Retrieving Property name from lambda expression

Question

Is there a better way to get the Property name when passed in via a lambda expression? Here is what i currently have.

eg.

GetSortingInfo         


        

Answer 1

Here's an update to method proposed by Cameron. The first parameter is not required.

public PropertyInfo GetPropertyInfo(
    Expression> propertyLambda)
{
    Type type = typeof(TSource);

    MemberExpression member = propertyLambda.Body as MemberExpression;
    if (member == null)
        throw new ArgumentException(string.Format(
            "Expression '{0}' refers to a method, not a property.",
            propertyLambda.ToString()));

    PropertyInfo propInfo = member.Member as PropertyInfo;
    if (propInfo == null)
        throw new ArgumentException(string.Format(
            "Expression '{0}' refers to a field, not a property.",
            propertyLambda.ToString()));

    if (type != propInfo.ReflectedType &&
        !type.IsSubclassOf(propInfo.ReflectedType))
        throw new ArgumentException(string.Format(
            "Expresion '{0}' refers to a property that is not from type {1}.",
            propertyLambda.ToString(),
            type));

    return propInfo;
}

You can do the following:

var propertyInfo = GetPropertyInfo(u => u.UserID);
var propertyInfo = GetPropertyInfo((SomeType u) => u.UserID);

Extension methods:

public static PropertyInfo GetPropertyInfo(this TSource source,
    Expression> propertyLambda) where TSource : class
{
    return GetPropertyInfo(propertyLambda);
}

public static string NameOfProperty(this TSource source,
    Expression> propertyLambda) where TSource : class
{
    PropertyInfo prodInfo = GetPropertyInfo(propertyLambda);
    return prodInfo.Name;
}

You can:

SomeType someInstance = null;
string propName = someInstance.NameOfProperty(i => i.Length);
PropertyInfo propInfo = someInstance.GetPropertyInfo(i => i.Length);