Creating Unique Serial Numbers in Forms

Last updated: 11 Jan 2022

There are times you may want to generate a unique serial number for each and every form in a project. This article discusses various workarounds on how to create unique serial numbers using the calculate question-type.

Approach 1: Creating Sequential Unique Serial Numbers Based on Date and Time

This method works best with Enketo web forms. It uses a calculation function to create a unique serial number based on the date and time to the first millisecond. Although this method may not meet all your needs, it should give you an illustration of how much you can stretch calculate functions.

Create a calculate question type in either the formbuilder or XLSForm and use the formula below.

concat(substr(today(), 0, 4), substr(today(), 5, 7), substr(today(), 8, 10), substr(now(), 11, 13), substr(now(), 14, 16), substr(now(), 17, 19))

The same formula can work as an integer question when working in an XLSForm.

In the example, when you preview the deployed form in Enketo, you should be able to see the serial number within the note question as shown in the image below:

Approach 2: Creating Unique Serial Numbers from Selected Variables

This example shows how to create unique serial numbers from existing, already defined variables in your form by using the concat() expression in a calculate question type. The example is shown as an XLSForm, but can just as easily be done within the formbuilder.

survey

type	name	label	calculation
text	Q1	Region Name
text	Q2	District Name
text	Q3	Cluster Name
text	Q4	Village Name
text	Q5	Household Serial Number
calculate	Q1_C		substr(${Q1}, 0, 3)
calculate	Q2_C		substr(${Q2}, 0, 3)
calculate	Q3_C		substr(${Q3}, 0, 3)
calculate	Q4_C		substr(${Q4}, 0, 3)
calculate	ID		concat(${Q1_C}, ‘-’, ${Q2_C}, ‘-’, ${Q3_C}, ‘-’, ${Q4_C}, ‘-’, ${Q5})
note	note_id	Your Unique ID for this form is: ${ID}

When you preview the example in Enketo web forms, the serial number will be presented within the note question as shown in the image below: