SchemaFactory Class
Creates various types of schema for TreeNodes.
This type is "sealed," meaning that code outside of the library defining it should not implement or extend it. Future versions of this type may add members or make typing of readonly members more specific.
Signature
/** @sealed */
export declare class SchemaFactory<out TScope extends string | undefined = string | undefined, TName extends number | string = string> extends SchemaFactory_base
Extends: SchemaFactory_base
Type Parameters
| Parameter | Constraint | Default | Description |
|---|---|---|---|
| TScope | string | undefined | string | undefined | Scope added as a prefix to the name of every schema produced by this factory. |
| TName | number | string | string | Type of names used to identify each schema produced in this factory. Typically this is just string but it is also possible to use string or number based enums if you prefer to identify your types that way. |
Remarks
For details related to inputting data constrained by schema (including via assignment), and how non-exact schema types are handled in general refer to Input. For information about recursive schema support, see methods postfixed with "recursive" and ValidateRecursiveSchema. To apply schema defined with this factory to a tree, see TreeViewConfiguration and viewWith(config). See the documentation on schema evolution for how to handle changes to schema over time.
All schema produced by this factory get a unique identifier by combining the scope with the schema's Name. The Name part may be explicitly provided as a parameter, or inferred as a structural combination of the provided types. The APIs which use this second approach, structural naming, also deduplicate all equivalent calls. Therefore two calls to array(allowedTypes) with the same allowedTypes will return the same TreeNodeSchema instance. On the other hand, two calls to array(name, allowedTypes) will always return different TreeNodeSchema instances and it is an error to use both in the same tree (since their identifiers are not unique).
For "customizable" schema (those which can be subclassed to customize them, see details below) some additional rules must be followed:
- Only a single schema can be used from the class hierarchy deriving from the base class produced by this factory. It is legal to subclass the returned class, and even subclass that class, but only a single class from that class hierarchy can ever be instantiated or passed to any API as a schema. These base classes can be used with
instanceof, but not with schema based APIs likeTree.is.
- If overriding the constructor, the constructor must accept the same argument as the base constructor
superand forward it tosuperunchanged.
- Properties for fields defined in the schema should not be overridden.
- Additional static members added to schema should pick relatively unique keys to reduce the risk of colliding with implementation details what are not exposed in the API.
- If exporting the schema from a package which uses API-Extractor, export the base class and derived class separately to work around a known limitation.
Note: POJO stands for Plain Old JavaScript Object. This means an object that works like a {} style object literal. In this case it means the prototype is Object.prototype and acts like a set of key value pairs (data, not methods). The usage below generalizes this to include array and map like objects as well.
There are two ways to use these APIs:
Customizable Approach:
- Declaration:
class X extends schemaFactory.object("x", {}) {}
- Allows adding "local" (non-persisted) members: additional members (including methods) can be added to the class.
- Prototype: The user-defined class.
- Structurally named Schema: Not Supported.
- Explicitly named Objects: Supported.
- Explicitly named Maps and Arrays: Supported: Both declaration approaches can be used.
- Node.js
assert.deepEqual: Compares like class instances: equal to other nodes of the same type with the same content, including custom local fields.
- IntelliSense: Shows and links to user-defined class by name:
X.
- Recursion: Supported with special declaration patterns.
POJO Emulation Approach:
- Declaration:
const X = schemaFactory.object("x", {}); type X = NodeFromSchema<typeof X>;
- Does not allow adding "local" (non-persisted) members: attempting to set non-field members will result in an error.
- Prototype:
Object.prototype,Map.prototype, orArray.prototypedepending on node kind.
- Structurally named Schema: Supported.
- Explicitly named Objects: Supported.
- Explicitly named Maps and Arrays: Not Supported.
- Node.js
assert.deepEqual: Compares like plain objects: equal to plain JavaScript objects with the same fields, and other nodes with the same fields, even if the types are different.
- IntelliSense: Shows internal type generation logic:
object & TreeNode & ObjectFromSchemaRecord<{}> & WithType<"test.x">.
- Recursion: Unsupported: Generated `.d.ts` files replace recursive references with `any`, breaking the use of recursive schema across compilation boundaries.
Note that while "POJO Emulation" nodes act a lot like POJO objects, they are not true POJO objects:
- Adding new arbitrary fields will error, as well some cases of invalid edits.
