> ## Documentation Index
> Fetch the complete documentation index at: https://hellocsv.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# Validators

This section describes the available validation rules.

## required

**Description:**\
Ensures the field is not empty.

**Additional:**\
Accepts an optional `error` message.
Additionally, accepts a `when` function that returns a boolean value. If the function returns false, the validation is skipped. Defaults to `() => true`.

Example:

```ts theme={null}
{
  "validate": "required",
  "when": (row) => row['employee.type'] === 'other'
}
```

***

## unique

**Description:**
Ensures the value is unique across rows.

**Additional:**
Accepts an optional `error` message.

***

## regex\_matches

**Description:**\
Validates a field against a regular expression.

**Additional:**\
Expects a `regex` and an optional `error` message.

***

## includes

**Description:**\
Checks if a value is within a predefined list.

**Additional:**\
Requires a list of valid values.

***

## multi\_includes

**Description:**\
Checks if all delimited values are valid.

**Additional:**\
Accepts `values`, a `delimiter`, and an optional `error` message.

***

## is\_integer

**Description:**\
Validates that the value is an integer.

**Additional:**\
Optional `error` message.

***

## phone\_number

**Description:**\
Validates phone number formatting.

**Additional:**\
Optional `error` message.

***

## email

**Description:**\
Validates email format.

**Additional:**\
Optional `error` message.

***

## postal\_code

**Description:**\
Validates postal code format.

**Additional:**\
Optional `error` message.

***

## custom

**Description:**\
Custom validation function.

**Additional:**\
Requires a `key` and a `validateFn` that returns an error message if validation fails.