I have a friend who has a WordPress site running WooCommerce, as well as an eBay storefront. He gets a lot more traffic and sales through eBay, but the vast majority of his inventory (~12k items) is on the WordPress site, so he wants to move all his stuff over to eBay.
I've downloaded all the data, so I have all the product information (it's mostly CDs, so Artist, Title, Genre, etc.) and I have all the images. Now I want to create a little app that will help him easily post all this stuff as new items in his storefront, so he doesn't have to post 12k items "by hand" through the regular eBay website.
I tried finding some tutorials or guides, but everything out there I am finding to be extremely confusing. For instance, I found this tutorial about listing an item:
Since I know C#, I tried downloading the .NET SDK and setting something up with that. I managed to do the "hello world" get eBay official time call (not sure that really worked - it just gave me back the current UTC time, what does that prove?). According to that tutorial linked above, the first step to listing an item is figuring out which "category" your item should be. So I hacked around with the .NET code and figured out (I thought) how to do a "GetCategories" call from the sandbox. However, I get zero results (but no errors?).
Looking at the JSON payload for that example, it seems like they're trying to list an Apple Watch. OK. But you know what I don't see in the JSON payload? A CATEGORY NUMBER. So is that first tutorial wrong, do you not actually need a category number? And what about...EVERYTHING ELSE IN THE JSON PAYLOAD? Where is the documentation that tells you the schema of what is required in the JSON to list an item?
My head is spinning because there's all this contradictory information out there, stuff that's supposed to be step one (get categories) does NOT work using one of the SDKs, and appears to not even be a requirement using the REST APIs, and there just seems to be a lot of missing information about how to get things done.
How can I learn how to create a listing? Where do I start?