- They are implemented using proxies.
- They have state that is not exposed via enumerable own properties, including a TreeNodeSchema. This makes libraries like node.js
assert.deepEqualfail to detect differences in type.
- Assigning members has side effects (in this case editing the persisted/shared tree).
- Not all operations implied by the prototype will work correctly: stick to the APIs explicitly declared in the TypeScript types.
Constructors
| Constructor | Description |
|---|---|
| (constructor)(scope) | Construct a SchemaFactory with a given scope. |
Properties
| Property | Modifiers | Type | Description |
|---|---|---|---|
| identifier | readonly | FieldSchema<FieldKind.Identifier, typeof this.string> | A special readonly field which holds an identifier string for an object node. |
| scope | readonly | TScope | Prefix appended to the identifiers of all TreeNodeSchema produced by this builder. |
Methods
Constructor Details
(constructor)
Construct a SchemaFactory with a given scope.
Signature
constructor(
scope: TScope);
Remarks
There are no restrictions on mixing schemas from different schema factories. Typically each library will create one or more SchemaFactories and use them to define its schema.
Parameters
| Parameter | Type | Description |
|---|---|---|
| scope | TScope |
Property Details
identifier
A special readonly field which holds an identifier string for an object node.
Signature
get identifier(): FieldSchema<FieldKind.Identifier, typeof this.string>;
Type: FieldSchema<FieldKind.Identifier, typeof this.string>
Remarks
The value of this field, a "node identifier", is a string which identifies a node (or nodes) among all nodes in the tree. Node identifiers are strings, and can therefore be used as lookup keys in maps or written to a database. When the node is constructed, the identifier field does not need to be specified. When an identifier is not provided, the SharedTree will generate an identifier for the node automatically. The identifier generated by the SharedTree has the following properties:
- It is a UUID which will not collide with other generated UUIDs.
- It is compressed to a space-efficient representation when stored in the document. Reading the identifier before inserting the node into a tree prevents the identifier from being stored in its compressed form, resulting in a larger storage footprint.
- A compressed form of the identifier can be accessed at runtime via the Tree.shortId() API.
However, a user may alternatively supply their own string as the identifier if desired (for example, if importing identifiers from another system). In that case, if the user requires it to be unique, it is up to them to ensure uniqueness. User-supplied identifiers may be read immediately, even before insertion into the tree.
A node may have more than one identifier field (though note that this precludes the use of the Tree.shortId() API).
scope
Prefix appended to the identifiers of all TreeNodeSchema produced by this builder.
Signature
readonly scope: TScope;
Type: TScope
Remarks
Generally each independently developed library (possibly a package, but could also be part of a package or multiple packages developed together) should get its own unique scope. Then each schema in the library get a name which is unique within the library. The scope and name are joined (with a period) to form the schema identifier. Following this pattern allows a single application to depend on multiple libraries which define their own schema, and use them together in a single tree without risk of collisions. If a library logically contains sub-libraries with their own schema, they can be given a scope nested inside the parent scope, such as "ParentScope.ChildScope".
To avoid collisions between the scopes of libraries it is recommended that the libraries use Reverse domain name notation or a UUIDv4 for their scope. If this pattern is followed, application can safely use third party libraries without risk of the schema in them colliding.
You may opt out of using a scope by passing undefined, but note that this increases the risk of collisions.
Usage
Example 1
Fluid Framework follows this pattern, placing the schema for the built in leaf types in the com.fluidframework.leaf scope. If Fluid Framework publishes more schema in the future, they would be under some other com.fluidframework scope. This ensures that any schema defined by any other library will not conflict with Fluid Framework's schema as long as the library uses the recommended patterns for how to scope its schema..
Example 2
A library could generate a random UUIDv4, like 242c4397-49ed-47e6-8dd0-d5c3bc31778b and use that as the scope. Note: do not use this UUID: a new one must be randomly generated when needed to ensure collision resistance.
const factory = new SchemaFactory("242c4397-49ed-47e6-8dd0-d5c3bc31778b");
Method Details
array
Define a structurally typed TreeNodeSchema for a TreeArrayNode.
