topic Re: dataflow - if there is a row present in Data Engineering

dataflow - if there is a row present

arkiboys2 — Wed, 06 Nov 2024 09:27:28 GMT

hello,

in the dataflow gen2, there are several steps from navigation of the source all the way to pivot column.

After the pivot, the step is to rename column. But the flow fails on this rename step because if there is no data then the step fails as the column does not exists

Any suggestions ?

thank you

Re: dataflow - if there is a row present

lbendlin — Wed, 06 Nov 2024 12:44:30 GMT

use try ... otherwise ... to decide what to produce in this scenario.

Re: dataflow - if there is a row present

arkiboys2 — Wed, 06 Nov 2024 13:22:29 GMT

you mean to have try catch inside dataflow gen2? is this the only way?

how is this possible?

thanks

Re: dataflow - if there is a row present

frithjof_v — Wed, 06 Nov 2024 18:32:06 GMT

You could add a dummy row.

However, do you want the dataflow to succeed if there is no data?

Re: dataflow - if there is a row present

frithjof_v — Wed, 06 Nov 2024 18:39:09 GMT

If you want to do the try ... otherwise ... logic instead of adding a dummy row, there is a description in the link. I can actually recommend to go through all the parts of this series if you have the time:

https://bengribaudo.com/blog/2020/01/15/4883/power-query-m-primer-part-15-error-handling

I've done most of the parts, but I skipped the last ones as I didn't feel they were so relevant for my use cases at the time.

I don't think there are so many users who have gone through this series, but it gives a great theoretical description (and also many practical examples!) of the Power Query M language. If you have the time. I had already worked 3 years with Power BI/Power Query before I did this series.

Re: dataflow - if there is a row present

arkiboys2 — Wed, 06 Nov 2024 18:52:46 GMT

yes to succeed if there is no row. thanks

Re: dataflow - if there is a row present

frithjof_v — Wed, 06 Nov 2024 18:58:14 GMT

I would add a dummy row with the necessary columns before that step, so that the step doesn't fail, and then I would filter away the dummy row afterwards.

Re: dataflow - if there is a row present

Anonymous — Thu, 07 Nov 2024 02:32:49 GMT

Hi @arkiboys2

If you use Table.RenameColumns to rename columns, a simple solution is to add MissingField.Ignore at the end. MissingField.Type - PowerQuery M | Microsoft Learn

Best Regards,
Jing
If this post helps, please Accept it as Solution to help other members find it. Appreciate your Kudos!

Re: dataflow - if there is a row present

arkiboys2 — Thu, 07 Nov 2024 14:59:13 GMT

I created a HelperRow which only has columns and no rows.

Then after the pivot step, I appended this helper row.

It seems fine now

thank you

Re: dataflow - if there is a row present

arkiboys2 — Thu, 14 Nov 2024 02:47:53 GMT

Thankyou