Descriptions can be added to the measures and columns of a data model to aid users during report development. Once descriptions have been applied and the dataset has been published to the Power BI service, users connected to the dataset via reports can view the descriptions as they hover over the fields in the fields list. This feature is particularly useful in communicating the business logic contained in measures, such as whether discounts are included or excluded in the Internet Net Sales measure.
Although field descriptions are recommended, particularly for measures that contain custom or complex logic, they are not a substitute for the formal documentation of a dataset. In most scenarios, the field description will only be used as a convenient reminder of the essential logic or meaning and thus can be more concise than the official corporate definition of the column or measure. A detailed example of developing documentation reports of a Power BI Dataset via
Dynamic Management Views (
DMVs) and Power BI Desktop can be found in Chapter 10 of
Microsoft Power BI Cookbook (
https://www.packtpub.com/big-data-and-business-intelligence/microsoft-power-bi-cookbook) by
Packt Publishing.
In the following example, a report author is connected to a published Power BI dataset and has hovered over the Internet Gross Product Margin measure:
Field Descriptions as Tooltips in the fields list
The descriptions can only be viewed from Power BI Desktop or the Power BI service. Users connecting to the dataset from Excel via the Power BI Publisher for Excel can't see the descriptions. Additionally, field descriptions are exclusive to the fields list and are not displayed in visuals on the report canvas.
Chapter 5,
Creating and Formatting Power BI Reports, contains additional information on Power BI reports created via Live connections to published Power BI datasets.
Descriptions can be applied by enabling the FIELD PROPERTIES pane from the View tab in the Report View. In the following screenshot, the FIELD PROPERTIES pane exposes the Name and Description of the selected measure (Internet Gross Product Margin):
FIELD PROPERTIES pane
Users connected to the dataset via Live connections can view the descriptions via the FIELD PROPERTIES pane. In this context, the Name and Description properties are read-only.
DMVs can be used to retrieve the descriptions applied to measures and columns of a dataset. With the dataset open in Power BI Desktop, the user can connect from a client application, such as DAX Studio, to execute the relevant DMV. The Description field of both the MDSCHEMA_MEASURES and the TMSCHEMA_MEASURES DMVs contains the description that has been applied to DAX Measures. The Description field in the TMSCHEMA_COLUMNS DMV provides the description applied to columns.
