Question

我正在尝试制作一个自定义HtmlHelper，它将在Html.TextBoxFor和Html.LabelFor等现有HtmlHelper的帮助下生成多个HTML元素。我遇到的主要问题是我无法创建表达式以供这些现有帮助程序使用，除非它们都单独传递到我的自定义HtmlHelper中。我希望能够将整个模型传递给自定义HtmlHelper并在帮助程序内部创建表达式并将它们传递给现有模型。我试图这样做，希望属性仍然有效，例如DisplayName的Required和国际化。这可能吗？

我知道我可以通过将每个Address属性传递到自定义HtmlHelper表达式来实现它，但它并不像在帮助程序中完成它那样干净且易于使用。

地址模型

public class Address
{
    [Required(ErrorMessage = "Required"), DisplayName("First Name")]
    public String FirstName { get; set; }

    [Required(ErrorMessage = "Required"), DisplayName("Last Name")]
    public String LastName { get; set; }

    [Required(ErrorMessage = "Required"), DisplayName("Line 1")]
    public String Line1 { get; set; }

    [Required(ErrorMessage = "Required"), DisplayName("Line 2")]
    public String Line2 { get; set; }

    [Required(ErrorMessage = "Required"), DisplayName("City")]
    public String City { get; set; }

    [Required(ErrorMessage = "Required"), DisplayName("State")]
    public String State { get; set; }

    [Required(ErrorMessage = "Required"), DisplayName("Country")]
    public String Country { get; set; }

    [Required(ErrorMessage = "Required"), DisplayName("Postal Code")]
    public String PostalCode { get; set; }
}

自定义HtmlHelper

public static class AddressExtension
{
    public static MvcHtmlString AddressEditorForModel<TModel>(this HtmlHelper<TModel> helper, Address address, String prefix, Boolean showLabels)
    {          
        // There will be more markup in here, this is just slimmed down..

        StringBuilder sb = new StringBuilder();
        sb.AppendLine(String.Format("<div id='{0}_AddressContainer' >", prefix));

        // First Name
        if (showLabels)
            sb.AppendLine(helper.DisplayFor(????).ToString());            
        sb.AppendLine(helper.EditorFor(????).ToString());

        // Last Name
        if (showLabels)
            sb.AppendLine(helper.DisplayFor(????).ToString());            
        sb.AppendLine(helper.EditorFor(????).ToString());

        // Line 1
        if (showLabels)
            sb.AppendLine(helper.DisplayFor(????).ToString());            
        sb.AppendLine(helper.EditorFor(????).ToString());

        // Line 2
        if (showLabels)
            sb.AppendLine(helper.DisplayFor(????).ToString());            
        sb.AppendLine(helper.EditorFor(????).ToString());

        // City
        if (showLabels)
            sb.AppendLine(helper.DisplayFor(????).ToString());            
        sb.AppendLine(helper.EditorFor(????).ToString());

        // State
        if (showLabels)
            sb.AppendLine(helper.DisplayFor(????).ToString());            
        sb.AppendLine(helper.EditorFor(????).ToString());

        // Country
        if (showLabels)
            sb.AppendLine(helper.DisplayFor(????).ToString());            
        sb.AppendLine(helper.EditorFor(????).ToString());

        // Postal Code
        if (showLabels)
            sb.AppendLine(helper.DisplayFor(????).ToString());            
        sb.AppendLine(helper.EditorFor(????).ToString());

        sb.AppendLine("</div>");

        return MvcHtmlString.Create(sb.ToString());
    }

查看（cshtml）

@Html.AddressEditorForModel(Model, "test", true)

Answer 1

您可以使用这样的反射和表达式树来执行此操作：

public static MvcHtmlString AddressEditorForModel<TModel>(this HtmlHelper<TModel> helper, string prefix, bool showLabels)
{          
    // There will be more markup in here, this is just slimmed down..

    StringBuilder sb = new StringBuilder();
    sb.AppendLine(String.Format("<div id='{0}_AddressContainer' >", prefix));

         //Create a parameter expression for the model type
         ParameterExpression paramExpr = Expression.Parameter(typeof (TModel));
         //Loop through the properties you want to create a DisplayFor for
         foreach (var property in typeof (TModel).GetProperties())
         {
             //Create a member access expression for accessing this property
             MemberExpression propertyAccess = Expression.MakeMemberAccess(paramExpr, property);
             //Create the lambda expression (eg. "x => x.Name")
             var lambdaExpr = Expression.Lambda<Func<TModel, string>>(propertyAccess, paramExpr);
             //Pass this lambda to the DisplayFor method
             sb.AppendLine(helper.DisplayFor(lambdaExpr).ToString());

         }

...rest of your method

但是，假设 TModel 是您的地址对象，因此您也不需要将其传入。 TModel 在HTML帮助器中来自强类型视图，因此如果你有一个@model类型是地址的视图，那么你可以使用上面的方法

视图会像这样使用它：

@model Address

@Html.AddressEditorForModel("prefix", true)

自定义MVC HtmlHelper使用现有的带有表达式的HtmlHelper

1 个答案: