# Graph > Represents the core definition of a graph and defines its behavior. ## Definition * **Type:** Class * **Namespace:** [Unity.GraphToolkit.Editor](/engine/6000.5/script-reference/unity/graphtoolkit/editor.md) * **Assembly:** UnityEditor ```csharp public class Graph ``` ## Remarks `Graph` serves as the central entry point for: * Lifecycle management (via [Graph.OnEnable](/engine/6000.5/script-reference/unity/graphtoolkit/editor/graph/onenable.md), [Graph.OnDisable](/engine/6000.5/script-reference/unity/graphtoolkit/editor/graph/ondisable.md)) * Change tracking (via [Graph.OnGraphChanged](/engine/6000.5/script-reference/unity/graphtoolkit/editor/graph/ongraphchanged.md)) * Access to nodes and variables To register a graph type and associate it with a custom file extension and configuration options, apply the [GraphAttribute](/engine/6000.5/script-reference/unity/graphtoolkit/editor/graphattribute.md) to your custom `Graph` class. You can further control the graph's behavior using the [GraphOptions](/engine/6000.5/script-reference/unity/graphtoolkit/editor/graphoptions.md) enum, which defines traits such as support for subgraphs. If your graph supports subgraphs (via [GraphOptions.SupportsSubgraphs](/engine/6000.5/script-reference/unity/graphtoolkit/editor/graphoptions/supportssubgraphs.md)), you can declare valid subgraph types using the [SubgraphAttribute](/engine/6000.5/script-reference/unity/graphtoolkit/editor/subgraphattribute.md). Use the [GraphDatabase](/engine/6000.5/script-reference/unity/graphtoolkit/editor/graphdatabase.md) utility class to create, load, and save graph assets in the Unity Editor. Graphs are serialized assets. You can create them through the editor UI with [GraphDatabase.PromptInProjectBrowserToCreateNewAsset](/engine/6000.5/script-reference/unity/graphtoolkit/editor/graphdatabase/promptinprojectbrowsertocreatenewasset.md) or load them from disk with [GraphDatabase.LoadGraph](/engine/6000.5/script-reference/unity/graphtoolkit/editor/graphdatabase/loadgraph.md). ## Properties | Property | Description | | ------------------------------------------------------------------------------------------------- | ------------------------------------------------------------------------------------------------------------------------- | | [Name](/engine/6000.5/script-reference/unity/graphtoolkit/editor/graph/name.md) | The name of the graph. | | [NodeCount](/engine/6000.5/script-reference/unity/graphtoolkit/editor/graph/nodecount.md) | The number of [INode](/engine/6000.5/script-reference/unity/graphtoolkit/editor/inode.md)s in the graph. | | [VariableCount](/engine/6000.5/script-reference/unity/graphtoolkit/editor/graph/variablecount.md) | The number of [IVariable](/engine/6000.5/script-reference/unity/graphtoolkit/editor/ivariable.md)s declared in the graph. | ## Methods | Method | Description | | ----------------------------------------------------------------------------------------------------------------------------- | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | [AddNode](/engine/6000.5/script-reference/unity/graphtoolkit/editor/graph/addnode.md) | Adds a node to the Graph. | | [AddSubgraphNode](/engine/6000.5/script-reference/unity/graphtoolkit/editor/graph/addsubgraphnode.md) | Creates and adds a new subgraph node referencing an existing Graph asset. | | [AddVariableNode](/engine/6000.5/script-reference/unity/graphtoolkit/editor/graph/addvariablenode.md) | Creates and adds a new variable node referencing an existing variable. | | [Connect](/engine/6000.5/script-reference/unity/graphtoolkit/editor/graph/connect.md) | Creates a wire connection between two ports. | | [CreateConstantNode](/engine/6000.5/script-reference/unity/graphtoolkit/editor/graph/createconstantnode.md) | Creates and adds a new constant node to the graph. | | [CreateLocalSubgraphNode](/engine/6000.5/script-reference/unity/graphtoolkit/editor/graph/createlocalsubgraphnode.md) | Creates and adds a new local subgraph node. | | [CreateVariable](/engine/6000.5/script-reference/unity/graphtoolkit/editor/graph/createvariable.md) | Creates and adds a new variable to the graph. | | [Disconnect](/engine/6000.5/script-reference/unity/graphtoolkit/editor/graph/disconnect.md) | Removes the wire connection between two ports. | | [GetNode](/engine/6000.5/script-reference/unity/graphtoolkit/editor/graph/getnode.md) | Retrieves a node defined in the graph by its index. | | [GetNodes](/engine/6000.5/script-reference/unity/graphtoolkit/editor/graph/getnodes.md) | Retrieves all nodes in the graph. | | [GetVariable](/engine/6000.5/script-reference/unity/graphtoolkit/editor/graph/getvariable.md) | Retrieves a variable declared in the graph by index. | | [GetVariables](/engine/6000.5/script-reference/unity/graphtoolkit/editor/graph/getvariables.md) | Retrieves all variables declared in the graph. | | [OnDefineSubgraphNodeOptions](/engine/6000.5/script-reference/unity/graphtoolkit/editor/graph/ondefinesubgraphnodeoptions.md) | Called to define the [INodeOption](/engine/6000.5/script-reference/unity/graphtoolkit/editor/inodeoption.md)s available on subgraph nodes that reference this type of graph. Similar in function to [Node.OnDefineOptions](/engine/6000.5/script-reference/unity/graphtoolkit/editor/node/ondefineoptions.md). | | [OnDisable](/engine/6000.5/script-reference/unity/graphtoolkit/editor/graph/ondisable.md) | Called when the graph is unloaded, or goes out of scope in the editor. | | [OnEnable](/engine/6000.5/script-reference/unity/graphtoolkit/editor/graph/onenable.md) | Called when the graph is created or loaded in the editor. | | [OnGraphChanged](/engine/6000.5/script-reference/unity/graphtoolkit/editor/graph/ongraphchanged.md) | Called after the graph has changed. | | [RemoveNode](/engine/6000.5/script-reference/unity/graphtoolkit/editor/graph/removenode.md) | Removes a node from the Graph. | | [RemoveVariable](/engine/6000.5/script-reference/unity/graphtoolkit/editor/graph/removevariable.md) | Removes a variable from the Graph. | | [UndoBeginRecordGraph](/engine/6000.5/script-reference/unity/graphtoolkit/editor/graph/undobeginrecordgraph.md) | Signals the beginning of an undoable operation. | | [UndoEndRecordGraph](/engine/6000.5/script-reference/unity/graphtoolkit/editor/graph/undoendrecordgraph.md) | Signals the end of an undoable operation. Sends the undo data to the editor undo system and refreshes the graph view with the changes made. |