How can I pass a property as a delegate?

Question

This is a theoretical question, I\'ve already got a solution to my problem that took me down a different path, but I think the question is still potentially interesting.

Answer 1

I like using expression trees to solve this problem. Whenever you have a method where you want to take a "property delegate", use the parameter type Expression>. For example:

public void SetPropertyFromDbValue(
    T obj,
    Expression> expression,
    TProperty value
)
{
    MemberExpression member = (MemberExpression)expression.Body;
    PropertyInfo property = (PropertyInfo)member.Member;
    property.SetValue(obj, value, null);
}

Nice thing about this is that the syntax looks the same for gets as well.

public TProperty GetPropertyFromDbValue(
    T obj,
    Expression> expression
)
{
    MemberExpression member = (MemberExpression)expression.Body;
    PropertyInfo property = (PropertyInfo)member.Member;
    return (TProperty)property.GetValue(obj, null);
}

Or, if you're feeling lazy:

public TProperty GetPropertyFromDbValue(
    T obj,
    Expression> expression
)
{
    return expression.Compile()(obj);
}

Invocation would look like:

SetPropertyFromDbValue(myClass, o => o.Property1, reader["field1"]);
GetPropertyFromDbValue(myClass, o => o.Property1);