How to retain hover functionality on Person column value when using column formatting and txtContent?

Question

A Person column, with no column formatting, has the desired functionality.

I.e. when you hover over a person's name, you can see their Person card etc.

So the starting state of the column formatting is:

{
  "$schema": "https://developer.microsoft.com/json-schemas/sp/v2/column-formatting.schema.json"
}

Then I add additional column formatting, with an if condition.

{
  "$schema": "https://developer.microsoft.com/json-schemas/sp/v2/column-formatting.schema.json",
  "elmType": "div",
  "txtContent": "=if([$Current_x0020_Assignment] =='', 'Not assigned', [$Current_x0020_Assignment.title])"
}

The logic above is saying:

When the value of the Current Assignment column is blank, add the text Not assigned,
otherwise, show the the Person's name.

What happens is that the text displays correctly, but I lose the 'hover' functionality that displays the Person card etc.

If I try referencing @currentField:

{
  "$schema": "https://developer.microsoft.com/json-schemas/sp/v2/column-formatting.schema.json",
  "elmType": "div",
  "txtContent": "=if([$Current_x0020_Assignment] =='', 'Not assigned', @currentField)"
}

or [$Current_x0020_Assignment]:

{
  "$schema": "https://developer.microsoft.com/json-schemas/sp/v2/column-formatting.schema.json",
  "elmType": "div",
  "txtContent": "=if([$Current_x0020_Assignment] =='', 'Not assigned', [$Current_x0020_Assignment])"
}

The Person column just displays [Object Object].

Is there a way to apply the desired conditional logic whilst retaining the hover functionality when hovering over the Person's name?

Answer 1

Per this answer, just defining the defaultHoverField property seems to work, ie:

{
  "$schema": "https://developer.microsoft.com/json-schemas/sp/v2/column-formatting.schema.json",
  "elmType": "div",
  "txtContent": "=if([$Current_x0020_Assignment] =='', 'Not assigned', [$Current_x0020_Assignment.title])",
  "defaultHoverField": "[$Current_x0020_Assignment]" 
}

Interestingly, the hover functionality is automatically not applied to the Not assigned text values, which is great (i.e., I don't need to apply extra conditional structures to handle that scenario).