I am using the eBay trading API to compare my eBay listings against a master database, sending any additions or revisions via the API. When it comes to checking which pictures are listed I am comparing the URLs in the PictureDetails section from GetItem with my original list of self-hosted picture URLs. I have to look in the ExternalPictureURL field to see the originally submitted picture URLs. This is working in general, but I have noticed that in some cases where I have multiple pictures the ExternalPictureURL fields contain just one image URL. The PictureURL fields contain a longer list of images, but of course these are the eBay hosted images and the URLs are different, so cannot be compared with the original source in my database. I have noticed that when this happens PhotoDisplay is set to 'PicturePack'. It may be the case that this is happening for every listing which has more than one picture--I'm not sure. So my question: what is the correct way to check the pictures that eBay knows about for a listing against a list of more than one self hosted picture URL?
What you are doing is correct. Before very recently you could not upload more than 1 self hosted picture. So I would need to see an exact ItemID where you should be getting back multiple pictures but only see one ExternalPictureURL. But from what you explained everything seems correct and seems to be working as expected. It might be when you only get back 1 ExternalPictureURL but see multiple pictures on the listings they pictures were added at the variation level. But again I am just guessing without examples.
For a listing with multiple seller hosted images, our gallery consumer process will first download the first/gallery image (up to 4 retries), when this is successful the consumer will then download images 2 – 12 (no retry). If the download of any of these images (2-12) failed, all of the downloads (2-12) will be abandoned. So for the first item 251768466542, there was a failure with one or more downloads of images 2 – 12. As for the second item 251773770161, all the downloads were successful. Only when all the downloads are successful the PICTURE_URL field will contain converted Zoom image Urls (all Zoom Urls or none; cannot have a mix). Hope that answers your question.
Yes we don't know of any changes made for self hosted images. Also if a change was made and you were to just re upload the exact same URL no change would be made from our end. That is because we assume no change was made and we just skip over the URL that had been used previously. So best practice is to always upload to EPS first, and use those images. And if any changes were made with your images you would want to re-upload them to EPS again and then revise the item with the new URL's. Another route would be if you send the exact same external URL again is to use some sort of cache busting technique to get us to look at the image again.https://