I'm using the Advertising API to get reports and retrieving the entities for Sponsored Brands and Sponsored Products. I need to get all the entities. The "How to use the Amazon Advertising API" manual says that
"Asynchronous snapshots vs synchronous batch GETs for campaign management
The API is used for synchronous batch operations to get campaigns, ad groups, keywords, and ads. Additionally, the API provides an asynchronous interface for getting a complete snapshot of all entities of a single type. Snapshots are generally more efficient if the client intends to get all campaigns, ad groups, keywords, or ads in bulk. This is useful for clients who replicate their account structures locally."
So I'm using the entity snapshots endpoints (https://advertising.amazon.com/API/docs/en-us/reference/sponsored-products/2/snapshots; the links provided here and below are for the Sponsored Products as example; same requests are done by the Sponsored Brands entity snapshots endpoint, although I can retrieve only a few entities via it).
If I used individual endpoints, I would call the listEntity or the listEntityEx endpoints where entity can be campaigns, adGroups, keywords etc. As says the documentation for each entity, the listEntityEx "retrieves a list of entities with extended fields". You can see the example for the campaigns here -- https://advertising.amazon.com/API/docs/en-us/reference/sponsored-products/2/campaigns, see listCampaign (GET /v2/sp/campaigns) and listCampaignEx (GET /v2/sp/campaigns/extended) chapters.
In case of the campaigns listCampaignEx returns 4 additional fields -- createdDate, lastUpdatedDate, servingStatus and placement. First 3 of them are part of each extended list response.
The problem is that the entity snapshots (POST /v2/sp/entity/snapshot) endpoint returns in fact only the "simple" response, without the "extended" fields. It is disappointing because to retrieve these fields I need to make a heavier request to API, and do more requests because the response is paginated. So the suggestion to use snapshots because of their efficiency is senseless: if I need to bulk retrieve all entities then usually I want to get the whole information at once without making the additional numerous requests.
Finally, the question is if it's possible to retrieve the extended fields using the entity snapshots endpoint, and how to do it if it's possible? Maybe it can be done by passing an additional parameter in the POST body to the API?