@fluidframework/map

@fluidframework/map

SharedMap

The SharedMap distributed data structure can be used to store key-value pairs. It provides the same API for setting and retrieving values that JavaScript developers are accustomed to with the Map built-in object.

Creation

To create a SharedMap, call the static create method:

const myMap = SharedMap.create(this.runtime, id);

Usage

Unlike the JavaScript Map, a SharedMap's keys must be strings. The value must only be plain JS objects or handles (e.g. to another DDS or Fluid objects).

In collaborative scenarios, the value is settled with a policy of last write wins.

.wait()

SharedMap has a wait method in addition to the normal get, which returns a Promise that resolves to the value when the key becomes available.

Eventing

SharedMap 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 or delete, and provide the key and previous value that was stored at that key. clear will be emitted in response to a clear.

SharedDirectory and IDirectory

A SharedDirectory is a map-like DDS that additionally supports storing key/value pairs within a tree of subdirectories. This subdirectory tree can be used to give hierarchical structure to stored key/value pairs rather than storing them on a flat map. Both the SharedDirectory and any subdirectories are IDirectories.

Creation

To create a SharedDirectory, call the static create method:

const myDirectory = SharedDirectory.create(this.runtime, id);

Usage

The map operations on an IDirectory refer to the key/value pairs stored in that IDirectory, and function just like SharedMap including the same extra functionality and restrictions on keys and values. To operate on the subdirectory structure, use the corresponding subdirectory methods.

getWorkingDirectory()

To "navigate" the subdirectory structure, IDirectory provides a getWorkingDirectory method which takes a relative path and returns the IDirectory located at that path if it exists.

Eventing

valueChanged events additionally provide the absolute path to the subdirectory storing the value that changed.

dispose events are fired on sub directory which is deleted. Any access to this sub directory will throw an error once it is disposed.