SharedCell Class

The SharedCell distributed data structure can be used to store a single serializable value.

Signature

export declare class SharedCell<T = any> extends SharedObject<ISharedCellEvents<T>> implements ISharedCell<T>

Extends: SharedObject<ISharedCellEvents

Implements: ISharedCell

Type Parameters

Parameter	Default	Description
T	any

Remarks

### Creation

To create a SharedCell, call the static create method:

const myCell = SharedCell.create(this.runtime, id);

### Usage

The value stored in the cell can be set with the .set() method and retrieved with the .get() method:

myCell.set(3);
console.log(myCell.get()); // 3

The value must only be plain JS objects or SharedObject handles (e.g. to another DDS or Fluid object). In collaborative scenarios, the value is settled with a policy of _last write wins_.

The .delete() method will delete the stored value from the cell:

myCell.delete();
console.log(myCell.get()); // undefined

The .empty() method will check if the value is undefined.

if (myCell.empty()) {
  // myCell.get() will return undefined
} else {
  // myCell.get() will return a non-undefined value
}

### Eventing

SharedCell is an EventEmitter, and will emit events when other clients make modifications. You should register for these events and respond appropriately as the data is modified. valueChanged will be emitted in response to a set, and delete will be emitted in response to a delete.

Constructors

Constructor	Description
(constructor)(id, runtime, attributes)	Constructs a new shared cell. If the object is non-local an id and service interfaces will be provided

Static Methods

Method	Return Type	Description
create(runtime, id)	SharedCell<any>	Create a new shared cell
getFactory()	IChannelFactory	Get a factory for SharedCell to register with the data store.

Methods

Method	Return Type	Description
delete()	void	Delete the value from the cell.
empty()	boolean	Checks whether cell is empty or not.
get()	Serializable<T> | undefined	Retrieves the cell value.
initializeLocalCore()	void	Initialize a local instance of cell
loadCore(storage)	Promise<void>
onDisconnect()	void	Call back on disconnect
processCore(message, local, localOpMetadata)	void	Process a cell operation
set(value)	void	Sets the cell value.
summarizeCore(serializer)	ISummaryTreeWithStats	Create a summary for the cell

Constructor Details

(constructor)

Constructs a new shared cell. If the object is non-local an id and service interfaces will be provided

Signature

constructor(id: string, runtime: IFluidDataStoreRuntime, attributes: IChannelAttributes);

Parameters

Parameter	Type	Description
id	string	optional name of the shared map
runtime	IFluidDataStoreRuntime	data store runtime the shared map belongs to
attributes	IChannelAttributes

Method Details

create

Create a new shared cell

Signature

static create(runtime: IFluidDataStoreRuntime, id?: string): SharedCell<any>;

Parameters

Parameter	Modifiers	Type	Description
runtime		IFluidDataStoreRuntime	data store runtime the new shared map belongs to
id	optional	string	optional name of the shared map

Returns

newly create shared map (but not attached yet)

Return type: SharedCell<any>

delete

Delete the value from the cell.

Signature

delete(): void;

empty

Checks whether cell is empty or not.

Signature

empty(): boolean;

Returns

• true if the value of cell is undefined, false otherwise

Return type: boolean

get

Retrieves the cell value.

Signature

get(): Serializable<T> | undefined;

Returns

• the value of the cell

Return type: Serializable<T> | undefined

getFactory

Get a factory for SharedCell to register with the data store.

Signature

static getFactory(): IChannelFactory;

Returns

a factory that creates and load SharedCell

Return type: IChannelFactory

initializeLocalCore

Initialize a local instance of cell

Signature

protected initializeLocalCore(): void;

loadCore

Signature

protected loadCore(storage: IChannelStorageService): Promise<void>;

Parameters

Parameter	Type	Description
storage	IChannelStorageService

Returns

Return type: Promise<void>

onDisconnect

Call back on disconnect

Signature

protected onDisconnect(): void;

processCore

Process a cell operation

Signature

protected processCore(message: ISequencedDocumentMessage, local: boolean, localOpMetadata: unknown): void;

Parameters

Parameter	Type	Description
message	ISequencedDocumentMessage	the message to prepare
local	boolean	whether the message was sent by the local client
localOpMetadata	unknown	For local client messages, this is the metadata that was submitted with the message. For messages from a remote client, this will be undefined.

set

Sets the cell value.

Signature

set(value: Serializable<T>): void;

Parameters

Parameter	Type	Description
value	Serializable<T>	a JSON-able or SharedObject value to set the cell to

summarizeCore

Create a summary for the cell

Signature

protected summarizeCore(serializer: IFluidSerializer): ISummaryTreeWithStats;

Parameters

Parameter	Type	Description
serializer	IFluidSerializer

Returns

the summary of the current state of the cell

Return type: ISummaryTreeWithStats