Использование расширений MVC 4 в MVC 3

Question

Я хочу использовать Html.LabelFor() расширение Асп. Net MVC 4 для добавления атрибутов HTML к Label, Я использую MVC 3. Мой вопрос: могу ли я просто обновить свой system.web.mvc dll? (любая проблема с этим?...) ИЛИ это будет проблема в развертывании?

Answer 1

Это исходный код mvc3

internal static MvcHtmlString LabelHelper(HtmlHelper html, ModelMetadata metadata, string htmlFieldName, string labelText = null) {
string resolvedLabelText = labelText ?? metadata.DisplayName ?? metadata.PropertyName ?? htmlFieldName.Split('.').Last();
if (String.IsNullOrEmpty(resolvedLabelText)) {
    return MvcHtmlString.Empty;
}

TagBuilder tag = new TagBuilder("label");
tag.Attributes.Add("for", TagBuilder.CreateSanitizedId(html.ViewContext.ViewData.TemplateInfo.GetFullHtmlFieldName(htmlFieldName)));
tag.SetInnerText(resolvedLabelText);
return tag.ToMvcHtmlString(TagRenderMode.Normal);}

и это в mvc4

internal static MvcHtmlString LabelHelper(HtmlHelper html, ModelMetadata metadata, string htmlFieldName, string labelText = null, IDictionary<string, object> htmlAttributes = null){
string resolvedLabelText = labelText ?? metadata.DisplayName ?? metadata.PropertyName ?? htmlFieldName.Split('.').Last();
if (String.IsNullOrEmpty(resolvedLabelText))
{
    return MvcHtmlString.Empty;
}

TagBuilder tag = new TagBuilder("label");
tag.Attributes.Add("for", TagBuilder.CreateSanitizedId(html.ViewContext.ViewData.TemplateInfo.GetFullHtmlFieldName(htmlFieldName)));
tag.SetInnerText(resolvedLabelText);
tag.MergeAttributes(htmlAttributes, replaceExisting: true);
return tag.ToMvcHtmlString(TagRenderMode.Normal);}

есть только одна линия tag.MergeAttributes(htmlAttributes, replaceExisting: true);в mvc3 InputExtensions.cs вы можете найти функцию TagBuilder.MergeAttributes.
так что вы можете написать метод расширения самостоятельно, не нужно обновлять ваш проект.
ниже весь код в mvc4, может быть, это поможет вам

    // Copyright (c) Microsoft Corporation. All rights reserved. See License.txt in the project root for license information.

using System.Collections.Generic;
using System.Diagnostics.CodeAnalysis;
using System.Linq;
using System.Linq.Expressions;

namespace System.Web.Mvc.Html
{
    public static class LabelExtensions
    {
        public static MvcHtmlString Label(this HtmlHelper html, string expression)
        {
            return Label(html,
                         expression,
                         labelText: null);
        }

        public static MvcHtmlString Label(this HtmlHelper html, string expression, string labelText)
        {
            return Label(html, expression, labelText, htmlAttributes: null, metadataProvider: null);
        }

        public static MvcHtmlString Label(this HtmlHelper html, string expression, object htmlAttributes)
        {
            return Label(html, expression, labelText: null, htmlAttributes: htmlAttributes, metadataProvider: null);
        }

        public static MvcHtmlString Label(this HtmlHelper html, string expression, IDictionary<string, object> htmlAttributes)
        {
            return Label(html, expression, labelText: null, htmlAttributes: htmlAttributes, metadataProvider: null);
        }

        public static MvcHtmlString Label(this HtmlHelper html, string expression, string labelText, object htmlAttributes)
        {
            return Label(html, expression, labelText, htmlAttributes, metadataProvider: null);
        }

        public static MvcHtmlString Label(this HtmlHelper html, string expression, string labelText, IDictionary<string, object> htmlAttributes)
        {
            return Label(html, expression, labelText, htmlAttributes, metadataProvider: null);
        }

        internal static MvcHtmlString Label(this HtmlHelper html, string expression, string labelText, object htmlAttributes, ModelMetadataProvider metadataProvider)
        {
            return Label(html,
                         expression,
                         labelText,
                         HtmlHelper.AnonymousObjectToHtmlAttributes(htmlAttributes),
                         metadataProvider);
        }

        internal static MvcHtmlString Label(this HtmlHelper html, string expression, string labelText, IDictionary<string, object> htmlAttributes, ModelMetadataProvider metadataProvider)
        {
            return LabelHelper(html,
                               ModelMetadata.FromStringExpression(expression, html.ViewData, metadataProvider),
                               expression,
                               labelText,
                               htmlAttributes);
        }

