> ## Documentation Index
> Fetch the complete documentation index at: https://docs.metrics-man.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Isnull

# \$isNull

The `$isNull` operator checks if a value is null.

## Input

* A single value of any type

## Output

* `true` if the input value is null, `false` otherwise

## Examples

### Check Null Value

```json theme={null}
{
  "$isNull": [
    null
  ]
}
```

Result: `true`

### Check Non-Null Value

```json theme={null}
{
  "$isNull": [
    "hello"
  ]
}
```

Result: `false`

### From Field

```json theme={null}
{
  "$isNull": [
    {
      "$input": "optional_field"
    }
  ]
}
```

Result: `true` if the optional\_field is null, otherwise `false`