Question

我正在尝试将未知数量的复选框绑定到布尔列表中。经过几个小时的搜索，我找不到任何解决方案。

在我看来，这是代码的相关部分：

        @foreach (Device d in Data.GetDevices())
    {
        <label asp-for="NewRegistration.Devices">@d.Name</label>
        <input asp-for="NewRegistration.Devices" class="checkbox" type="checkbox" />
    }

循环有效但当我改变了类型时，如果输入复选框，它给了我这个例子：

InvalidOperationException：意外的'asp-for'表达式结果类型'System.Collections.Generic.List`1 [[System.Boolean，System.Private.CoreLib，Version = 4.0.0.0，Culture = neutral，PublicKeyToken = 7cec85d7bea7798e] ]'为。如果'type'是'checkbox'，'asp-for'必须是'System.Boolean'类型。

我尝试将数据放入的列表包含以下代码：

        private List<bool> _devices;

    public List<bool> Devices
    {
        get { return _devices; }
        set {_devices = value; }
    }

所以我的问题是如何将这些复选框中的值添加到我的布尔值列表中。当我没有指定输入的类型时，我没有得到任何错误，但输入的类型是文本。如果我在这些输入框中输入true或false，我的代码工作正常。但我想要一个复选框，而不是要求用户输入true或false。

感谢您的时间！

编辑：我的问题很难解释。我正在验证表单并将其绑定到演示模型PMRegistration中定义的注册类的实例。如果片段不够清晰，我会在下面填写完整的代码

注册课程：

  public class Registration
{

    public int Id { get; set; }
    [Required(ErrorMessage = "required field")]
    [MaxLength(50, ErrorMessage = "To long")]
    [DisplayName("Name")]
    public string Name { get; set; }
    [Required(ErrorMessage = "required field")]
    [MaxLength(50, ErrorMessage = "To long")]
    [DisplayName("Firstname")]
    public string FirstName { get; set; }
    [Required(ErrorMessage = "required field")]
    [Range(1,110 ,ErrorMessage = "To long")]

    public string Age { get; set; }
    [Required(ErrorMessage = "required field")]
    [EmailAddress(ErrorMessage ="Not a valid email address")]
    public string Email { get; set; }
    [Required(ErrorMessage = "required field")]
    [DisplayName("slot1")]
    public int Slot1SessionId { get; set; }
    [Required(ErrorMessage = "required field")]
    [DisplayName("slot2")]
    public int Slot2SessionId { get; set; }
    [Required(ErrorMessage = "required field")]
    [DisplayName("slot3")]
    public int Slot3SessionId { get; set; }


    private List<bool> _devices;

    public List<bool> Devices
    {
        get { return _devices; }
        set {_devices = value; }
    }

    [Required(ErrorMessage = "required field")]
    [DisplayName("Organization")]
    public int OrganizationId { get; set; }
    public bool ClosingParty { get; set; }



}

我的观点如下：

        @using week3.Models;
@model week3.Models.PresentationModels.PMRegistration
<div>
    <h1>New Registration</h1>
    <h2>registration</h2>
</div>
<form class="form-group" asp-controller="Registration" asp-action="New" method="post">
    <div>
        <label asp-for="NewRegistration.Name">Name:</label>
        <input asp-for="NewRegistration.Name" class="form-control" value="@Model.NewRegistration.Name" />
        <span asp-validation-for="NewRegistration.Name" class="text-danger"></span>
    </div>
    <div>
        <label asp-for="NewRegistration.FirstName">Firstname:</label>
        <input asp-for="NewRegistration.FirstName" class="form-control" value="@Model.NewRegistration.FirstName" />
        <span asp-validation-for="NewRegistration.FirstName" class="text-danger"></span>
    </div>
    <div>
        <label asp-for="NewRegistration.Age">Age:</label>
        <input asp-for="NewRegistration.Age" class="form-control" value="@Model.NewRegistration.Age" />
        <span asp-validation-for="NewRegistration.Age" class="text-danger"></span>
    </div>
    <div>
        <label asp-for="NewRegistration.Email">Email:</label>
        <input asp-for="NewRegistration.Email" class="form-control" value="@Model.NewRegistration.Email" />
        <span asp-validation-for="NewRegistration.Email" class="text-danger"></span>
    </div>
    <div>
        <div>Pick your sessions</div>
        <label asp-for="NewRegistration.Slot1SessionId" class="form-label">Slot1:</label>
        <select asp-for="NewRegistration.Slot1SessionId" class="form-control" asp-items="@Model.getSessionNamesBySlot(1)" value="@Model.NewRegistration.Slot1SessionId"></select>
        <span asp-validation-for="NewRegistration.Slot1SessionId" class="text-danger"></span>
    </div>
    <div>
        <label asp-for="NewRegistration.Slot2SessionId">Slot2:</label>
        <select asp-for="NewRegistration.Slot2SessionId" class="form-control" asp-items="@Model.getSessionNamesBySlot(2)" value="@Model.NewRegistration.Slot2SessionId"></select>
        <span asp-validation-for="NewRegistration.Slot2SessionId" class="text-danger"></span>
    </div>
    <div>
        <label asp-for="NewRegistration.Slot3SessionId">Slot3:</label>
        <select asp-for="NewRegistration.Slot3SessionId" class="form-control" asp-items="@Model.getSessionNamesBySlot(3)" value="@Model.NewRegistration.Slot3SessionId"></select>
        <span asp-validation-for="NewRegistration.Slot3SessionId" class="text-danger"></span>
    </div>
    
        <div>are you wearing dangerous accessoires?</div>

        @foreach (Device d in Data.GetDevices())
        {
            
            <label asp-for="NewRegistration.Devices[0]">@d.Name</label>
            <input asp-for="NewRegistration.Devices[0]" class="checkbox" type="checkbox"  />
        }
    <div>
        <label asp-for="NewRegistration.OrganizationId">Organization:</label>
        <select asp-for="NewRegistration.OrganizationId" asp-items="@Model.getOrganizations()" class="form-control"></select><br />
    <span asp-validation-for="NewRegistration.OrganizationId" class="text-danger"></span>
    </div>
    <div>
        <label asp-for="NewRegistration.ClosingParty">Are you coming to the closing party?</label>
        <input asp-for="NewRegistration.ClosingParty" />
        <span asp-validation-for="NewRegistration.ClosingParty" class="text-danger"></span>
    </div>
            <input type="submit" class="btn btn-default" value="Register" />
</form>

Answer 1

错误原因

您的错误是因为您拥有：asp-for="NewRegistration.Devices"。这是无效的，因为标签是类型复选框的输入，所以asp-for期待一个布尔值，你发送一个布尔列表。

<强>解决方案

这将为您的设备创建复选框：

@foreach (Device d in Data.GetDevices())
{
    @Html.CheckBox(item);
}

但我的假设是你希望用户选择这些复选框，然后将它们发回给你，如果是这种情况那么你需要这样做：

您需要创建一个这样的模型：

public class Device
{
    public string Name { get; set; }
}
public class DevicesCollectionModel
{
    public List<Device> AvailableDevices { get; set; }
    public List<Device> SelectedDevices { get; set; }
}

填充DevicesCollectionModel.AvailableDevices并将其传递给您的视图。然后在您的视图中，为AvailableDevices中的每个设备创建一个复选框。请注意以下输入标记的name属性：

@foreach (var item in Model.AvailableDevices)
{
<div class="checkbox">
    <label>
        <input type="checkbox"
                name="SelectedDevices"
                value="@item.Name" /> @item.Name
        </label>
    </div>
}

然后在您的控制器中，在帖子中，您需要访问SelectedDevices属性以确定用户选择的内容。

此外，您可以创建单独的模型：一个用于发送给用户，另一个用于控制器从用户接收。您传递到视图的模型可以只有AvailableDevices，而您在控制台上获得的模型可以有SelectedDevices。 MVC将使用输入标记中的name属性为您绑定它。

Asp.net MVC将复选框数据放入布尔值列表中

1 个答案: