# Disallowing Null Property Values

Without preventing it using the schema itself, `null` values for a property are not allowed. You can combine the validation type (e.g. `"string"` for the `orderNote` in the example below) with an additional allowance for `"null"`, as shown.

{% code title="Data Schema Example" lineNumbers="true" %}

```json
{
  "primaryKey": "orderNumber",
  "type": "object",
  "properties": {
    "orderNumber": {
      "type": "number",
      "minLength": 3
    },
    "customerName": {
      "type": "string",
      "minLength": 1
    },
    "orderNote": {
      "type": [
        "string",
        "null"
      ]
    }
  },
  "required": [
    "orderNumber", 
    "customerName"
  ],
  "additionalProperties: false
}
```

{% endcode %}