The SearchProvider class

The SearchProvider class executes searches for specific types of items, and manages thumbnails, descriptions, and sub-filters.

It has the following basic API:

public class SearchProvider
{
    public SearchProvider(string id, string displayName = null);

    // Creates an Item bound to this provider.
    public SearchItem CreateItem(string id, string label = null, string description = null, Texture2D thumbnail = null);

    // Utility functions to check whether the search text matches a string.
    public static bool MatchSearchGroups(string searchContext, string content);
    public static bool MatchSearchGroups(string searchContext, string content,
                                        out int startIndex, out int endIndex);

    // The provider's unique ID.
    public NameId name;
    // Text token to "filter" a provider (for example, "me:", "p:", and "s:").
    public string filterId;
    // This provider is only active when a search explicitly specifies it with
    // its filterId.
    public bool isExplicitProvider;
    // Handler to fetch and format the label of a search item.
    public FetchStringHandler fetchLabel;
    // Handler to provide an async description for an item. Called just before
    // Search displays the item.
    // Allows a plug-in provider to fetch long descriptions only when
    // Search needs them.
    public FetchStringHandler fetchDescription;
    // Handler to provider an async thumbnail for an item. Called just before
    // Search displays the item.
    // Allows a plug-in provider to fetch/generate previews only when
    // Search needs them.
    public PreviewHandler fetchThumbnail;
    // Handler to support drag interactions. It is up to the SearchProvider
    // to properly set up the DragAndDrop manager.
    public StartDragHandler startDrag;
    // Called when the selection changes and Search can track it.
    public TrackSelectionHandler trackSelection;
    // MANDATORY: Handler to get items for a search context.
    public GetItemsHandler fetchItems;
    // A Search Provider can return a list of words that help the user complete
    // their search query.
    public GetKeywordsHandler fetchKeywords;
    // List of sub-filters that are visible in the FilterWindow for a
    // SearchProvider (see AssetProvider for an example).
    public List<NameId> subCategories;
    // Called when the Search window opens. Allows the Provider to perform
    // some caching.
    public Action onEnable;
    // Called when the Search window closes. Allows the Provider to release
    // cached resources.
    public Action onDisable;
    // Int to sort the Provider. Affects the order of search results and the
    // order in which providers are shown in the FilterWindow.
    public int priority;
    // Called when Search opens in "contextual mode". If you return true
    // it means the provider is enabled for this search context.
    public IsEnabledForContextualSearch isEnabledForContextualSearch;
}

Caching and releasing resources

When you launch the Search window, it calls onEnable, which you can use to cache resources.

When you close the Search window, it calls onDisable, which you can use to release resources.

Initialization

Because the Search item list uses a virtual scrolling algorithm, some SearchItem fields (for example, label, thumbnail, and description) are fetched on demand, if they are not already provided.

To populate those fields after the items are created, you need to initialize the SearchProvider with specific handlers (fetchLabel, fetchDescription, fetchThumbnail).

Tracking item selection

You can register a callback on trackSelection to have Search do something whenever you select an item in the search results using the mouse or the keyboard. For example, the AssetAny media or data that can be used in your game or project. An asset may come from a file created outside of Unity, such as a 3D Model, an audio file or an image. You can also create some asset types in Unity, such as an Animator Controller, an Audio Mixer or a Render Texture. More info
See in Glossary and SceneA Scene contains the environments and menus of your game. Think of each unique Scene file as a unique level. In each Scene, you place your environments, obstacles, and decorations, essentially designing and building your game in pieces. More info
See in Glossary providers use the trackSelection callback to ping the selected item in Search.

Enabling drag and drop

Some Search Providers return items that you can drag and drop into the Scene. If you are creating a custom provider whose items support drag and drop, implement startDrag.

For example, the Asset and Scene providers populate the DragAndDrop structure with the relevant item UIDs to allow proper drag and drop interactions.

Including a provider in a contextual search

When you open the Search window with the Alt Shift + C shortcut, it starts a contextual search, meaning Search searches the window that has focus.

When you launch a contextual search, providers that override isEnabledForContextualSearch check to see if they should be enabled, as in the following example:

// Taken from Scene hierarchy provider:
// Makes the provider part of the contextual search if the Scene view or the
// Hierarchy window has focus.
isEnabledForContextualSearch = () =>
                QuickSearchTool.IsFocusedWindowTypeName("SceneView") ||
                QuickSearchTool.IsFocusedWindowTypeName("SceneHierarchyWindow");