> For the complete documentation index, see [llms.txt](https://help.claritylims.illumina.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://help.claritylims.illumina.com/api-and-database/api-docs/tips-and-tricks/updating-preset-value-of-a-step-udf-through-api.md).

# Updating Preset Value of a Step UDF through API

Use the API to update the preset value of a user-defined field (UDF)/custom field configured on a step.

From your test server:

1. GET a chosen UDF/custom field.
2. Do a PUT and include a new line.

For example, to add 'My new preset', insert the preset (My new preset), after your last value in your XML:

```
........

<preset>Your last preset</preset>

<preset>My new preset</preset>

<is-required>Your original value</is-required>

<attach-to-category>Your original value</attach-to-category>

</cnf:field>
```

This tool is powerful when integrating with external systems and combined with the Begin Work trigger. For example, it can be used to reach out to an external source with a script, initiated with the Begin Work trigger. The script makes sure that the presets for the Step Details UDFs/custom fields are always up to date and in sync with the server—before entering the Record Details screen.


---

# Agent Instructions
This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com.

## Querying This Documentation
If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter, and the optional `goal` query parameter:

```
GET https://help.claritylims.illumina.com/api-and-database/api-docs/tips-and-tricks/updating-preset-value-of-a-step-udf-through-api.md?ask=<question>&goal=<endgoal>
```

`ask` is the immediate question: it should be specific, self-contained, and written in natural language.
`goal` is optional and describes the broader end goal you are ultimately trying to accomplish on behalf of the user. GitBook uses it to tailor the answer towards what is most useful for that goal.

The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.