# IQueryHandler<TData, TPayload>

> Interface for query handlers.

## Definition

* **Type:** Interface
* **Namespace:** [UnityEditor.Search](/engine/6000.5/script-reference/unityeditor/search.md)
* **Assembly:** UnityEditor

```csharp
public interface IQueryHandler<TData, in TPayload> where TPayload : class
```

## Methods

| Method                                                                            | Description                                                        |
| --------------------------------------------------------------------------------- | ------------------------------------------------------------------ |
| [Eval](/engine/6000.5/script-reference/unityeditor/search/iqueryhandler2/eval.md) | Implement this function to evaluate the query on a single element. |