How to update table columns where some are null?

Basically I have Articles where some values might be null. For example, an Article may have an image attached to it or an excerpt applied.

Take a look at this screenshot:

The trouble is that when I want to edit a column that has null values and replace that with real values, it either updates the null columns or the columns that have real values depending on PATCH or PUT. It does not update both.

How can I update an Article in one request regardless if a column was initially null or not.

via Chebli Mohamed