从表达式获取字符串属性名称

我正在尝试写一个强类型的帮助器，它是这样的：

Html.Lookup(x => x.FooId); 

现在我有这个：

 public static MvcHtmlString Lookup(this HtmlHelper html, Func expression) { // get string "FooId" here } 

谁知道怎么弄这个？

Answer 1

 public static class ExpressionsExtractor { public static string Lookup(this HtmlHelper html, Expression> expression) { var memberExpression = expression.Body as MemberExpression; if (memberExpression == null) return null; return memberExpression.Member.Name; } } 

然后你会用它来调用它：

 var propName = Html.Lookup(x => x.FooId); 

Answer 2

又一个代码。

 public MvcHtmlString Lookup(this HtmlHelper html, Expression> expression) { return MvcHtmlString.Create(ExpressionHelper.GetExpressionText(expression)); } 

使用ExpressionHelper类。 Func是委托，Expression在编译时生成ExpressionTree。 Expression.Compile（）返回委托，但Func在运行时不会获得ExpressionTree。

Answer 3

当我在Web项目之外需要此function时，目前使用此类，其中System.Web.Mvc引用不应存在：

 namespace Interreg.Domain{ using System; using System.Linq.Expressions; public class PropertyName{ public static string For( Expression> expression){ var body=expression.Body; return GetMemberName(body); } public static string For( Expression> expression){ var body=expression.Body; return GetMemberName(body); } public static string GetMemberName( Expression expression){ if(expression is MemberExpression){ var memberExpression=(MemberExpression)expression; if(memberExpression.Expression.NodeType== ExpressionType.MemberAccess) return GetMemberName(memberExpression.Expression)+"."+memberExpression.Member.Name; return memberExpression.Member.Name; } if(expression is UnaryExpression){ var unaryExpression=(UnaryExpression)expression; if(unaryExpression.NodeType!=ExpressionType.Convert) throw new Exception(string.Format("Cannot interpret member from {0}",expression)); return GetMemberName(unaryExpression.Operand); } throw new Exception(string.Format("Could not determine member from {0}",expression)); } } } 

关于这个问题的好处是 – 当深度超过一个级别时，它不会丢失点数。

Answer 4

有点晚了，但我发布了一个简单的解决方案，它在.Net 4中为我工作。它在第4行处理值类型

 public PropertyInfo GetPropertyInfo(Expression> propertyLambda) { var member = propertyLambda.Body as MemberExpression; if (member == null) {// value types return Convert(x.property) which can't be cast to MemberExpression var expression = propertyLambda.Body as UnaryExpression; member = expression.Operand as MemberExpression; } return member.Member as PropertyInfo; }