我想为
HtmlHelperLabelForpublic class Foo
{
[Required]
public string Name { get; set; }
}
Html.LabelFor(o => o.Name) // Name*
您可以纯粹通过 CSS 将星号添加到必填字段。
首先，为其创建一个 CSS 类：
.required::after
{
content: "*";
font-weight: bold;
color: red;
}
这将为任何具有“required”类的元素附加一个红色星号。
然后，在您看来，只需将新类添加到您的标签中即可：
@Html.LabelFor(m => m.Name, new { @class="required" })
更好的可能是自定义 HTML Helper，它可以识别字段是否具有 [Required] 属性，如果有，则添加
required这里有一篇博客文章描述了如何执行此操作。
给你一个从上面的网站修改的小例子（注意 - 我还没有编译/测试这个）：
namespace HelpRequest.Controllers.Helpers
{
public static class LabelExtensions
{
public static MvcHtmlString Label(this HtmlHelper html, string expression, string id = "", bool generatedId = false)
{
return LabelHelper(html, ModelMetadata.FromStringExpression(expression, html.ViewData), expression, id, generatedId);
}
[SuppressMessage("Microsoft.Design", "CA1006:DoNotNestGenericTypesInMemberSignatures", Justification = "This is an appropriate nesting of generic types")]
public static MvcHtmlString LabelFor<TModel, TValue>(this HtmlHelper<TModel> html, Expression<Func<TModel, TValue>> expression, string id = "", bool generatedId = false)
{
return LabelHelper(html, ModelMetadata.FromLambdaExpression(expression, html.ViewData), ExpressionHelper.GetExpressionText(expression), id, generatedId);
}
internal static MvcHtmlString LabelHelper(HtmlHelper html, ModelMetadata metadata, string htmlFieldName, string id, bool generatedId)
{
string labelText = metadata.DisplayName ?? metadata.PropertyName ?? htmlFieldName.Split('.').Last();
if (String.IsNullOrEmpty(labelText))
{
return MvcHtmlString.Empty;
}
var sb = new StringBuilder();
sb.Append(labelText);
if (metadata.IsRequired)
sb.Append("*");
var tag = new TagBuilder("label");
if (!string.IsNullOrWhiteSpace(id))
{
tag.Attributes.Add("id", id);
}
else if (generatedId)
{
tag.Attributes.Add("id", html.ViewContext.ViewData.TemplateInfo.GetFullHtmlFieldId(htmlFieldName) + "_Label");
}
tag.Attributes.Add("for", html.ViewContext.ViewData.TemplateInfo.GetFullHtmlFieldId(htmlFieldName));
tag.SetInnerText(sb.ToString());
return MvcHtmlString.Create(tag.ToString(TagRenderMode.Normal));
}
}
}
我这样做是因为我的必填字段必须是动态的（在配置文件中定义）
在视图末尾添加：
<script type="text/javascript">
$('input[type=text]').each(function () {
var req = $(this).attr('data-val-required');
if (undefined != req) {
var label = $('label[for="' + $(this).attr('id') + '"]');
var text = label.text();
if (text.length > 0) {
label.append('<span style="color:red"> *</span>');
}
}
});
</script>
这是我的解决方案，基于 Adam Tuliper 的答案，但经过修改以与 Bootstrap 一起使用，并且还允许使用 自定义属性。
using System;
using System.Linq;
using System.Web.Mvc;
using System.Linq.Expressions;
using System.ComponentModel;
public static class RequiredLabel
{
public static MvcHtmlString RequiredLabelFor<TModel, TValue>(this HtmlHelper<TModel> helper, Expression<Func<TModel, TValue>> expression, object htmlAttributes)
{
var metaData = ModelMetadata.FromLambdaExpression(expression, helper.ViewData);
string htmlFieldName = ExpressionHelper.GetExpressionText(expression);
string labelText = metaData.DisplayName ?? metaData.PropertyName ?? htmlFieldName.Split('.').Last();
if (metaData.IsRequired)
labelText += "<span class=\"required\">*</span>";
if (String.IsNullOrEmpty(labelText))
return MvcHtmlString.Empty;
var label = new TagBuilder("label");
label.Attributes.Add("for", helper.ViewContext.ViewData.TemplateInfo.GetFullHtmlFieldId(htmlFieldName));
foreach (PropertyDescriptor prop in TypeDescriptor.GetProperties(htmlAttributes))
{
label.MergeAttribute(prop.Name.Replace('_', '-'), prop.GetValue(htmlAttributes).ToString(), true);
}
label.InnerHtml = labelText;
return MvcHtmlString.Create(label.ToString());
}
}
然后，我从我的角度这样称呼它：
@Html.RequiredLabelFor(model => model.Category, new { @class = "control-label col-md-3" })
附注确保您不要忘记在视图中包含您的命名空间。
请参阅此处的这篇文章 - 应该包含您需要的大部分内容 http://blogs.planetcloud.co.uk/mygreatdiscovery/post/Creating-tooltips-using-data-annotations-in-ASPNET-MVC.aspx
public static MvcHtmlString RequiredLabelFor<TModel, TValue>(this HtmlHelper<TModel> helper, Expression<Func<TModel, TValue>> expression)
{
