Question

Dynamically, I would like to take a string property like “GPARank” and change the value of it.

normally, I would have

var rank = gpa.ForEach(x => x.GPARank = i);

But in this case, I don’t know which property I am changing at compile time. I tried to modify Marc Gravell’s code at Dynamic LINQ OrderBy on IEnumerable<T> for my uses, but my brain exploded.

Thanks!

Figured out using reflection, still want a dynamic linq expressions solution

gpa.ForEach(x => x.GetType().GetProperty(_ColumnRank).SetValue(x, i += 1 , null));

I was able to figure out how to do this using reflection. But if anyone has the time or desire to show me how to do this using dynamic linq with run-time expressions, I would really like to know how to do this.

Answer 1

Pseudo-code, untested:

string propName = "GPARank";  
PropertyInfo prop = typeof(Item).GetProperty(propName);
Action<Item,string> setter = (Action<Item,string>)Delegate.CreateDelegate(
    typeof(Action<Item,string>), prop.GetSetMethod());
foreach(Item obj in list) setter(obj,newValue);

To be honest though, in most cases just using the PropertyInfo directly (via SetValue) will work; the only change I would make to your original code in that case would be to move obtaining the PropertyInfo outside the loop, rather than per-item.