Html 在asp.core razor页面中设置所选项目

我正在使用ASP核心剃须刀页面。 这是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 },

            };

@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>

[BindProperty]
公共列表ccuser{get；set；}
在这里，我用数据填充CCusers：
CCusers=新列表（）{
新建Microsoft.AspNetCore.Mvc.Rendering.SelectListItem（）{Value=“1”，Text=“HR”，Selected=true}，
新建Microsoft.AspNetCore.Mvc.Rendering.SelectListItem（）{Value=“2”，Text=“IT”，Selected=false}，
新建Microsoft.AspNetCore.Mvc.Rendering.SelectListItem（）{Value=“3”，Text=“Account”，Selected=false}，
};

在Razor页面中，我使用了两种不同的选择：

    <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" })

@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>

//这是：
@Html.DropDownList（“NewSelect”，Model.CCusers，new{@class=“selectpicker”，@multiple=“multiple”}）

这是他们两人的结果：

<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>

@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>

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核心选择没有设置所选项目，而@Httml.DropDownList设置了该项目。 我在第一次选择中缺少什么？

对于，您需要为设置

asp，它指定
选择
元素的模型属性名称

@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>

对于您的问题，您需要为所选的
CCusers
定义新属性，而不是直接将
CCusers
绑定到
asp For

@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>

您可以参考以下代码：

@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>

页面

    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");
    }
}

@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>

公共类EditModel:PageModel
{
[BindProperty]
public int[]selectedCCUserID{get；set；}
[BindProperty]
公共列表ccuser{get；set；}
公共互联网
{
SelectedCCuserIds=newint[]{1,2}；
CCusers=新列表（）{
新建SelectListItem（）{Value=“1”，Text=“HR”}，
新建SelectListItem（）{Value=“2”，Text=“IT”}，
新建SelectListItem（）{Value=“3”，Text=“Account”}，
};
}
public IActionResult OnPost（）
{
var结果=选择的CCUserID；
返回重定向到操作（“OnGet”）；
}
}

看法

@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>

@page
@模型CoreRazor.Pages.EditModel
@{
ViewData[“标题”]=“编辑”；
}
编辑
@*@DropDownList（“NewSelect”，Model.CCusers，new{@class=“selectpicker”，
@multiple=“multiple”}）*@

您可能需要为

属性使用

asp。请参阅“谢谢”，我已经使用过它。在上面的链接中，它类似于asp for=“@Model.CCuserIds”

——有关更多详细信息，请参阅上面链接中的多个选择部分。

@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>