.NET MVC 强类型助手 - 从属性中获取价值？
我正在创建一个强类型助手（参考：所以问题）。正如下面代码中的“注释”，是否可以以某种方式从表达的属性中获取值，从而绕过可选的 selectedValue 参数？
<Extension()> _
Public Function DatePickerFor(Of TModel As Class, TProperty)(ByVal htmlHelper As HtmlHelper(Of TModel), ByVal expression As Expression(Of Func(Of TModel, TProperty)), Optional ByVal selectedValue As Nullable(Of Date) = Nothing) As MvcHtmlString
Dim inputName = ExpressionHelper.GetExpressionText(expression)
Dim inputValue = selectedValue
//Something like this possible?
//inputValue = ExpressionHelper.GetExpressionValue(expression)
Return DatePicker(htmlHelper, inputName, inputValue)
End Function
I'm creating a strongly typed helper (ref: SO question). As 'commented' in the code below, is it possible to somehow get the value from the expressed property and thus bypass the optional selectedValue parameter?
<Extension()> _
Public Function DatePickerFor(Of TModel As Class, TProperty)(ByVal htmlHelper As HtmlHelper(Of TModel), ByVal expression As Expression(Of Func(Of TModel, TProperty)), Optional ByVal selectedValue As Nullable(Of Date) = Nothing) As MvcHtmlString
Dim inputName = ExpressionHelper.GetExpressionText(expression)
Dim inputValue = selectedValue
//Something like this possible?
//inputValue = ExpressionHelper.GetExpressionValue(expression)
Return DatePicker(htmlHelper, inputName, inputValue)
End Function
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如果您想获取表达式指向的相应属性的值，可以使用 FromLambdaExpression 方法：
If you want to get the value of the corresponding property that the expression is pointing to you could use the FromLambdaExpression method: