TreeNodeSchemaClass Interface

Packages > @fluidframework/tree > TreeNodeSchemaClass

Tree node schema which is implemented using a class.

Signature

/** @sealed */
export interface TreeNodeSchemaClass<out Name extends string = string, out Kind extends NodeKind = NodeKind, out TNode = unknown, in TInsertable = never, out ImplicitlyConstructable extends boolean = boolean, out Info = unknown> extends TreeNodeSchemaCore<Name, Kind, ImplicitlyConstructable, Info>

Extends: TreeNodeSchemaCore <Name, Kind, ImplicitlyConstructable, Info>

Type Parameters

Remarks

Instances of this class are nodes in the tree. This is also a constructor so that it can be subclassed.

Using classes in this way allows introducing a named type and a named value at the same time, helping keep the runtime and compile time information together and easy to refer to un a uniform way. Additionally, this works around https://github.com/microsoft/TypeScript/issues/55832 which causes similar patterns with less explicit types to infer “any” in the d.ts file.

When sub-classing a a TreeNodeSchemaClass, some extra rules must be followed:

• Only ever use a single class from the schema’s class hierarchy within a document and its schema. For example, if using object(name, fields) you can do:

// Recommended "customizable" object schema pattern.
class Good extends schemaFactory.object("A", {
	exampleField: schemaFactory.number,
}) {
	public exampleCustomMethod(): void {
		this.exampleField++;
	}
}

But should avoid:

// This by itself is ok, and opts into "POJO mode".
const base = schemaFactory.object("A", {});
// This is a bad pattern since it leaves two classes in scope which derive from the same SchemaFactory defined class.
// If both get used, its an error!
class Invalid extends base {}

• Do not modify the constructor input parameter types or values:

class Invalid extends schemaFactory.object("A", {
	exampleField: schemaFactory.number,
}) {
	// This Modifies the type of the constructor input.
	// This is unsupported due to programmatic access to the constructor being used internally.
	public constructor(a: number) {
		super({ exampleField: a });
	}
}

Construct Signatures

Construct Signature Details

new (data: TInsertable | InternalTreeNode): Unhydrated<TNode>

Constructs an Unhydrated node with this schema.

Signature

/** @sealed */
new (data: TInsertable | InternalTreeNode): Unhydrated<TNode>;

Remarks

This constructor is also used internally to construct hydrated nodes with a different parameter type. Therefore, overriding this constructor with different argument types is not type-safe and is not supported.

Parameters

Returns

Return type: Unhydrated <TNode>