account</option>
</select>
<select class="selectpicker" id="NewSelect" multiple="multiple" name="NewSelect">
<option selected="selected" value="1">HR</option>
<option value="2">IT</option>
<option value="3">Account</option>
</select>
The Core Select didn't set the selected item while the #Httml.DropDownList did it.
What I'm missing in the first select?

Answer 1

For Select Tag Helper, you will need to set asp-for which specifies the model proprety name for the select element.
For your issue, you need to define new property for selected CCusers instead of binding the CCusers to asp-for directly.
You could refer code below:
Page
public class EditModel : PageModel
{
[BindProperty]
public int[] SelectedCCuserIds { get; set; }
[BindProperty]
public List<SelectListItem> CCusers { get; set; }
public void OnGet()
{
SelectedCCuserIds = new int[] { 1, 2 };
CCusers = new List<SelectListItem>() {
new SelectListItem() { Value = "1", Text = "HR" },
new SelectListItem() { Value = "2", Text = "IT" },
new SelectListItem() { Value = "3", Text = "Account" },
};
}
public IActionResult OnPost()
{
var result = SelectedCCuserIds;
return RedirectToAction("OnGet");
}
}
View
#page
#model CoreRazor.Pages.EditModel
#{
ViewData["Title"] = "Edit";
}
<h2>Edit</h2>
<form method="post">
<select asp-for="#Model.SelectedCCuserIds" asp-items="#Model.CCusers"
multiple="multiple" class="selectpicker"> </select>
#*#Html.DropDownList("NewSelect", Model.CCusers, new { #class = "selectpicker",
#multiple = "multiple" })*#
<div class="form-group">
<input type="submit" value="Save" class="btn btn-default" />
</div>