如何在 .NET Core 中使用 EditorForMany Html 帮助程序

Question

Matt Lunn的EditorForMany html helper非常适合.NET Framework MVC，就像将无序数组回服务器一样。

如何使其适应 .NET Core？

Answer 1

以下是这个用于处理数组的宏伟 Html 助手的 .NET Core 版本的修改代码：

using Microsoft.AspNetCore.Html;
using Microsoft.AspNetCore.Mvc.Rendering;
using Microsoft.AspNetCore.Mvc.ViewFeatures.Internal;
using System;
using System.Collections.Generic;
using System.IO;
using System.Linq.Expressions;
using System.Net;
using System.Text;
using System.Text.Encodings.Web;
namespace VicEM.Extensions
{
public static class HtmlHelperExtensions
{
/// <summary>
/// Generates a GUID-based editor template, rather than the index-based template generated by Html.EditorFor()
/// </summary>
/// <typeparam name="TModel"></typeparam>
/// <typeparam name="TValue"></typeparam>
/// <param name="html"></param>
/// <param name="propertyExpression">An expression which points to the property on the model you wish to generate the editor for</param>
/// <param name="indexResolverExpression">An expression which points to the property on the model which holds the GUID index (optional, but required to make Validation* methods to work on post-back)</param>
/// <param name="includeIndexField">
/// True if you want this helper to render the hidden &lt;input /&gt; for you (default). False if you do not want this behaviour, and are instead going to call Html.EditorForManyIndexField() within the Editor view. 
/// The latter behaviour is desired in situations where the Editor is being rendered inside lists or tables, where the &lt;input /&gt; would be invalid.
/// </param>
/// <returns>Generated HTML</returns>
public static IHtmlContent EditorForMany<TModel, TValue>(this IHtmlHelper<TModel> html,
Expression<Func<TModel, IEnumerable<TValue>>> propertyExpression,
Expression<Func<TValue, string>> indexResolverExpression = null, bool includeIndexField = true)
where TModel : class
{
var items = propertyExpression.Compile()(html.ViewData.Model);
var htmlBuilder = new StringBuilder();
var htmlFieldName = ExpressionHelper.GetExpressionText(propertyExpression);
var htmlFieldNameWithPrefix = html.ViewData.TemplateInfo.GetFullHtmlFieldName(htmlFieldName);
Func<TValue, string> indexResolver;
if (indexResolverExpression == null)
{
indexResolver = x => null;
}
else
{
indexResolver = indexResolverExpression.Compile();
}
foreach (var item in items)
{
var dummy = new { Item = item };
var guid = indexResolver(item);
var memberExp = Expression.MakeMemberAccess(Expression.Constant(dummy), dummy.GetType().GetProperty("Item"));
var singleItemExp = Expression.Lambda<Func<TModel, TValue>>(memberExp, propertyExpression.Parameters);
if (string.IsNullOrEmpty(guid))
{
guid = Guid.NewGuid().ToString();
}
else
{
guid = WebUtility.HtmlEncode(guid);
}
if (includeIndexField)
{
IHtmlContent indexHtml = _EditorForManyIndexField(htmlFieldNameWithPrefix, guid, indexResolverExpression);
AppendHtml(indexHtml, htmlBuilder);
}
IHtmlContent itemHtml = html.EditorFor(singleItemExp, null, $"{htmlFieldName}[{guid}]");
AppendHtml(itemHtml, htmlBuilder);
}
return new HtmlString(htmlBuilder.ToString());
}
private static void AppendHtml(IHtmlContent itemHtml, StringBuilder htmlBuilder)
{
StringWriter writer = new StringWriter();
itemHtml.WriteTo(writer, HtmlEncoder.Default);
htmlBuilder.Append(writer);
}
/// <summary>
/// Used to manually generate the hidden &lt;input /&gt;. To be used in conjunction with EditorForMany(), when "false" was passed for includeIndexField. 
/// </summary>
/// <typeparam name="TModel"></typeparam>
/// <param name="html"></param>
/// <param name="indexResolverExpression">An expression which points to the property on the model which holds the GUID index (optional, but required to make Validation* methods to work on post-back)</param>
/// <returns>Generated HTML for hidden &lt;input /&gt;</returns>
public static IHtmlContent EditorForManyIndexField<TModel>(this IHtmlHelper<TModel> html,
Expression<Func<TModel, string>> indexResolverExpression = null)
{
var htmlPrefix = html.ViewData.TemplateInfo.HtmlFieldPrefix;
var first = htmlPrefix.LastIndexOf('[');
var last = htmlPrefix.IndexOf(']', first + 1);
if (first == -1 || last == -1)
{
throw new InvalidOperationException(
"EditorForManyIndexField called when not in a EditorForMany context");
}
var htmlFieldNameWithPrefix = htmlPrefix.Substring(0, first);
var guid = htmlPrefix.Substring(first + 1, last - first - 1);
return _EditorForManyIndexField(htmlFieldNameWithPrefix, guid, indexResolverExpression);
}
private static IHtmlContent _EditorForManyIndexField<TModel>(string htmlFieldNameWithPrefix, string guid,
Expression<Func<TModel, string>> indexResolverExpression)
{
var htmlBuilder = new StringBuilder();
htmlBuilder.AppendFormat(@"<input type=""hidden"" name=""{0}.Index"" value=""{1}"" />",
htmlFieldNameWithPrefix, guid);
if (indexResolverExpression != null)
{
htmlBuilder.AppendFormat(@"<input type=""hidden"" name=""{0}[{1}].{2}"" value=""{1}"" />",
htmlFieldNameWithPrefix, guid, ExpressionHelper.GetExpressionText(indexResolverExpression));
}
return new HtmlString(htmlBuilder.ToString());
}
}
}