How to Clear a Column with Patch and Blank in Power Apps
To empty a column, patch Blank() into it. Microsoft's reference: Blank returns a blank value, "use this to store a NULL value in a data source that supports these values, effectively removing any value from the field" (Blank function).
Prerequisites
- A Patch that updates an item (How to Create or Update a SharePoint List Item with Patch).
- Formula-level error management turned on. Microsoft's error-handling guidance: with it on, "you can write null or blank values to data sources". It's on by default for new apps; check Settings → Updates → Retired, where Disable formula-level management should be off (Error handling).
Example: Clear a Decline When a Response Is Sent Again
In the Career Development Plan app, a manager can decline a response with a comment and a review date. When the employee changes it and sends it again, it's waiting for review again, so the old comment and date no longer apply. The Patch clears both:
Status: {Value: StatusPending},
ManagerComment: Blank(),
SubmittedOn: Now(),
ReviewedOn: Blank()
ManagerComment is a multi-line text column and ReviewedOn a date and time column; Blank() clears both kinds.
The Result
The item's version history in SharePoint shows it. Version 2.0 is the manager's decline, with a comment and a review date. Version 3.0 is the employee's new send: ManagerComment and ReviewedOn are listed with no value:
Reading the item back through SharePoint's API gave null for both columns.
Blank or Empty Text?
"" is an empty string; Blank() is no value at all. Power Apps' IsBlank treats both as blank (IsBlank vs IsEmpty), but for a date column only Blank() makes sense.
Common Mistakes
| Mistake | What happens | Do this instead |
|---|---|---|
| Leaving the column out of the Patch | It keeps its old value | Set it to Blank() |
"" for a date column | It isn't a date | Blank() |
| Clearing a required column | SharePoint rejects the save | Only clear columns that aren't required |
Troubleshooting
| Symptom | Likely cause | Fix |
|---|---|---|
| The value isn't cleared | Formula-level error management is off | Turn it on in Settings |
| An error about a required column | The column is required in the list | Give it a value instead |
FAQ
Can I clear a variable the same way?
Yes: Set(x, Blank()), as Microsoft's data types article shows.
Does Blank() work for Choice columns?
The example only clears text and date columns, so it doesn't show that.
Conclusion
Patch Column: Blank() to remove a value, with formula-level error management on. Check the result in the item's version history or by reading it back.
