New Column in modeling tab greyed out

[jasonreed247]

I created a table in Excel with the values of A, B, C in column A and 1, 2, 3 in Column B. I saved and closed this and then in Power BI used it to create a dataset. I used that dataset to create a small chart. I am able to create a third column and add it to the chart, in this case every value in the new column consistsis 1. I am able to save and publish that report.

If I start a new instance of Power BI and select the above dataset as the source I am able to re-create the same chart. However in the new instance I am unable to create a new column. When I right click the table name in Fields, New Measure is an option but not New Column. Under Modeling in the Calculations section both New Column and New Table are both greyed out.

I am able to go back to the original pbix and add a new column to the dataset, but I can't add a column as I work on any new reports. Eventually I'll have a bunch of reports utilizing a bnuch of datasets. Am I always supposed to go back to the original pbix to add a column? Is there any way for me to get New Column not greyed out as I develop more reports?

[TomMartens · Accepted solution]

Hey @jasonreed247 ,

Connecting to a Power BI dataset from Power BI Desktop instead of connecting to the original data source creates a "thin" report at least this is how these kind of reports are called.

This method is essential in separating the data and the content. As there are many advantages in following this development approach.

One of the downsides of this approach is that you cant change the underlying data model from inside one of these thin reports by creating a calculated columns. This can become a little cumbersome especially if there is only developer, and this developer creates the data model and the content.

Nevertheless, I always recommend to follow this approach as it comes with more advantages than disadvantages. And I also tend to avoid creating measures in the thins report as this spreads the data model across various Power BI files.

Hopefully, this answers your question.

Regards,

Tom