Is there a direct API that can give me the CatalogNode/CatalogNodes that product or variant belongs to? Just by passing the entry code or (sku)?
I *think* you'll want to take a look at the EPiServer.Commerce.Catalog.Linking namespace (http://world.episerver.com/documentation/Class-library/?documentId=commerce/8/551C57ED). There is a class called NodeRelation that may be what you're looking for. Here's is documentation surrounding it: http://world.episerver.com/documentation/Items/Developers-Guide/EPiServer-Commerce/8/Content/Categorizations/
There is no direct API:s to do that. You'll have to do it in two steps:
- First use ReferenceConverter to get the contentlink from the Code
- Secondly use ILinksRepository/IRelationRepository to get the NodeRelation for that content link - refer to Richley's post for more information.