# Apply (regex) action to multiple fields at once?

**URL:** https://community.mp3tag.de/t/apply-regex-action-to-multiple-fields-at-once/71804
**Category:** Support
**Created:** [September 2, 2026, 11:42am UTC](https://community.mp3tag.de/t/apply-regex-action-to-multiple-fields-at-once/71804 "2026-09-02T11:42:07Z")
**Posts on this page:** 1
**Showing post:** 5

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### Author: ![Casual\_Tea](https://community.mp3tag.de/user_avatar/community.mp3tag.de/casual_tea/32/18886_2.png) [@Casual\_Tea](https://community.mp3tag.de/u/Casual_Tea)
#### Post date: [September 4, 2026, 11:54am UTC](https://community.mp3tag.de/t/apply-regex-action-to-multiple-fields-at-once/71804/5 "2026-09-04T11:54:23Z")

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Thank you for clarifying.

It's a pity that `$regexp()` always returns something (`$0` or in this case `%album%` when no match is found and the replacement when a match is found).

With my wordy and error prone workaround from [this thread](https://community.mp3tag.de/t/simple-way-to-abort-action-if-regex-does-not-match/66243), `$lower()` (and other string functions that do not have a regex internal replacement like `\l`) can be used without risking unwanted changes.

```auto
$if($neql($regexp(%album%,^(L).*,$1),%album%),$lower($regexp(%album%,^(L).*,$1)),%album%)

```

The check if the replacement is identical to the source field is needed because otherwise, `$lower()` would be applied to the source field in the case of no match as seen here:

Match:

 ![match](https://community.mp3tag.de/uploads/default/original/3X/b/1/b1b4000827a1cd6af02d5d505441b3db07c2cd30.png)  
No Match:  
 ![no match](https://community.mp3tag.de/uploads/default/original/3X/2/d/2d65fd05228b78c92ae32a1482a965a4ac4d7b48.png)

Which is why I still think it would be a good idea to either add a new string function that is identical to `$regexp()` except that it returns `false` when no match is found or to add a fifth parameter to `$regexp()` that changes the behavior from returning `$0` to `false` in the case of no match.

With such a new string function or with the addition of a fifth parameter, this **would** be a succinct solution for many problems that avoids maintaining the same regex twice:

 ![solution if false is returned](https://community.mp3tag.de/uploads/default/original/3X/b/d/bdc658ff45e9c4a91c701a58c45ee74ccfab01fb.png)

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_[View the full topic](https://community.mp3tag.de/t/apply-regex-action-to-multiple-fields-at-once/71804)._