> For the complete documentation index, see [llms.txt](https://docs.jetadmin.io/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.jetadmin.io/faq-and-troubleshooting/how-to-restrict-input-in-a-text-field.md).
# How to restrict input in a text field?
If you want to allow an input to only receive a certain number or text format, you can use regular expressions.
For example, let's say that you want your input to receive an ID number that is structured like this: “010.124.501-55”. If you don’t know how to write regular expressions, you can simply ask any AI bot to do this for you, [ChatGPT](https://chat.openai.com/) for example:
After you get your regular expression, you can input it in the validation field of your component. Click on the component in builder -> Display tab -> Validate -> Use Regular expression
You can also mention your field format in the custom validation error field for easier understanding.
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