Identifying StatTrak Items by classid/instanceid

[kryo]

I noticed that StatTrak items change classid and instanceid after a trade. Given a trade that has two StatTrak items with the same market_hash_name I'm not sure if it's possible to link the before and after items. Any ideas?

[Dr. McKay]

Using classid/instanceid to track a specific item doesn't work anyway.

[cookie]

Using classid/instanceid to track a specific item doesn't work anyway.

 

[Dr. McKay]

To be more specific (and I should really make some kind of wiki with this information), classid and instanceid are used to identify a description, not an item. A description is the item's display information. Two identical items will most likely have identical classid/instanceid; this means that using classid and instanceid to track a specific unique item really won't work.

 

It would be like trying to use a car's make, model, and color to track that unique car. Sure you'll get close, but you won't always find that exact car. You want its license plate or VIN for that (assetid).

[kryo]

Right but when handling a trade we have two assetids for each item, sent item and received item. If I want to get the inspect in-game link for the received item I need to somehow match it with the sent item.

[Dr. McKay]

You can't track a specific item across a trade. You can get the IDs of the new items you received in a trade from the trade receipt page (steam-tradeoffer-manager has a method for this), but there is no defined order of items in the receipt. You can match inputs to outputs using their market_name and other defining characteristics, but if you have two identical items in a trade, there's no way to know for sure which specific item is which.

[kryo]

Yeah I am using the classid/instanceid and the market_name as a last resort, meanwhile ensuring that I don't count the same item twice. I was hoping that there would be another way but thanks for the confirmation.