我修改了@Alexander Puchkov 的答案，以便自动创建一个 ExtendedSelectList，其中包含一组 ExtendedSelectListItems，该集合是从传递给它的 Items 的属性自动生成的，而无需手动指定每个 SelectListItem 的属性。它将属性创建为“data-*”。您可以使用函数 parms 或将它们列在 excludeProperties 中来排除某些属性。
using System;
using System.Collections;
using System.Collections.Generic;
using System.Globalization;
using System.Linq;
using System.Linq.Expressions;
using System.Reflection;
using System.Text;
using System.Web;
using System.Web.Mvc;
using System.Web.UI;
namespace App.Infrastructure.Helpers.Extensions
{
public class ExtendedSelectList : SelectList
{
static readonly string[] excludedProperties = new string[] { "DateInsert", "DateUpdate" }; // Write here properties you want to exclude for every ExtendedSelectList
public ICollection<ExtendedSelectListItem> ExtendedSelectListItems { get; set; }
public ExtendedSelectList(IEnumerable items, string dataValueField, string dataTextField, object selectedValue, params string[] exclude) : base(items, dataValueField, dataTextField, selectedValue)
{
ExtendedSelectListItems = new List<ExtendedSelectListItem>();
exclude = exclude.Concat(new string[] { dataValueField, dataTextField }).ToArray();
exclude = exclude.Concat(excludedProperties).ToArray();
foreach (var selectListItem in this.AsEnumerable())
{
var extendedItem = new ExtendedSelectListItem() { Value = selectListItem.Value, Text = selectListItem.Text, Selected = selectListItem.Selected, Disabled = selectListItem.Disabled, Group = selectListItem.Group };
var htmlAttributes = new Dictionary<string, object>();
var item = items.Cast<object>().FirstOrDefault(x =>
{
string valueItem = DataBinder.Eval(x, DataValueField).ToString();
string valueSelectListItem = DataBinder.Eval(selectListItem, "Value").ToString();
return valueItem == valueSelectListItem;
});
foreach (PropertyInfo property in item.GetType().GetProperties())
{
if (!property.CanRead || (property.GetIndexParameters().Length > 0) || (exclude != null && exclude.Contains(property.Name)))
continue;
htmlAttributes.Add("data-" + property.Name.ToLower(), property.GetValue(item));
}
extendedItem.HtmlAttributesDict = htmlAttributes;
ExtendedSelectListItems.Add(extendedItem);
}
}
}
public class ExtendedSelectListItem : SelectListItem
{
public object HtmlAttributes { get; set; }
public Dictionary<string, object> HtmlAttributesDict { get; set; }
}
public static class ExtendedSelectExtensions
{
internal static object GetModelStateValue(this HtmlHelper htmlHelper, string key, Type destinationType)
{
System.Web.Mvc.ModelState modelState;
if (htmlHelper.ViewData.ModelState.TryGetValue(key, out modelState))
{
if (modelState.Value != null)
{
return modelState.Value.ConvertTo(destinationType, null /* culture */);
}
}
return null;
}
public static MvcHtmlString ExtendedDropDownList(this HtmlHelper htmlHelper, string name, IEnumerable<ExtendedSelectListItem> selectList)
{
return ExtendedDropDownList(htmlHelper, name, selectList, (string)null, (IDictionary<string, object>)null);
}
public static MvcHtmlString ExtendedDropDownList(this HtmlHelper htmlHelper, string name, IEnumerable<ExtendedSelectListItem> selectList, string optionLabel, IDictionary<string, object> htmlAttributes)
{
return ExtendedDropDownListHelper(htmlHelper, null, name, selectList, optionLabel, htmlAttributes);
}
public static MvcHtmlString ExtendedDropDownListHelper(this HtmlHelper htmlHelper, ModelMetadata metadata, string expression, IEnumerable<ExtendedSelectListItem> selectList, string optionLabel, IDictionary<string, object> htmlAttributes)
{
return SelectInternal(htmlHelper, metadata, optionLabel, expression, selectList, false, htmlAttributes);
}
public static MvcHtmlString ExtendedDropDownListFor<TModel, TProperty>(this HtmlHelper<TModel> htmlHelper,
Expression<Func<TModel, TProperty>> expression, IEnumerable<ExtendedSelectListItem> selectList,
string optionLabel, object htmlAttributes)
{
if (expression == null)
throw new ArgumentNullException("expression");
ModelMetadata metadata = ModelMetadata.FromLambdaExpression<TModel, TProperty>(expression, htmlHelper.ViewData);
return SelectInternal(htmlHelper, metadata, optionLabel, ExpressionHelper.GetExpressionText(expression), selectList,
false /* allowMultiple */, HtmlHelper.AnonymousObjectToHtmlAttributes(htmlAttributes));
}
private static MvcHtmlString SelectInternal(this HtmlHelper htmlHelper, ModelMetadata metadata, string optionLabel, string name,
IEnumerable<ExtendedSelectListItem> selectList, bool allowMultiple,
IDictionary<string, object> htmlAttributes)
{
string fullName = htmlHelper.ViewContext.ViewData.TemplateInfo.GetFullHtmlFieldName(name);
if (String.IsNullOrEmpty(fullName))
throw new ArgumentException("No name");
if (selectList == null)
throw new ArgumentException("No selectlist");
object defaultValue = (allowMultiple)
? htmlHelper.GetModelStateValue(fullName, typeof(string[]))
: htmlHelper.GetModelStateValue(fullName, typeof(string));
// If we haven't already used ViewData to get the entire list of items then we need to
// use the ViewData-supplied value before using the parameter-supplied value.
