Question

我正在研究一个VB。 NET项目正在使用ASP。 NET MVC 2. 结论我利用我模型中元数据添加验证和其他属性的能力。

例如,我增加了以下特性:<DisplayName(“未来名称”)>对我模型中的财产作了说明,并且正在使用将这些特性加起来。 Html.LabelFor ( extension methods.

我也添加了<代码><Description (" this is a presentation of the field >>属该模型中的各种特性,并希望以类似方式说明这些特性。

我的问题是——是否存在一种延伸方法,对我来说是这样吗?

如果有的话,有人会引导我正确撰写我自己的文件? I ve以现有方法的签署方法为依据......

<ExtensionAttribute()> _
Public Function HintFor(Of TModel, TProperty) _
                       (ByVal htmlHelper As HtmlHelper(Of TModel), _
                        ByVal expression As Expression(Of Func(Of TModel, TProperty))) As MvcHtmlString

End Function

但我必须承认这部分内容远远超出了我的Lambda /LINQ /? 现阶段的知识!

预告......

Answer 1

如果你重新使用MVC 3,你可以使用<代码>DisplayAttribute,并且仅使用描述参数。

Public Class User
    <Display(Name = "User name", Description = "This is a description")> _
    Public Property Name As String
End Class


<System.Runtime.CompilerServices.Extension> _
Public Shared Function HintFor(Of TModel, TValue)(html As HtmlHelper(Of TModel), expression As Expression(Of Func(Of TModel, TValue))) As IHtmlString
    Dim attribute = ModelMetadata.FromLambdaExpression(Of TModel, TValue)(expression, html.ViewData)

    Return MvcHtmlString.Create(attribute.Description)
End Function

Mvc2

我只是经过了一个奇怪的考验,看看看这一工程是否可行。 (我不经常使用VB并使用在线转换器) 没有任何错误或任何错误,但会产生预期的结果。

<System.Runtime.CompilerServices.Extension()> _
Public Shared Function HintFor(Of TModel, TValue)(html As HtmlHelper(Of TModel),     expression As Expression(Of Func(Of TModel, TValue))) As IHtmlString

    Dim ex As MemberExpression = DirectCast(expression.Body, MemberExpression)
    For Each attribute As Attribute In ex.Expression.Type.GetProperty(ex.Member.Name).GetCustomAttributes(True)
        If GetType(System.ComponentModel.DescriptionAttribute) = attribute.[GetType]() Then
            Return MvcHtmlString.Create(DirectCast(attribute, System.ComponentModel.DescriptionAttribute).Description)
        End If
    Next

    Dim x = ModelMetadata.FromLambdaExpression(Of TModel, TValue)(expression, html.ViewData)
    Return MvcHtmlString.Create(x.Description)
End Function

Additional

我确实不敢肯定,为什么在你能够这样做的时候,我就这样做了。 (尽管我称“MVC 2”可能无法与数据发布妥善合作)

<System.Runtime.CompilerServices.Extension()> _
Public Shared Function HintFor(Of TModel, TValue)(html As HtmlHelper(Of TModel),     expression As Expression(Of Func(Of TModel, TValue))) As IHtmlString
    Dim x = ModelMetadata.FromLambdaExpression(Of TModel, TValue)(expression, html.ViewData)
    Return MvcHtmlString.Create(x.Description)
End Function

Answer 2

此处为C#的更完整的版本I,也支持htmlAttribut:

public static MvcHtmlString DescriptionFor<TModel, TValue>(this HtmlHelper<TModel> htmlHelper, Expression<Func<TModel, TValue>> expression, object htmlAttributes)
{
    var metadata = ModelMetadata.FromLambdaExpression(expression, htmlHelper.ViewData);
    var description = metadata.Description;

    RouteValueDictionary anonymousObjectToHtmlAttributes = HtmlHelper.AnonymousObjectToHtmlAttributes(htmlAttributes);

    TagBuilder tagBuilder = new TagBuilder("span");
    tagBuilder.MergeAttributes<string, object>(anonymousObjectToHtmlAttributes);
    tagBuilder.SetInnerText(description);

    return new MvcHtmlString(tagBuilder.ToString(TagRenderMode.Normal));
}

与此类似:

[Display(Name = "Style", Description = "Some description of this field")]
public float Style { get; set; }

@Html.DescriptionFor(model => model.Style, new { @class = "help-inline" })

Mvc2

Additional

友情链接