Add a calculated column to a dataflow

[ldwf]

I have created several PBI dataflows with the intention of having them feed a PBI datamart.  I want to create some calculated fields in the flow using DAX, just like I do on PBI desktop.  However, I don't seem to see an option that would allow me to create calculated fields using DAX.  I do see the option to create a measure in the datamart, but I don't see anything about calculated fields.  How would I be able to build calculated fields using DAX?

[Anonymous]

Hi @ldwf 

In Power BI dataflows, you can't create calculated fields using DAX directly as you do in Power BI Desktop. Dataflows use Power Query, which relies on M code for transformations and calculations

But unfortunately, there isn't a direct tool to convert DAX to M code.

Just as lbendlin posted that you'd better off re-implementing the business logic.

Otherwise you can only use M-code to rewrite your calculated column as a custom column manually, I believe this is a huge amount of work. 

Solved: Creating a calculated table in PowerBI Service dat... - Microsoft Fabric Community

Best Regards

Zhengdong Xu
If this post helps, then please consider Accept it as the solution to help the other members find it more quickly.

[lbendlin]

There is no need for DAX.  use Table.AddColumn in your Power Query M code.

[ldwf]

Some of the DAX code we build is quite extensive, i.e, like 50 or more lines for just one calculated column.  If I want to clone these calculated columns, do I need to rebuild all the DAX formulas in Power Query M code?

[lbendlin · Accepted solution]

Absolutely. Having these complex calculated columns in the first place is a design red flag. Don't forget -they eat up space AND compute when they are calculated.

[ldwf]

is there a tool for converting DAX to Power Query M?

[lbendlin]

Not that I am aware of. You are likely better off re-implementing the business logic.