# System flow **URL:** \ **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:** 1\ **Showing post:** 2
**Author:** ![ThinhDinh](https://sea2.discourse-cdn.com/flex002/user_avatar/community.glideapps.com/thinhdinh/32/49_2.png) [@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… --- _[View the full topic](https://community.glideapps.com/t/system-flow/48631)._