Identifying a custom indexer using reflection in C#

Question

I have a class with a custom indexer like so

public string this[VehicleProperty property]
{
  // Code
}

How can I identify the custom index

Answer 1

If there is only one indexer, you can use this:

var indexer = typeof(MyClass).GetProperties().First(x => x.GetIndexParameters().Length > 0));

If there are multiple indexers, you can select the overload you want by supplying the arguments like this:

var args = new[] { typeof(int) };
var indexer = typeof(MyClass).GetProperties().First(x => x.GetIndexParameters().Select(y => y.ParameterType).SequenceEqual(args));

You can create a helper extension like this:

//Usage      
var indexer = typeof(MyClass).GetIndexer(typeof(VehicleProperty));
//Class
public static class TypeExtensions
{
  public static PropertyInfo GetIndexer(this Type type, params Type[] arguments) => type.GetProperties().First(x => x.GetIndexParameters().Select(y => y.ParameterType).SequenceEqual(arguments));
}