> For the complete documentation index, see [llms.txt](https://cyr1en.gitbook.io/commandprompter/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://cyr1en.gitbook.io/commandprompter/features/input-validation.md).

# Input Validation

Input validation restricts prompt inputs using regular expressions, online player checks, or JavaScript expressions.

To use input validation:

1. Define a validator in `prompt-config.yml` under `Input-Validation`.
2. Apply it using the `-iv:<alias>` prompt flag.

***

## Validator Types

| Validator Type    | Config Key      | Description                                                  |
| ----------------- | --------------- | ------------------------------------------------------------ |
| **Regex**         | `Regex`         | Validates if the input matches a regular expression pattern. |
| **Online Player** | `Online-Player` | Validates if the input matches the name of an online player. |
| **JS Expression** | `JS-Expression` | Validates by evaluating a JavaScript expression.             |

***

## Configuration Example (`prompt-config.yml`)

```yaml
Input-Validation:
  Integer-Sample:
    Alias: is
    Regex: '^\d+'
    Err-Message: '&cPlease enter a valid integer!'
  Alpha-Sample:
    Alias: ss
    Regex: '[A-Za-z ]+'
    Err-Message: '&cInput must only consist of letters!'
  Online-Validator:
    Alias: ov
    Online-Player: true
    Err-Message: '&cThat player is not online!'
```

***

## Usage

Apply the validator to a prompt using `-iv:<alias>`:

```
/command <Enter integer -iv:is> <Enter letters -iv:ss> <Enter online player -iv:ov>
```

If validation fails, the `Err-Message` is sent to the player, and the prompt is re-displayed.

*Useful Resource: Learn more about* [*Regular Expressions*](https://github.com/Varunram/Awesome-Regex-Resources)*.*


---

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