C# Constraints on Type Parameters what to use for bool

Question

public static MvcHtmlString CheckBoxListFor<TModel, TValue>(this HtmlHelper<TModel> html, Expression<Func<TModel, TValue>> expression) where TValue : bool

and bool is not valid. Boolean is also not valid. What can I use? TValue must be bool ?

edit: I am writing HTMLHELPER for mvc3 and later onis used as html.CheckBoxFor(expression) so TValue must be generic

Answer 1

如果TValue必须为bool ，则它不是通用的。

public static MvcHtmlString CheckBoxListFor<TModel>(this HtmlHelper<TModel> html, Expression<Func<TModel, bool>> expression)

Answer 2

然后只需删除TValue类型参数，并将其替换为bool ：

public static MvcHtmlString CheckBoxListFor<TModel>(this HtmlHelper<TModel> html, Expression<Func<TModel, bool>> expression)

Answer 3

From your comments, it looks to me like you need two different overloads:

public static MvcHtmlString CheckBoxListFor<TModel>(this HtmlHelper<TModel> html,
    Expression<Func<TModel, bool>> predicateExpression)

and

public static MvcHtmlString CheckBoxListFor<TModel, TValue>(this HtmlHelper<TModel> html,
    Expression<Func<TModel, TValue>> expression)

Internally, you can share the inner implementation and add what you need.