If you use Microsoft Power Automate with Microsoft SharePoint Online list or library data and need to check if a field is empty or null, you can use the @empty function in an expression.
Example
The following example involves setting up a new Power Automate workflow triggered when a user starts the workflow from the SharePoint list. The workflow will check if the President column is empty and update the Is Empty column with the result.
Create a SharePoint List

- Create a new SharePoint list. This demo uses the default Title column, a choice column called **President**, and a Boolean column called "Is Empty."
- Add some sample data. Leave the President column blank for some items.
Create a Power Automate Flow

- Create a new Power Automate Automated Cloud Flow. Select For a selected item as the trigger action. Select your SharePoint site and list in this action.
- Add the Get Item action and configure it to retrieve the selected item from the list. This step is necessary to retrieve all the columns so we can use them in the workflow. Set the ID to the ID of the For a Selected Item trigger.
- Add the Initialize Variable action. We want to use the empty() function with our President column in the Value. The full expression is :
empty(outputs('Get\_item')?['body/President/Value'])

- Add an Update Item action that is pointed to your list and set the Is Empty column.

Test your workflow
- Now, go back to your list and select an item with an empty President value. Under the Automate menu, you should see your workflow listed (it may take a few seconds to load). Please select it and run the workflow.

- Refresh your list after a few seconds; the Is Empty column should be checked.
- Try running the workflow on a row that has a President selected. The Is Empty should not be checked.

- Open the workflow that you ran. You can see that the variable we created resulted in True when the column was empty and False when it was not.