Help needed to convert TMDL back to TMSL

[yazdanb]

Hi all,

Our team has some PowerBI reports (most are TMSL, a handful are TMDL). We noticed an issue in a TMDL model recently where some changes to our tables broke our Git Integration since updates could not be applied. The reason was that there were some table files that were no longer being used and they did not get automatically cleaned up/garbage collected. This was a dealbreaker for us to use TMDL going forward so I spoke with Microsoft and they confirmed the limitation:

"When a semantic model is stored using TMDL format, the model is represented as a folder structure with separate files per object (tables, partitions, variations, etc.). Unlike the legacy TMSL (model.bim) format—where the model is re‑serialized as a single file—TMDL does not automatically remove unused or orphaned table‑related files after structural or table‑level changes."

I understand that the change to TMDL is meant to be permanent. It is vital to our workflow and reporting that we are able to convert this back to TMSL. Can anyone please guide me on a workaround? There are only a few datasets that we would have to convert, which mitigates the issue to an extent. I am reading about ways to do this in Tabular Editor 3 or using the pbi-tools CLI but not sure about the reliability/accuracy of those suggestions.

Thank you!

[Deku · Accepted solution]

I've done this in the past when fabric API didn't support TMDL yet. AnalysisServices.Tabular has some serialisation functions you can use for the conversion.

 

[yazdanb]

Thank you! I found an easier solution in saving the dataset as PBIP (after turning off the TMDL preview feature in the desktop app) and then just adding those folders to the repo and updating throught Git Integration/Source Control in the workspace. It was able to recreate the reports in place without affecting our workspace-only report or connection bindings