        [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)
        {
            return LabelFor<TModel, TValue>(html, expression, labelText: null);
        }

        [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 labelText)
        {
            return LabelFor(html, expression, labelText, htmlAttributes: null, metadataProvider: null);
        }

        [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, object htmlAttributes)
        {
            return LabelFor(html, expression, labelText: null, htmlAttributes: htmlAttributes, metadataProvider: null);
        }

        [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, IDictionary<string, object> htmlAttributes)
        {
            return LabelFor(html, expression, labelText: null, htmlAttributes: htmlAttributes, metadataProvider: null);
        }

        [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 labelText, object htmlAttributes)
        {
            return LabelFor(html, expression, labelText, htmlAttributes, metadataProvider: null);
        }

        [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 labelText, IDictionary<string, object> htmlAttributes)
        {
            return LabelFor(html, expression, labelText, htmlAttributes, metadataProvider: null);
        }

        internal static MvcHtmlString LabelFor<TModel, TValue>(this HtmlHelper<TModel> html, Expression<Func<TModel, TValue>> expression, string labelText, object htmlAttributes, ModelMetadataProvider metadataProvider)
        {
            return LabelFor(html,
                            expression,
                            labelText,
                            HtmlHelper.AnonymousObjectToHtmlAttributes(htmlAttributes),
                            metadataProvider);
        }

        internal static MvcHtmlString LabelFor<TModel, TValue>(this HtmlHelper<TModel> html, Expression<Func<TModel, TValue>> expression, string labelText, IDictionary<string, object> htmlAttributes, ModelMetadataProvider metadataProvider)
        {
            return LabelHelper(html,
                               ModelMetadata.FromLambdaExpression(expression, html.ViewData, metadataProvider),
                               ExpressionHelper.GetExpressionText(expression),
                               labelText,
                               htmlAttributes);
        }

        public static MvcHtmlString LabelForModel(this HtmlHelper html)
        {
            return LabelForModel(html, labelText: null);
        }

        public static MvcHtmlString LabelForModel(this HtmlHelper html, string labelText)
        {
            return LabelHelper(html, html.ViewData.ModelMetadata, String.Empty, labelText);
        }

        public static MvcHtmlString LabelForModel(this HtmlHelper html, object htmlAttributes)
        {
            return LabelHelper(html, html.ViewData.ModelMetadata, String.Empty, labelText: null, htmlAttributes: HtmlHelper.AnonymousObjectToHtmlAttributes(htmlAttributes));
        }

        public static MvcHtmlString LabelForModel(this HtmlHelper html, IDictionary<string, object> htmlAttributes)
        {
            return LabelHelper(html, html.ViewData.ModelMetadata, String.Empty, labelText: null, htmlAttributes: htmlAttributes);
        }

        public static MvcHtmlString LabelForModel(this HtmlHelper html, string labelText, object htmlAttributes)
        {
            return LabelHelper(html, html.ViewData.ModelMetadata, String.Empty, labelText, HtmlHelper.AnonymousObjectToHtmlAttributes(htmlAttributes));
        }

        public static MvcHtmlString LabelForModel(this HtmlHelper html, string labelText, IDictionary<string, object> htmlAttributes)
        {
            return LabelHelper(html, html.ViewData.ModelMetadata, String.Empty, labelText, htmlAttributes);
        }

        internal static MvcHtmlString LabelHelper(HtmlHelper html, ModelMetadata metadata, string htmlFieldName, string labelText = null, IDictionary<string, object> htmlAttributes = null)
        {
            string resolvedLabelText = labelText ?? metadata.DisplayName ?? metadata.PropertyName ?? htmlFieldName.Split('.').Last();
            if (String.IsNullOrEmpty(resolvedLabelText))
            {
                return MvcHtmlString.Empty;
            }

            TagBuilder tag = new TagBuilder("label");
            tag.Attributes.Add("for", TagBuilder.CreateSanitizedId(html.ViewContext.ViewData.TemplateInfo.GetFullHtmlFieldName(htmlFieldName)));
            tag.SetInnerText(resolvedLabelText);
            tag.MergeAttributes(htmlAttributes, replaceExisting: true);
            return tag.ToMvcHtmlString(TagRenderMode.Normal);
        }
    }
}