[英]Custom MVC HtmlHelper that uses existing HtmlHelpers with Expressions
我正在嘗試制作一個自定義的HtmlHelper,它將在現有HtmlHelper(例如Html.TextBoxFor
和Html.LabelFor
的幫助下生成多個HTML元素。 我遇到的主要問題是,除非將它們全部傳遞到我的自定義HtmlHelper中,否則我將無法創建供這些現有幫助器使用的表達式。 我希望能夠將整個模型傳遞給自定義的HtmlHelper並在幫助器內部創建Expressions並將它們傳遞給現有的。 我正在嘗試以這種方式進行操作,以希望這些屬性仍然可以使用,例如DisplayName的Required和國際化。 這可能嗎?
我知道我可以通過將每個Address屬性通過表達式傳遞到自定義HtmlHelper中來做到這一點,但是它並不像在助手中完成那樣干凈和易於使用。
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; }
}
自定義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)
您可以使用反射和表達式樹來完成此操作,如下所示:
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,這假定TModel是您的Address對象,因此您也不必傳遞它。HTML幫助器中的TModel來自強類型視圖,因此,如果您擁有@model類型為Address的視圖,則可以使用上述方法
該視圖將像這樣使用它:
@model Address
@Html.AddressEditorForModel("prefix", true)
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