枚举 – 使用MVC6标记助手为Enum添加单个标签的单选按钮

2019年7月27日 210次阅读

我的模型包含一个枚举,我正在尝试绑定到一个单选按钮列表,这样在提交表单时只能选择一个值.

public enum Options
{
    [Display(Name="Option A")
    OptionA,
    [Display(Name="Option B")
    OptionB
}

public class MyModel
{
     public Options SelectedOption {get; set;}
     public string TextA{get; set;}
     public string TextB{get; set;}
}

在MVC 5中,我将为每个枚举值渲染一个单选按钮输入,用户只能选择一个.因此,每个单选按钮的视图中的代码可能如下所示：

@Html.RadioButtonFor(m => m.SelectedOption, Options.OptionA)

MVC6的问题似乎是输入标记帮助器不支持开箱即用的枚举属性.因此,如果我尝试添加< input asp-for =“SelectedOption”/>,我得到的只是一个文本框.

所以我的问题是,有没有办法使用MVC6标签帮助程序(开箱即用或自定义)或是否有另一种方法来做到这一点？也许类似于使用旧的剃刀语法或只是添加输入标签并填充其属性？

请注意,理想情况下,两个单选按钮都必须有标签,以显示枚举[Display]属性中指定的文本.此外,只有一个TextA或TextB文本框可以同时出现,这应该基于所选的单选按钮,但这超出了问题的范围.所以这里是渲染标记的样子(或多或少)：

<div>
    <div>
        <input id="OptionA" type="radio" name="SelectedOption"/>
        <label for="OptionA">Option A</label>
    </div>
    <div>
        <label for="TextA">Text A</label>
        <input type="text" id="TextA" name="TextA">
    </div>
<div>

<div>
<div>
    <input id="OptionB" type="radio" name="SelectedOption"/>
    <label for="OptionB">Option B</label>
</div>

    <div>
        <label for="TextB">Text A</label>
        <input type="text" id="TextB" name="TextB">
    </div>
<div>

最佳答案

<enum-radio-button asp-for="ThisEnum"></enum-radio-button>
<enum-radio-button asp-for="ThisEnum" value="ThisEnum.Value001"></enum-radio-button>

ThisEnum.Value001 = Auto Checked radio input..

用于枚举单选按钮列表的Asp.Net Core TagHelper

/// <summary>
/// <see cref="ITagHelper"/> implementation targeting &lt;enum-radio-button&gt; elements with an <c>asp-for</c> attribute, <c>value</c> attribute.
/// </summary>
[HtmlTargetElement("enum-radio-button", Attributes = RadioButtonEnumForAttributeName)]
public class RadioButtonEnumTagHelper : TagHelper
{
    private const string RadioButtonEnumForAttributeName = "asp-for";
    private const string RadioButtonEnumValueAttributeName = "value";

    /// <summary>
    /// Creates a new <see cref="RadioButtonEnumTagHelper"/>.
    /// </summary>
    /// <param name="generator">The <see cref="IHtmlGenerator"/>.</param>
    public RadioButtonEnumTagHelper(IHtmlGenerator generator)
    {
        Generator = generator;
    }

    /// <inheritdoc />
    public override int Order => -1000;

    [HtmlAttributeNotBound]
    [ViewContext]
    public ViewContext ViewContext { get; set; }

    protected IHtmlGenerator Generator { get; }

    /// <summary>
    /// An expression to be evaluated against the current model.
    /// </summary>
    [HtmlAttributeName(RadioButtonEnumForAttributeName)]
    public ModelExpression For { get; set; }

    [HtmlAttributeName(RadioButtonEnumValueAttributeName)]
    public Enum value { get; set; }

    /// <inheritdoc />
    /// <remarks>Does nothing if <see cref="For"/> is <c>null</c>.</remarks>
    public override async Task ProcessAsync(TagHelperContext context, TagHelperOutput output)
    {

        var childContent = await output.GetChildContentAsync();
        string innerContent = childContent.GetContent();
        output.Content.AppendHtml(innerContent);

        output.TagName = "div";
        output.TagMode = TagMode.StartTagAndEndTag;
        output.Attributes.Add("class", "btn-group btn-group-radio");

        if (context == null)
        {
            throw new ArgumentNullException(nameof(context));
        }

        if (output == null)
        {
            throw new ArgumentNullException(nameof(output));
        }

        var modelExplorer = For.ModelExplorer;
        var metaData = For.Metadata;

        if (metaData.EnumNamesAndValues != null)
        {
            foreach (var item in metaData.EnumNamesAndValues)
            {
                string enum_id = $"{metaData.ContainerType.Name}_{metaData.PropertyName}_{item.Key}";

                bool enum_ischecked = false;
                if (value != null)
                {
                    if (value != null && item.Key.ToString() == value.ToString())
                    {
                        enum_ischecked = true;
                    }
                }
                else
                {
                    if (For.Model != null && item.Key.ToString() == For.Model.ToString())
                    {
                        enum_ischecked = true;
                    }
                }

                string enum_input_label_name = item.Key;
                var enum_resourced_name = metaData.EnumGroupedDisplayNamesAndValues.Where(x => x.Value == item.Value).FirstOrDefault();
                if (enum_resourced_name.Value != null)
                {
                    enum_input_label_name = enum_resourced_name.Key.Name;
                }

                var enum_radio = Generator.GenerateRadioButton(
                    ViewContext,
                    For.ModelExplorer,
                    metaData.PropertyName,
                    item.Key,
                    false,
                    htmlAttributes: new { @id = enum_id });
                enum_radio.Attributes.Remove("checked");
                if (enum_ischecked)
                {
                    enum_radio.MergeAttribute("checked", "checked");
                }
                output.Content.AppendHtml(enum_radio);

                var enum_label = Generator.GenerateLabel(
                    ViewContext,
                    For.ModelExplorer,
                    For.Name,
                    enum_input_label_name,
                    htmlAttributes: new { @for = enum_id, @Class = "btn btn-default" });
                output.Content.AppendHtml(enum_label);
            }
        }
    }
}

I’m using this style

Html result

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