Get name of property as a string

Question

(See below solution I created using the answer I accepted)

I'm trying to improve the maintainability of some code involving reflection. The app has a .NET Remoting interface exposing (among other things) a method called Execute for accessing parts of the app not included in its published remote interface.

Here is how the app designates properties (a static one in this example) which are meant to be accessible via Execute:

RemoteMgr.ExposeProperty("SomeSecret", typeof(SomeClass), "SomeProperty");

So a remote user could call:

string response = remoteObject.Execute("SomeSecret");

and the app would use reflection to find SomeClass.SomeProperty and return its value as a string.

Unfortunately, if someone renames SomeProperty and forgets to change the 3rd parm of ExposeProperty(), it breaks this mechanism.

I need to the equivalent of:

SomeClass.SomeProperty.GetTheNameOfThisPropertyAsAString()

to use as the 3rd parm in ExposeProperty so refactoring tools would take care of renames.

Is there a way to do this? Thanks in advance.

Okay, here's what I ended up creating (based upon the answer I selected and the question he referenced):

// <summary>
// Get the name of a static or instance property from a property access lambda.
// </summary>
// <typeparam name="T">Type of the property</typeparam>
// <param name="propertyLambda">lambda expression of the form: '() => Class.Property' or '() => object.Property'</param>
// <returns>The name of the property</returns>
public string GetPropertyName<T>(Expression<Func<T>> propertyLambda)
{
    var me = propertyLambda.Body as MemberExpression;

    if (me == null)
    {
        throw new ArgumentException("You must pass a lambda of the form: '() => Class.Property' or '() => object.Property'");
    }

    return me.Member.Name;
 }

Usage:

// Static Property
string name = GetPropertyName(() => SomeClass.SomeProperty);

// Instance Property
string name = GetPropertyName(() => someObject.SomeProperty);

Now with this cool capability, it's time to simplify the ExposeProperty method. Polishing doorknobs is dangerous work...

Thanks everyone.

Answer 1

You can use Reflection to obtain the actual names of the properties.

http://www.csharp-examples.net/reflection-property-names/

If you need a way to assign a "String Name" to a property, why don't you write an attribute that you can reflect over to get the string name?

[StringName("MyStringName")]
private string MyProperty
{
    get { ... }
}

Answer 2

You can use the StackTrace class to get the name of the current function, (or if you put the code in a function, then step down a level and get the calling function).

See http://msdn.microsoft.com/en-us/library/system.diagnostics.stacktrace(VS.71).aspx

Answer 3

There's a well-known hack to extract it from lambda expression (this is from the PropertyObserver class, by Josh Smith, in his MVVM foundation):

    private static string GetPropertyName
        (Expression<Func<TPropertySource, object>> expression)
    {
        var lambda = expression as LambdaExpression;
        MemberExpression memberExpression;
        if (lambda.Body is UnaryExpression)
        {
            var unaryExpression = lambda.Body as UnaryExpression;
            memberExpression = unaryExpression.Operand as MemberExpression;
        }
        else
        {
            memberExpression = lambda.Body as MemberExpression;
        }

        Debug.Assert(memberExpression != null, 
           "Please provide a lambda expression like 'n => n.PropertyName'");

        if (memberExpression != null)
        {
            var propertyInfo = memberExpression.Member as PropertyInfo;

            return propertyInfo.Name;
        }

        return null;
    }

---

Sorry, this was missing some context. This was part of a larger class where TPropertySource is the class containing the property. You could make the function generic in TPropertySource to extract it from the class. I recommend taking a look at the full code from the MVVM Foundation.

Answer 4

The PropertyInfo class should help you achieve this, if I understand correctly.

1. Type.GetProperties() method

   PropertyInfo[] propInfos = typeof(ReflectedType).GetProperties();
   propInfos.ToList().ForEach(p => 
       Console.WriteLine(string.Format("Property name: {0}", p.Name));
   

Is this what you need?

Answer 5

Using GetMemberInfo from here: http://stackoverflow.com/questions/671968/retrieving-property-name-from-lambda-expression you can do something like this:

RemoteMgr.ExposeProperty(() => SomeClass.SomeProperty)

public class SomeClass
{
    public static string SomeProperty
    {
        get { return "Foo"; }
    }
}

public class RemoteMgr
{
    public static void ExposeProperty<T>(Expression<Func<T>> property)
    {
        var expression = GetMemberInfo(property);
        string path = string.Concat(expression.Member.DeclaringType.FullName,
            ".", expression.Member.Name);
        // Do ExposeProperty work here...
    }
}

public class Program
{
    public static void Main()
    {
        RemoteMgr.ExposeProperty("SomeSecret", () => SomeClass.SomeProperty);
    }
}