Question

I have the classes:

    [DataContract]
    public class MediaItem : Video
    {
        //used to protect calling api from the incorrectly named video
    }

    [DataContract]
    public class SecureMediaItem : MediaItem
    {
        [DataMember]
        public PlayerEmbedToken Token;
    }

Then I have the following code:

List<MediaItem> dummyItems = new List<MediaItem>();

 //cast the media item into a secure media item
SecureMediaItem retItem = (SecureMediaItem)dummyItems[mediaId];

//TODO: put in the Admin ID
retItem.Token.UserId = 1;
retItem.Token.IpAddress = VLSCore2.VlsSecurity.ParseIpFromString(ipAddress);
retItem.Token.UniquePlayerRef = Guid.NewGuid().ToString();


return retItem;

However Im getting an error:

Unable to cast object of type
‘VLSCore2.Entities.Security.Api.MediaItem’ to type
‘VLSCore2.Entities.Security.Api.SecureMediaItem’.

This is just simply a widending cast is it not? Something stopping it like the DataContract attribute?

Answer 1

No. It’s the opposite of a widening cast. SecureMediaItem is more specific than MediaItem. You could cast a SecureMediaItem to a MediaItem, because a SecureMediaItem is a MediaItem. The other way around isn’t working, because a MediaItem isn’t necessarily a SecureMediaItem.