c# mvc helper extension Html.DisplayFor
Hours later. Interneting later. Hair pulling later.
Prs_Role_ID_Deleted is an int .
In my Details.cshtml, I am trying to have it output a "" (empty string) if the value of model.Prs_Role_ID_Deleted = 0 (zeri).
The problem is I am unable unable to get the value of model => model.Prs_Role_ID_Deleted . I can get the property name. I can get the model.Prs_Role_ID_Deleted .
I am unable to get the value of model.Prs_Role_ID_Deleted which should equal 22.
@Html.ZZZ(model => model.Prs_Role_ID_Deleted)
public static MvcHtmlString ZZZ<TModel, TValue>(this HtmlHelper<TModel> helper, Expression<Func<TModel, TValue>> expression)
{
var id = helper.ViewContext.ViewData.TemplateInfo.GetFullHtmlFieldId(ExpressionHelper.GetExpressionText(expression));
return "whatever";
}
I am beginning to think it is not possible to ascertain the value.
Thanks SLaks. That was the solution.
Posting solution for other developers.
AFTER SLaks advice @Html.DisplayForWithID_ZeroIsBlank(model => model.Prs_Role_ID_Deleted, "span")
public static MvcHtmlString DisplayForWithID_ZeroIsBlank(this HtmlHelper helper, Expression> expression, string wrapperTag = "span") { var id = helper.ViewContext.ViewData.TemplateInfo.GetFullHtmlFieldId(ExpressionHelper.GetExpressionText(expression)); TModel model = (TModel)helper.ViewContext.ViewData.ModelMetadata.Model; var ctlValue = expression.Compile()(helper.ViewData.Model); string OutputValue = "Silly developer. This only works for int."; Type type = ctlValue.GetType(); if (type.Equals(typeof(int))) { string s = ctlValue.ToString().Trim(); if (ctlValue == null || ctlValue.ToString().Trim() == "0") { OutputValue = ""; } else { OutputValue = ctlValue.ToString(); } } return MvcHtmlString.Create(string.Format("<{0} id="{1}">{2}", wrapperTag, id, OutputValue, helper.DisplayFor(expression))); }
您需要将表达式编译为委托，然后在模型上调用它：
expression.Compile()(helper.ViewData.Model);