How do I use REGEXTRACT to return grouped numbers from a string where the number of groups varies?

Question

In Google Sheets, I'm trying to return numbers from within a text string.

The numbers are values of the property named either item_id or item_ids.

I've tried the REGEXTRACT function but I'm struggling.

Example 1

1.   Text in cell A1

   <!-- wp:shortcode -->
   [aces-unit-1 item_id=""1236""]
   <!-- /wp:shortcode -->
   

2.   Expected Result

   1236
   

Example 2

1.   Text in cell A1

   <!-- wp:shortcode -->
   [aces-bonuses-1 items_number=""4"" external_link=""1"" category="""" items_id=""1563, 2372, 3855, 3980"" exclude_id="""" parent_id="""" columns=""4"" order="""" orderby="""" title=""""]
   <!-- /wp:shortcode -->
   

2.   Expected Result

   1563, 2372, 3855, 3980
   

Answer 1

Formula

=REGEXEXTRACT(A1, "items?_id=""""((?:\d{4}[,\s]{0,2})+)""""")

Explanation

1. Matches (non-capture) (?:) 4-digit number groups \d{4} followed by 0-2 commas and/or spaces [,\s]{0,2}
2. Captures one or more of the matched number groups if immediately preceded by items?_id="""" and immediately followed by """""
   • the letter s is optional (item vs. items) s?
   • The consecutive (double) quotes "" are each escaped with an additional quote """"

#N/A Errors

If there is no match found, the formula returns a #N/A error. This can be handled using the IFNA function to return a blank of whatever value is preferred.

# IFNA returns nothing/blank 
=IFNA(REGEXEXTRACT(A1, "items?_id=""""((?:\d{4}[,\s]{0,2})+)"""""))

# IFNA returns something
=IFNA(REGEXEXTRACT(A1, "items?_id=""""((?:\d{4}[,\s]{0,2})+)"""""),<something>)

// Replace <something> with a string, number, cell reference, formula, etc. 

ARRAYFORMULA IFNA