How can I get the name and value of a property using reflection?

Question

I have this code and I am using it to raise the PropertyChanged event without passing the name of property to the function.

private void RaisePropertyChanged<TValue>(Expression<Func<TValue>> propertySelector)
    {
        var memberExpression = propertySelector.Body as MemberExpression;
        if (memberExpression != null)
        {
            if (this.PropertyChanged != null)
            {
                this.PropertyChanged(this, new PropertyChangedEventArgs(memberExpression.Member.Name));
            }
        }
    }

and I am calling it in this way:

  this.RaisePropertyChanged(() => this.IsReady);

Which will raise the PropertyChanged event for the IsReady property. I like the idea as writing code in this way will help to change the name of the property very easily.

Now I want to use the same technique to pass the name and value of a property to a method. Is there any way that I can do this?

Do you want to pass a property of the calling class, or some other class? — Kristoffer Lindvall
– Kristoffer Lindvall, Commented Nov 2, 2011 at 12:00
possible duplicate of Using an expression tree to read the name and value of a property. Is there an alternative? — nawfal
– nawfal, Commented Apr 27, 2013 at 15:47

Marc Gravell · Accepted Answer · 2011-11-02 12:04:31Z

4

You already have it:

string name = memberExpression.Member.Name;
TValue value = propertySelector.Compile()();

An alternative would be to look at the member.MemberType, cast to PropertyInfo or FieldInfo respectively:

var member = memberExpression.Member;
string name = member.Name;
object value;
switch(member.MemberType) {
    case MemberTypes.Field:
       value = ((FieldInfo)member).GetValue(this);
       break;
    case MemberTypes.Property:
       value = ((PropertyInfo)member).GetValue(this, null);
       break;
    default:
       throw new NotSupportedException(member.MemberType.ToString());
}

However, a simpler approach is... to simply pass the name and value to the method:

Foo("IsReady", IsReady);

It depends a bit on how efficient it needs to be, though (reflection/expression does add an overhead - whether that is significant depends on the context).

edited Nov 2, 2011 at 12:04

answered Nov 2, 2011 at 11:59

Marc Gravell

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Comments

Yahia · Accepted Answer · 2011-11-05 06:27:08Z

0

For getting the name you can use memberExpression.Member.Name and for getting the value you could use this.GetType().GetProperty (memberExpression.Member.Name).GetGetMethod().Invoke (this, null).

edited Nov 5, 2011 at 6:27

answered Nov 2, 2011 at 12:01

Yahia

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