if (defaultValue == null)
defaultValue = htmlHelper.ViewData.Eval(fullName);
if (defaultValue != null)
{
IEnumerable defaultValues = (allowMultiple) ? defaultValue as IEnumerable : new[] { defaultValue };
IEnumerable<string> values = from object value in defaultValues
select Convert.ToString(value, CultureInfo.CurrentCulture);
HashSet<string> selectedValues = new HashSet<string>(values, StringComparer.OrdinalIgnoreCase);
List<ExtendedSelectListItem> newSelectList = new List<ExtendedSelectListItem>();
foreach (ExtendedSelectListItem item in selectList)
{
item.Selected = (item.Value != null)
? selectedValues.Contains(item.Value)
: selectedValues.Contains(item.Text);
newSelectList.Add(item);
}
selectList = newSelectList;
}
// Convert each ListItem to an <option> tag
StringBuilder listItemBuilder = new StringBuilder();
// Make optionLabel the first item that gets rendered.
if (optionLabel != null)
listItemBuilder.Append(
ListItemToOption(new ExtendedSelectListItem()
{
Text = optionLabel,
Value = String.Empty,
Selected = false
}));
foreach (ExtendedSelectListItem item in selectList)
{
listItemBuilder.Append(ListItemToOption(item));
}
TagBuilder tagBuilder = new TagBuilder("select")
{
InnerHtml = listItemBuilder.ToString()
};
tagBuilder.MergeAttributes(htmlAttributes);
tagBuilder.MergeAttribute("name", fullName, true /* replaceExisting */);
tagBuilder.GenerateId(fullName);
if (allowMultiple)
tagBuilder.MergeAttribute("multiple", "multiple");
// If there are any errors for a named field, we add the css attribute.
System.Web.Mvc.ModelState modelState;
if (htmlHelper.ViewData.ModelState.TryGetValue(fullName, out modelState))
{
if (modelState.Errors.Count > 0)
{
tagBuilder.AddCssClass(HtmlHelper.ValidationInputCssClassName);
}
}
tagBuilder.MergeAttributes(htmlHelper.GetUnobtrusiveValidationAttributes(fullName, metadata));
return MvcHtmlString.Create(tagBuilder.ToString(TagRenderMode.Normal));
}
internal static string ListItemToOption(ExtendedSelectListItem item)
{
TagBuilder builder = new TagBuilder("option")
{
InnerHtml = HttpUtility.HtmlEncode(item.Text)
};
if (item.Value != null)
{
builder.Attributes["value"] = item.Value;
}
if (item.Selected)
{
builder.Attributes["selected"] = "selected";
}
var attributes = HtmlHelper.AnonymousObjectToHtmlAttributes(item.HtmlAttributes);
builder.MergeAttributes(attributes);
if (item.HtmlAttributesDict != null)
{
foreach (var attribute in item.HtmlAttributesDict)
{
var key = attribute.Key.ToLower(); // We call ToLower to keep the same naming convention used by MVC's HtmlHelper.AnonymousObjectToHtmlAttributes
var value = attribute.Value?.ToString() ?? "";
builder.Attributes[key] = value;
}
}
return builder.ToString(TagRenderMode.Normal);
}
}
}
要在 Razor 中使用它：
@{
var availableLocations = new ExtendedSelectList(Model.AvailableLocations, "Id", "Value", Model.LocationId);
}
@Html.ExtendedDropDownListFor(m => Model.LocationId, availableLocations.ExtendedSelectListItems, null, new { id = "ddLocation" })
请注意“availableLocations.ExtendedSelectListItems”，因为您不能直接使用 Enumerable 项目，因为它们是简单的 SelectListItem