var metaData = ModelMetadata.FromLambdaExpression(expression, helper.ViewData);
string htmlFieldName = ExpressionHelper.GetExpressionText(expression);
string labelText = metaData.DisplayName ?? metaData.PropertyName ?? htmlFieldName.Split('.').Last();
if (metaData.IsRequired)
labelText += "<span class=\"required-field\">*</span>";
if (String.IsNullOrEmpty(labelText))
return MvcHtmlString.Empty;
var label = new TagBuilder("label");
label.Attributes.Add("for", helper.ViewContext.ViewData.TemplateInfo.GetFullHtmlFieldId(htmlFieldName));
label.InnerHtml = labelText;
return MvcHtmlString.Create(label.ToString());
}
使用 helper 将样式类添加到标签
public static MvcHtmlString RequiredLabelFor<TModel, TValue>(this HtmlHelper<TModel> html, Expression<Func<TModel, TValue>> expression, object htmlAttributes)
{
var metadata = ModelMetadata.FromLambdaExpression(expression, html.ViewData);
var resolvedLabelText = metadata.DisplayName ?? metadata.PropertyName;
if (!metadata.IsRequired)
{
return html.LabelFor(expression, resolvedLabelText, htmlAttributes);
}
var attributes = HtmlHelper.AnonymousObjectToHtmlAttributes(htmlAttributes);
if (attributes == null)
{
return html.LabelFor(expression, resolvedLabelText, htmlAttributes);
}
const string requiredClass = "required-label";
if (attributes.ContainsKey("class"))
{
var classList = attributes["class"].ToString().Split(' ').ToList();
classList.Add(requiredClass);
attributes["class"] = string.Join(" ", classList);
}
else
{
attributes.Add("class", requiredClass);
}
return html.LabelFor(expression, resolvedLabelText, attributes);
}
然后你可以设计类的样式：
.required-label::after { content : "*" }
我从其他一些帖子中将其整合在一起：
它对我有用，因为 labelfor 后面跟着一个输入加上一个范围（标签所属的输入和验证范围）
input[data-val-required]+span:before {
content: "*";
font-weight: bold;
color: red;
position:relative;
top:-34px;
left:-12px;
font-size:14pt;
}
虽然这不需要修改 LabelFor，但这是我能想到的最简单的，只需要 ViewModel 中的 1 行：
public class FooViewModel
{
[Required(ErrorMessage = "Name is required")]
[Display(Name ="Name*")]
public string Name { get; set; }
}
Html.LabelFor(o => o.Name)
根据 Renato Saito 的上述回答以及评论，以及添加 $(document).ready 并检查以确保我们没有添加多个星号（我在我的一些字段中得到了这一点）出于某种原因），我有这个：
// Add asterisks to required fields
$(document).ready(function() {
$("[data-val-required]").each(function () {
var label = $('label[for="' + $(this).attr("id") + '"]');
var asterisksHtml = '<span style="color:red"> *</span>';
if (label.text().length > 0 && label.html().indexOf(asterisksHtml) === -1) {
label.append(asterisksHtml);
}
});
});
在具有多种字段类型的 MVC 中最适合我
$('input[type=text], input[type=password], input[type=email], input[type=tel], select').each(function () {
var req = $(this).attr('data-val-required');
if (undefined != req) {
var label = $('label[for="' + $(this).attr('name') + '"]');
var text = label.text();
if (text.length > 0) {
label.append('<span style="color:red"> *</span>');
}
}
});使用保留内部化/翻译标签和 html 属性的辅助扩展在必填字段（通过数据注释定义 [必需]）后添加装饰字形图标
1。创建文件夹“Helpers”并添加新控制器“Helper.cs”
using System;
using System.ComponentModel;
using System.Linq;
using System.Linq.Expressions;
using System.Web.Mvc;
namespace WIPRO.Helpers
{
public static class Helpers
{
public static MvcHtmlString LabelForRequired<TModel, TValue>(this HtmlHelper<TModel> helper, Expression<Func<TModel, TValue>> expression, string translatedlabelText, object htmlAttributes)
{
var metaData = ModelMetadata.FromLambdaExpression(expression, helper.ViewData);
string htmlFieldName = ExpressionHelper.GetExpressionText(expression);
string labelText = metaData.DisplayName ?? metaData.PropertyName ?? htmlFieldName.Split('.').Last();
if (metaData.IsRequired)
{
labelText = translatedlabelText + "<span class=\"required\" style=\"color:orange;\"> <span style=\"font-size: 0.4em; vertical-align: super;\" class=\"glyphicon glyphicon-asterisk\" data-unicode=\"270f\"></span></span>";
}
else
{
labelText = translatedlabelText;
}
if (String.IsNullOrEmpty(labelText))
return MvcHtmlString.Empty;
var label = new TagBuilder("label");
label.Attributes.Add("for", helper.ViewContext.ViewData.TemplateInfo.GetFullHtmlFieldId(htmlFieldName));
foreach (PropertyDescriptor prop in TypeDescriptor.GetProperties(htmlAttributes))
