# Is there any way to create input and output fields dynamically at runtime?

**URL:** https://forum.opentap.io/t/is-there-any-way-to-create-input-and-output-fields-dynamically-at-runtime/1996
**Category:** General
**Created:** [June 7, 2024, 5:48am UTC](https://forum.opentap.io/t/is-there-any-way-to-create-input-and-output-fields-dynamically-at-runtime/1996 "2024-06-07T05:48:20Z")
**Posts on this page:** 2
**Page:** 1

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### Author: ![saurav](https://avatars.discourse-cdn.com/v4/letter/s/6de8d8/32.png) [@saurav](https://forum.opentap.io/u/saurav)
#### Post date: [June 7, 2024, 5:48am UTC](https://forum.opentap.io/t/is-there-any-way-to-create-input-and-output-fields-dynamically-at-runtime/1996/1 "2024-06-07T05:48:20Z")

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Basically, I want to generate a variable number of input and output fields dynamically in the test step settings according to the user’s specified value. Is there any approach based on OpenTap UI for achieving this?

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### Author: ![btyilmaz](https://avatars.discourse-cdn.com/v4/letter/b/a3d4f5/32.png) [@btyilmaz](https://forum.opentap.io/u/btyilmaz)
#### Post date: [June 12, 2024, 8:04am UTC](https://forum.opentap.io/t/is-there-any-way-to-create-input-and-output-fields-dynamically-at-runtime/1996/2 "2024-06-12T08:04:09Z")

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Hi @saurav ,

I think you can add an input or an output to a test step using mixins. You need to develop a Mixin plugin and a MixinBuilder to achieve this. You can find details of mixins here: [Test Step | OpenTAP](https://doc.opentap.io/Developer%20Guide/Test%20Step/Readme.html#mixins)