Signature
array<const T extends TreeNodeSchema | readonly TreeNodeSchema[]>(allowedTypes: T): TreeNodeSchemaNonClass<ScopedSchemaName<TScope, `Array<${string}>`>, NodeKind.Array, TreeArrayNode<T> & WithType<ScopedSchemaName<TScope, `Array<${string}>`>, NodeKind.Array>, Iterable<InsertableTreeNodeFromImplicitAllowedTypes<T>>, true, T, undefined>;
Type Parameters
| Parameter | Constraint | Description |
|---|---|---|
| T | TreeNodeSchema | readonly TreeNodeSchema[] |
Remarks
The identifier for this Array is defined as a function of the provided types. It is still scoped to this SchemaFactory, but multiple calls with the same arguments will return the same schema object, providing somewhat structural typing. This does not support recursive types.
If using these structurally named arrays, other types in this schema builder should avoid names of the form Array<${string}>.
Example
The returned schema should be used as a schema directly:
const MyArray = factory.array(factory.number);
type MyArray = NodeFromSchema<typeof MyArray>;
Or inline:
factory.object("Foo", {myArray: factory.array(factory.number)});
Parameters
| Parameter | Type | Description |
|---|---|---|
| allowedTypes | T | The types that may appear in the array. |
Returns
Return type: TreeNodeSchemaNonClass<ScopedSchemaName<TScope, `Array<${string}>`>, NodeKind.Array, TreeArrayNode<T> & WithType<ScopedSchemaName<TScope, `Array<${string}>`>, NodeKind.Array>, Iterable<InsertableTreeNodeFromImplicitAllowedTypes<T>>, true, T, undefined>
array
Define a TreeNodeSchemaClass for a TreeArrayNode.
Signature
array<const Name extends TName, const T extends ImplicitAllowedTypes>(name: Name, allowedTypes: T): TreeNodeSchemaClass<ScopedSchemaName<TScope, Name>, NodeKind.Array, TreeArrayNode<T> & WithType<ScopedSchemaName<TScope, Name>, NodeKind.Array>, Iterable<InsertableTreeNodeFromImplicitAllowedTypes<T>>, true, T, undefined>;
Type Parameters
| Parameter | Constraint | Description |
|---|---|---|
| Name | TName | |
| T | ImplicitAllowedTypes |
Example
class NamedArray extends factory.array("name", factory.number) {}
Parameters
| Parameter | Type | Description |
|---|---|---|
| name | Name | Unique identifier for this schema within this factory's scope. |
| allowedTypes | T | The types that may appear in the array. |
Returns
Return type: TreeNodeSchemaClass<ScopedSchemaName<TScope, Name>, NodeKind.Array, TreeArrayNode<T> & WithType<ScopedSchemaName<TScope, Name>, NodeKind.Array>, Iterable<InsertableTreeNodeFromImplicitAllowedTypes<T>>, true, T, undefined>
arrayRecursive
SchemaFactory.array except tweaked to work better for recursive types. Use with ValidateRecursiveSchema for improved type safety.
Signature
arrayRecursive<const Name extends TName, const T extends System_Unsafe.ImplicitAllowedTypesUnsafe>(name: Name, allowedTypes: T): TreeNodeSchemaClass<ScopedSchemaName<TScope, Name>, NodeKind.Array, System_Unsafe.TreeArrayNodeUnsafe<T> & WithType<ScopedSchemaName<TScope, Name>, NodeKind.Array, unknown>, {
[Symbol.iterator](): Iterator<System_Unsafe.InsertableTreeNodeFromImplicitAllowedTypesUnsafe<T>>;
}, false, T, undefined>;
Type Parameters
| Parameter | Constraint | Description |
|---|---|---|
| Name | TName | |
| T | System_Unsafe.ImplicitAllowedTypesUnsafe |
Remarks
This version of SchemaFactory.array uses the same workarounds as objectRecursive(name, t). See ValidateRecursiveSchema for additional information about using recursive schema. See also FixRecursiveArraySchema for additional information specific to recursive arrays schema exports.
Parameters
| Parameter | Type | Description |
|---|---|---|
| name | Name | |
| allowedTypes | T |
Returns
Return type: TreeNodeSchemaClass<ScopedSchemaName<TScope, Name>, NodeKind.Array, System_Unsafe.TreeArrayNodeUnsafe<T> & WithType<ScopedSchemaName<TScope, Name>, NodeKind.Array, unknown>, { [Symbol.iterator](): Iterator<System_Unsafe.InsertableTreeNodeFromImplicitAllowedTypesUnsafe<T>>; }, false, T, undefined>
getStructuralType
Retrieves or creates a structural TreeNodeSchema with the specified name and types.
Signature
protected getStructuralType(fullName: string, types: TreeNodeSchema | readonly TreeNodeSchema[], builder: () => TreeNodeSchema): TreeNodeSchema;
Parameters
| Parameter | Type | Description |
|---|---|---|
| fullName | string | The name for the structural schema. |
| types | TreeNodeSchema | readonly TreeNodeSchema[] | The input schema(s) used to define the structural schema. |
| builder | () => TreeNodeSchema | A function that builds the schema if it does not already exist. |
Returns
The structural TreeNodeSchema associated with the given name and types.
Return type: TreeNodeSchema
Error Handling
UsageError if a schema structurally named schema with the same name is cached in structuralTypes but had different input types.
map
Define a structurally typed TreeNodeSchema for a TreeMapNode.
Signature
map<const T extends TreeNodeSchema | readonly TreeNodeSchema[]>(allowedTypes: T): TreeNodeSchemaNonClass<ScopedSchemaName<TScope, `Map<${string}>`>, NodeKind.Map, TreeMapNode<T> & WithType<ScopedSchemaName<TScope, `Map<${string}>`>, NodeKind.Map>, MapNodeInsertableData<T>, true, T, undefined>;
Type Parameters
| Parameter | Constraint | Description |
|---|---|---|
| T | TreeNodeSchema | readonly TreeNodeSchema[] |
Remarks
The unique identifier for this Map is defined as a function of the provided types. It is still scoped to this SchemaBuilder, but multiple calls with the same arguments will return the same schema object, providing somewhat structural typing. This does not support recursive types.
If using these structurally named maps, other types in this schema builder should avoid names of the form Map<${string}>.
Example
The returned schema should be used as a schema directly:
const MyMap = factory.map(factory.number);
type MyMap = NodeFromSchema<typeof MyMap>;
Or inline:
factory.object("Foo", {myMap: factory.map(factory.number)});
Parameters
| Parameter | Type | Description |
|---|---|---|
| allowedTypes | T | The types that may appear as values in the map. |
Returns
Return type: TreeNodeSchemaNonClass<ScopedSchemaName<TScope, `Map<${string}>`>, NodeKind.Map, TreeMapNode<T> & WithType<ScopedSchemaName<TScope, `Map<${string}>`>, NodeKind.Map>, MapNodeInsertableData<T>, true, T, undefined>
map
Define a TreeNodeSchema for a TreeMapNode.
Signature
map<Name extends TName, const T extends ImplicitAllowedTypes>(name: Name, allowedTypes: T): TreeNodeSchemaClass<ScopedSchemaName<TScope, Name>, NodeKind.Map, TreeMapNode<T> & WithType<ScopedSchemaName<TScope, Name>, NodeKind.Map>, MapNodeInsertableData<T>, true, T, undefined>;
Type Parameters
| Parameter | Constraint | Description |
|---|---|---|
| Name | TName | |
| T | ImplicitAllowedTypes |
Example
class NamedMap extends factory.map("name", factory.number) {}
Parameters
| Parameter | Type | Description |
|---|---|---|
| name | Name | Unique identifier for this schema within this factory's scope. |
| allowedTypes | T | The types that may appear as values in the map. |
Returns
Return type: TreeNodeSchemaClass<ScopedSchemaName<TScope, Name>, NodeKind.Map, TreeMapNode<T> & WithType<ScopedSchemaName<TScope, Name>, NodeKind.Map>, MapNodeInsertableData<T>, true, T, undefined>
mapRecursive
SchemaFactory.map except tweaked to work better for recursive types. Use with ValidateRecursiveSchema for improved type safety.
