Thanks, But I need more data than this: I want to identify listing that originally had more than 1 quantity. Meaning, multi quantity listings. doesn't matter if now there is only 1 item left. How can I do that? Also, Min Quantity is a filter, but how do I know for each listing how many items are actually available and how many left? how to get this data in the XML response?
The Finding API has more of a database overview (or theoretical) slant than a practical one and is limited on useful details like this. You have to chain out to the Shopping API using the item numbers for the details. I don't know any way to get this in a single call or sequence. Shopping GetMultipleItems returns Quantity (listed) and QuantitySold. You can batch item numbers and check 20 items at a time with this call to limit the call count. You could approach it iteratively. This is easier if your scope is limited i.e. you aren't trying to monitor all of eBay, but just selected categories or certain products. Scan for the multiple qty items periodically and record the item numbers in a database, then use that list with the Shopping API to update the quantities and check active status of the listings. Drop items that have ended as needed. This way you discover the items while they have multiple qty and can still access them when drop to qty=1 and Finding can't see them anymore. You still might miss a few in between checks if they list and sell rapidly. You'd have to decide whether it's worth the effort or not to track this data and make extra API calls to get it. These sort of trade-offs are common with Finding API.