Data Sources on Service: "Web.MultiPartPost" vs "Web.Contents" Data Sources

[jbrandt]

Howdy!

I've created several reports on Desktop which successfully call an api using Web.MultiPartPost to construct, request and retrieve data from an on-line service.  However, publishing to PBI Serivce and attempting to refresh, I am informed that the data source does not support refreshes.   By contrast, I can construct a simple "Web.Contents" query, retrieving data which does support refreshes.  

Can anyone provide insights as to why one method would be supported and not the other?  Has anyone sucessfully published refreshing queries on Service using  a Post method? 

Thanks in advance!

[jbrandt · Accepted solution]

I think I've answered my own question here, so I'll post to share.  

First, a clarification.  Web.MultiPartPost is a function construct which incorporates Web.Contents but apparently obfuscates this fact to PBI Service, as it doesn't reconize it as a known connection type.   [I'm not sure who to attribute this function to, It's nice work, but I'm not the original author of it ] 

Regarding the inability to refresh the query using the MultiPartPost function.  Apparently the only non-DirectQuery connection type that will refresh in PBI Service is a Web.Contents call using Annonymous authentication.  I was able to refactor the function, eliminating much of the flexability, but creating a version that Service will recognize as supportable with Annonymous authentication.  That being said, you must reset the credentials after you (re)publish the dataset, even though it's just clicking through the Annonymous setting.  

I'll also note that the query still won't refresh in an Embedded scenario.  It seems in this case, no imported dataset can be refreshed (yet - hopefully!), only DirectQuery, e.g. to Azure SQL.