Signature
mapRecursive<Name extends TName, const T extends System_Unsafe.ImplicitAllowedTypesUnsafe>(name: Name, allowedTypes: T): TreeNodeSchemaClass<ScopedSchemaName<TScope, Name>, NodeKind.Map, System_Unsafe.TreeMapNodeUnsafe<T> & WithType<ScopedSchemaName<TScope, Name>, NodeKind.Map, unknown>, {
[Symbol.iterator](): Iterator<[
string,
System_Unsafe.InsertableTreeNodeFromImplicitAllowedTypesUnsafe<T>
]>;
} | {
readonly [x: string]: System_Unsafe.InsertableTreeNodeFromImplicitAllowedTypesUnsafe<T>;
}, false, T, undefined>;
Type Parameters
| Parameter | Constraint | Description |
|---|---|---|
| Name | TName | |
| T | System_Unsafe.ImplicitAllowedTypesUnsafe |
Remarks
This version of SchemaFactory.map uses the same workarounds as objectRecursive(name, t). See ValidateRecursiveSchema for additional information about using recursive schema.
Parameters
| Parameter | Type | Description |
|---|---|---|
| name | Name | |
| allowedTypes | T |
Returns
Return type: TreeNodeSchemaClass<ScopedSchemaName<TScope, Name>, NodeKind.Map, System_Unsafe.TreeMapNodeUnsafe<T> & WithType<ScopedSchemaName<TScope, Name>, NodeKind.Map, unknown>, { [Symbol.iterator](): Iterator<[ string, System_Unsafe.InsertableTreeNodeFromImplicitAllowedTypesUnsafe<T> ]>; } | { readonly [x: string]: System_Unsafe.InsertableTreeNodeFromImplicitAllowedTypesUnsafe<T>; }, false, T, undefined>
object
Define a TreeNodeSchemaClass for a TreeObjectNode.
Signature
object<const Name extends TName, const T extends RestrictiveStringRecord<ImplicitFieldSchema>>(name: Name, fields: T): TreeNodeSchemaClass<ScopedSchemaName<TScope, Name>, NodeKind.Object, TreeObjectNode<T, ScopedSchemaName<TScope, Name>>, object & InsertableObjectFromSchemaRecord<T>, true, T>;
Type Parameters
| Parameter | Constraint | Description |
|---|---|---|
| Name | TName | |
| T | RestrictiveStringRecord<ImplicitFieldSchema> |
Parameters
| Parameter | Type | Description |
|---|---|---|
| name | Name | Unique identifier for this schema within this factory's scope. |
| fields | T | Schema for fields of the object node's schema. Defines what children can be placed under each key. |
Returns
Return type: TreeNodeSchemaClass<ScopedSchemaName<TScope, Name>, NodeKind.Object, TreeObjectNode<T, ScopedSchemaName<TScope, Name>>, object & InsertableObjectFromSchemaRecord<T>, true, T>
objectRecursive
object(name, fields) except tweaked to work better for recursive types. Use with ValidateRecursiveSchema for improved type safety.
Signature
objectRecursive<const Name extends TName, const T extends RestrictiveStringRecord<System_Unsafe.ImplicitFieldSchemaUnsafe>>(name: Name, t: T): TreeNodeSchemaClass<ScopedSchemaName<TScope, Name>, NodeKind.Object, System_Unsafe.TreeObjectNodeUnsafe<T, ScopedSchemaName<TScope, Name>>, object & System_Unsafe.InsertableObjectFromSchemaRecordUnsafe<T>, false, T>;
Type Parameters
| Parameter | Constraint | Description |
|---|---|---|
| Name | TName | |
| T | RestrictiveStringRecord<System_Unsafe.ImplicitFieldSchemaUnsafe> |
Remarks
This version of object(name, fields) has fewer type constraints to work around TypeScript limitations, see Unenforced. See ValidateRecursiveSchema for additional information about using recursive schema.
Additionally ImplicitlyConstructable is disabled (forcing use of constructor) to avoid error TS2589: Type instantiation is excessively deep and possibly infinite. which otherwise gets reported at sometimes incorrect source locations that vary based on incremental builds.
Parameters
| Parameter | Type | Description |
|---|---|---|
| name | Name | |
| t | T |
Returns
Return type: TreeNodeSchemaClass<ScopedSchemaName<TScope, Name>, NodeKind.Object, System_Unsafe.TreeObjectNodeUnsafe<T, ScopedSchemaName<TScope, Name>>, object & System_Unsafe.InsertableObjectFromSchemaRecordUnsafe<T>, false, T>