# OnValidate()

> Editor-only function that Unity calls when the script is loaded or a value changes in the Inspector.

## Definition

* **Type:** Method
* **Namespace:** [UnityEngine](/engine/6000.0/script-reference/unityengine.md)

```csharp
public void OnValidate()
```

### Remarks

Use this to perform an action after a value changes in the Inspector; for example, making sure that data stays within a certain range. `OnValidate` is called at various stages during the Editor's normal operation, such as loading scenes, building a Player, and entering Play mode. `OnValidate` can be called often when the user interacts with an Inspector in the Editor. It can also be called from threads other than Unity's main thread, such as the loading thread. For these reasons, only use `OnValidate` to validate the data that changed. Don't use it to do other tasks such as creating objects or calling other non-thread-safe Unity API. You can't reliably perform Camera rendering operations from `OnValidate`. Instead, add a listener to [EditorApplication.update](/engine/6000.0/script-reference/unityeditor/editorapplication/update.md), and perform the rendering during the next Editor Update call. Additional Resources: [EditorApplication.update](/engine/6000.0/script-reference/unityeditor/editorapplication/update.md), [EditorApplication.delayCall](/engine/6000.0/script-reference/unityeditor/editorapplication/delaycall.md).

### Examples

```csharp

using UnityEngine;

public class Health : MonoBehaviour
{
    [SerializeField]
    private int maxHealth = 100;

    [SerializeField]
    private int currentHealth = 100;

    // Called in editor when values are changed in Inspector
    private void OnValidate()
    {
        // Ensure maxHealth is at least 1
        if (maxHealth < 1)
            maxHealth = 1;

        // Clamp currentHealth between 0 and maxHealth
        currentHealth = Mathf.Clamp(currentHealth, 0, maxHealth);
    }
}
```