# System flow
**URL:** https://community.glideapps.com/t/system-flow/48631
**Category:** Ask for Help
**Created:** [September 5, 2022, 1:44pm UTC](https://community.glideapps.com/t/system-flow/48631 "2022-09-05T13:44:52Z")
**Posts on this page:** 2
**Page:** 1
### Author:  [@Alisa\_Rahim](https://community.glideapps.com/u/Alisa_Rahim)
#### Post date: [September 5, 2022, 1:44pm UTC](https://community.glideapps.com/t/system-flow/48631/1 "2022-09-05T13:44:52Z")
Hi, anyone can help me? i make some sequence to my apps like below flow :
scan barcode \> if already scan pop up noti
if not scan \> add row
but the action not work, i already change many situation in the action. pls help me.!
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### Author:  [@ThinhDinh](https://community.glideapps.com/u/ThinhDinh)
#### Post date: [September 6, 2022, 12:48am UTC](https://community.glideapps.com/t/system-flow/48631/2 "2022-09-06T00:48:06Z")
I don’t have that much experience with scanning barcodes, but I believe it’s an action itself, so you can’t add branches of logic after that action, in a custom action chain, as of now.
I believe what you can do for now is:
- Add a button to scan the barcode and write it to a column.
- Use a relation to determine if the barcode has been added or not. If added, show a hint that it has been added. If not, show a button to add a new row with that code.
That should be done in a custom form environment.
> [@How do I create a custom form?](https://community.glideapps.com/t/how-do-i-create-a-custom-form/25014/):
>
> I’m just dropping this here so I have something to refer people to when they ask. This is a simple concept app (copyable), that demonstrates the following techniques: Building custom forms for adding and editing list items (as an alternative to the native forms provided by Glide) Preventing duplicate new entries using [User Specific Columns](https://docs.glideapps.com/all/reference/data-editor/user-specific-columns) and [Relations](https://docs.glideapps.com/all/reference/data-editor/computed-columns/relation-column) Enforcing mandatory input items The use of visibility conditions and user specific booleans to control user flow There is nothing particula…