# Ignition Designer - handling Null values

**URL:** <https://forum.inductiveautomation.com/t/ignition-designer-handling-null-values/117107>\
**Category:** Ignition\
**Created:** [September 16, 2026, 8:42pm UTC](https://forum.inductiveautomation.com/t/ignition-designer-handling-null-values/117107 "2026-09-16T20:42:06Z")\
**Posts on this page:** 6\
**Page:** 1

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**Author:** ![SgVal](https://avatars.discourse-cdn.com/v4/letter/s/a8b319/32.png) [@SgVal](https://forum.inductiveautomation.com/u/SgVal)\
**Post date:** [September 16, 2026, 8:42pm UTC](https://forum.inductiveautomation.com/t/ignition-designer-handling-null-values/117107/1 "2026-09-16T20:42:06Z")

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Hi all, I am new here and need help please.

I have this instance that uses UDT Definitions. The tag is a reference, type String, but sometimes it gets a "Null" value when it should be an empty string.

I created a workaround for one specific tag using the IsNull function, and it works well. However, there are hundreds of tags having the same issue.

Is there a way to create a function, condition, or something else within the UDT that would apply to all String tags at once, or would I need to do this directly on each tag? Any tips or suggestions will be appreciated.

Thank you!

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**Author:** ![JordanCClark](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/jordancclark/32/83362_2.png) [@JordanCClark](https://forum.inductiveautomation.com/u/JordanCClark)\
**Post date:** [September 16, 2026, 9:05pm UTC](https://forum.inductiveautomation.com/t/ignition-designer-handling-null-values/117107/2 "2026-09-16T21:05:16Z")

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Add an expression tag with a coalesce function to the UDT.

[coalesce | Ignition User Manual](https://www.docs.inductiveautomation.com/docs/8.3/appendix/expression-functions/logic/coalesce)

So, how I would modify the UDT definition:

- rename the reference tag (e.g. _ **myTag** _ -\> _ **myTag\_in** _)
- add an expression tag with the coalesce named _ **myTag** _`coalesce({[.]myTag_in}, '')`

coalesce() returns the first non-null value.

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<div class="post-metadata">

**Author:** ![SgVal](https://avatars.discourse-cdn.com/v4/letter/s/a8b319/32.png) [@SgVal](https://forum.inductiveautomation.com/u/SgVal)\
**Post date:** [September 16, 2026, 9:19pm UTC](https://forum.inductiveautomation.com/t/ignition-designer-handling-null-values/117107/3 "2026-09-16T21:19:46Z")

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Thanks!

That is pretty much what I have for the UDT tag except that I'm using IsNull, but I was wondering if there is other way to propagate or maybe a configuration that recognized empty string as empty instead of NULL.

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<div class="post-metadata">

**Author:** ![JordanCClark](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/jordancclark/32/83362_2.png) [@JordanCClark](https://forum.inductiveautomation.com/u/JordanCClark)\
**Post date:** [September 16, 2026, 9:41pm UTC](https://forum.inductiveautomation.com/t/ignition-designer-handling-null-values/117107/4 "2026-09-16T21:41:26Z")

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Ah. I think i may have misread. You have hundreds of strings in a single UDT?

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<div class="post-metadata">

**Author:** ![SgVal](https://avatars.discourse-cdn.com/v4/letter/s/a8b319/32.png) [@SgVal](https://forum.inductiveautomation.com/u/SgVal)\
**Post date:** [September 16, 2026, 9:58pm UTC](https://forum.inductiveautomation.com/t/ignition-designer-handling-null-values/117107/5 "2026-09-16T21:58:20Z")

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My mistake, I was not clear. There are hundreds of strings spread out on several UDTs. If there is a way to configure the UDT to handle the Null instead of a tag inside of UDT, it will be a lot easier to update the UDTs than each string tag in the UDT.

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**Author:** ![paul-griffith](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/paul-griffith/32/37249_2.png) [@paul-griffith](https://forum.inductiveautomation.com/u/paul-griffith)\
**Post date:** [September 16, 2026, 10:12pm UTC](https://forum.inductiveautomation.com/t/ignition-designer-handling-null-values/117107/6 "2026-09-16T22:12:10Z")

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There is not.