Check if a barcode has been already scanned

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Fabien Cassan

Feb 22, 2016, 10:21:09 PM2/22/16
to Kobo Users
Dear all,

I would like to organize distribution lists management with Kobo by scanning barcodes present in the beneficiary card. However, i would like to check in real time (and not post treatment) if a barcode has already been scanned or not in order to avoid to have beneficiaries coming several times for the distribution.
Do you know if it is possible with Kobo?

Thanks in advance


Aloo Stephen

Feb 29, 2016, 8:13:12 AM2/29/16
This will require some tweeks into your coding as well as how well you work on coordinating your submission.

I rarely use the submission path that requires the servers; I prefer using dropbox for submission and scripting the data aggregation. This way I can accomplish similar tasks such as signing in someone into an event using barcodes and ensuring that within 10 seconds the code used is invalidated.

Step 1. You need to take advantage of the pull function of then forms it acts more like vlook up.
Step 2: Code to ensure that status is updated. 

PS. am writting from the phone let me type this more elaborately later on.

S. Aloo

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Fabien Cassan

Mar 2, 2016, 8:53:44 PM3/2/16
Thanks a lot for your feedback. Waiting then for your additional infos later on.


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Feb 15, 2018, 3:33:28 AM2/15/18
to KoBoToolbox Users
Dear Fabien, Dear Aloo

I know this has been a while now, but did you find a solution for this? I have exactly the same problem: I want to scan a barcode and get a constraint message if the barcode has already been scanned within the same survey.


joseph Aghatise

Mar 6, 2018, 4:47:23 AM3/6/18
to KoBoToolbox Users
Pull a file and write for example a Yes or No to status. Then work your code to verify if status is No, show scan barcode otherwise display error message and proceed to next question.

Here is how we used this feature. 

1.   File containing details of beneficiaries was uploaded to xlsform
2.  The field officer search for beneficiary using their beneficiary code
3.  Field officer complete a questionnaire and scan code on beneficiary card
4.  If a constraint field already has a Yes, a warning message is displayed to the user and survey ends otherwise a Yes is written to a column and user continue.

Hope this is helpful. You may also share your code so we can update and send back to you.

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