从属性名称获取属性lambda（其中属性类型可以为空）(get property lambda from property Name (Where property type can be nullable))

 您好，我基本上需要一个具有以下签名的功能 
 
Expression<Func<T, object>> GetPropertyLambda(string propertyName)
 
 我已经做了几次尝试，但是当房产可空时，问题就出现了 
 它是这样的 
 
ParameterExpression param = Expression.Parameter(typeof(T), "arg");

Expression member = Expression.Property(param, propertyName);

//this next section does conver if the type is wrong however
// when we get to Expression.Lambda it throws
Type typeIfNullable = Nullable.GetUnderlyingType(member.Type);
if (typeIfNullable != null)
{
    member = Expression.Convert(member, typeIfNullable);
}                       
return Expression.Lambda<Func<T, object>>(member, param);
 
 例外是 
 
 
 
 'System.Decimal'类型的表达式不能用于返回类型'System.Object' 
 
 
 我真的会想出一些想法，也为什么这不会按预期工作 
 
 谢谢 

Hi there I basically need a function with the following signature
 
Expression<Func<T, object>> GetPropertyLambda(string propertyName)
 
I have made a few attempts but the problem arise when the property is nullable
 it goes something like this 
 
ParameterExpression param = Expression.Parameter(typeof(T), "arg");

Expression member = Expression.Property(param, propertyName);

//this next section does conver if the type is wrong however
// when we get to Expression.Lambda it throws
Type typeIfNullable = Nullable.GetUnderlyingType(member.Type);
if (typeIfNullable != null)
{
    member = Expression.Convert(member, typeIfNullable);
}                       
return Expression.Lambda<Func<T, object>>(member, param);
 
The Exception is 
 
 
 
Expression of type 'System.Decimal' cannot be used for return type 'System.Object'
 
 
I would really apreciate some ideas and also why this doesnt work as expected
 
Thanks

原文：https://stackoverflow.com/questions/1803142