{
label.MergeAttribute(prop.Name.Replace('_', '-'), prop.GetValue(htmlAttributes).ToString(), true);
}
label.InnerHtml = labelText;
return MvcHtmlString.Create(label.ToString());
}
}
}
2。在你看来
@using WIPRO.Helpers
@Html.LabelForRequired(model => model.Test,"Translated text", htmlAttributes: new { @class = "control-label col-md-2" })
代替
@Html.LabelFor(model => model.Test,"Translated text", htmlAttributes: new { @class = "control-label col-md-2" })
希望有帮助;-)
发布通用解决方案：
以下是使用 Bootstrap 的通用格式：
<div class="form-group row">
<label class="col-md-3 label-control" asp-for="FacilityCode"></label>
<div class="col-md-9">
<input asp-for="FacilityCode" class="form-control" placeholder="@Localizer["Facility Code"]" />
<span asp-validation-for="FacilityCode" class="text-danger"></span>
</div>
</div>
这里是TagHelper默认生成的代码：
<div class="form-group row">
<label class="col-md-3 label-control" for="FacilityCode">Example Label </label>
<div class="col-md-9">
<input class="form-control" placeholder="Facility Code" type="text" data-val="true" data-val-length="The field Institution (Community) must be a string with a maximum length of 5." data-val-length-max="5" data-val-required="The Institution (Community) field is required." id="FacilityCode" maxlength="5" name="FacilityCode" value="12345">
<span class="text-danger field-validation-valid" data-valmsg-for="FacilityCode" data-valmsg-replace="true"></span>
</div>
</div>
我需要的是将
<span style="color:red;">*</span>TagHelper// append red star to required fields
$(document).ready(function () {
$('input[data-val-required]')
.closest(".form-group")
.find("label.label-control")
.append("<span style='color:red;'>*</span>");
});
我想创建一个在需要属性时显示星号的标签。但不知何故，即使
metadata.IsRequired[Required]AssociatedMetadataTypeTypeDescriptionProviderpublic static MvcHtmlString CustomLabelFor<TModel, TValue>(this HtmlHelper<TModel> htmlHelper, Expression<Func<TModel, TValue>> expression, object htmlAttributes = null)
{
ModelMetadata metadata = ModelMetadata.FromLambdaExpression(expression, htmlHelper.ViewData);
var descriptor = new AssociatedMetadataTypeTypeDescriptionProvider(metadata.ContainerType).GetTypeDescriptor(metadata.ContainerType).GetProperties().Find(metadata.PropertyName, true);
var required = (new List<Attribute>(descriptor.Attributes.OfType<Attribute>())).OfType<RequiredAttribute>().FirstOrDefault();
//get the normal labelfor
var label = htmlHelper.LabelFor(expression, htmlAttributes);
//create the extra span with the asterix in there is a required property
if (required != null)
{
var span = new TagBuilder("span");
span.MergeAttribute("class", "text-danger font-weight-bold");
//render the span
StringBuilder sb = new StringBuilder();
sb.Append(span.ToString(TagRenderMode.StartTag));
sb.Append("*");
sb.Append(span.ToString(TagRenderMode.EndTag));
return MvcHtmlString.Create(label.ToHtmlString() + " " + sb.ToString());
}
else
{
return label;
}
}
用法
@Html.CustomLabelFor(m => m.Title)
我正在与
TagHelperusing Microsoft.AspNetCore.Mvc.Rendering;
using Microsoft.AspNetCore.Mvc.ViewFeatures;
using Microsoft.AspNetCore.Razor.TagHelpers;
namespace MyTestProject.Helpers;
[HtmlTargetElement("label", Attributes = "asp-for")]
public class RequiredFieldTagHelper : TagHelper
{
public override int Order => 1;
[HtmlAttributeName("asp-for")]
public ModelExpression For { get; set; }
public override void Process(TagHelperContext context, TagHelperOutput output)
{
ArgumentNullException.ThrowIfNull(context);
ArgumentNullException.ThrowIfNull(output);
var metadata = For.Metadata;
var isRequired = metadata.ValidatorMetadata
.Any(m => m is RequiredAttribute);
if (isRequired)
{
var asterisk = new TagBuilder("span");
asterisk.AddCssClass("text-danger required-field-marker");
asterisk.InnerHtml.Append("*");
output.PostContent.AppendHtml(asterisk);
}
}
}
完成后，我们可以将
AssemblyName_ViewImports.cshtmlMyTestProject<AssemblyName>@addTagHelper *, MyTestProject
我们也可以添加 CSS 更改
.required-field-marker {
margin-left: 4px;
color: firebrick;
}
.required-field-note {
color: rgba(255, 255, 255, 0.6);
font-size: 0.75rem;
font-style: italic;
}