@loopback/docs

--- lang: en title: 'API docs: context.contextsubscriptionmanager' keywords: LoopBack 4.0, LoopBack 4, Node.js, TypeScript, OpenAPI sidebar: lb4_sidebar editurl: https://github.com/loopbackio/loopback-next/tree/master/packages/context permalink: /doc/en/lb4/apidocs.context.contextsubscriptionmanager.html ---  [Home](./index.md) > [@loopback/context](./context.md) > [ContextSubscriptionManager](./context.contextsubscriptionmanager.md) ## ContextSubscriptionManager class Manager for context observer subscriptions **Signature:** ```typescript export declare class ContextSubscriptionManager extends EventEmitter ``` **Extends:** EventEmitter ## Constructors <table><thead><tr><th> Constructor </th><th> Modifiers </th><th> Description </th></tr></thead> <tbody><tr><td markdown="1"> [(constructor)(context)](./context.contextsubscriptionmanager._constructor_.md) </td><td markdown="1"> </td><td markdown="1"> Constructs a new instance of the `ContextSubscriptionManager` class </td></tr> </tbody></table> ## Properties <table><thead><tr><th> Property </th><th> Modifiers </th><th> Type </th><th> Description </th></tr></thead> <tbody><tr><td markdown="1"> [\_observers](./context.contextsubscriptionmanager._observers.md) </td><td markdown="1"> `protected` </td><td markdown="1"> Set<[ContextEventObserver](./context.contexteventobserver.md)> \| undefined </td><td markdown="1"> A list of registered context observers. The Set will be created when the first observer is added. </td></tr> <tr><td markdown="1"> [\_parentContextEventListener?](./context.contextsubscriptionmanager._parentcontexteventlistener.md) </td><td markdown="1"> `protected` </td><td markdown="1"> [ContextEventListener](./context.contexteventlistener.md) </td><td markdown="1"> _(Optional)_ A listener to watch parent context events </td></tr> <tr><td markdown="1"> [context](./context.contextsubscriptionmanager.context.md) </td><td markdown="1"> `protected` `readonly` </td><td markdown="1"> [Context](./context.context.md) </td><td markdown="1"> </td></tr> </tbody></table> ## Methods <table><thead><tr><th> Method </th><th> Modifiers </th><th> Description </th></tr></thead> <tbody><tr><td markdown="1"> [close()](./context.contextsubscriptionmanager.close.md) </td><td markdown="1"> </td><td markdown="1"> Close the context: clear observers, stop notifications, and remove event listeners from its parent context. </td></tr> <tr><td markdown="1"> [isSubscribed(observer)](./context.contextsubscriptionmanager.issubscribed.md) </td><td markdown="1"> </td><td markdown="1"> Check if an observer is subscribed to this context </td></tr> <tr><td markdown="1"> [notifyObservers(event, observers)](./context.contextsubscriptionmanager.notifyobservers.md) </td><td markdown="1"> `protected` </td><td markdown="1"> Publish an event to the registered observers. Please note the notification is queued and performed asynchronously so that we allow fluent APIs such as `ctx.bind('key').to(...).tag(...);` and give observers the fully populated binding. </td></tr> <tr><td markdown="1"> [subscribe(observer)](./context.contextsubscriptionmanager.subscribe.md) </td><td markdown="1"> </td><td markdown="1"> Add a context event observer to the context </td></tr> <tr><td markdown="1"> [unsubscribe(observer)](./context.contextsubscriptionmanager.unsubscribe.md) </td><td markdown="1"> </td><td markdown="1"> Remove the context event observer from the context </td></tr> <tr><td markdown="1"> [waitUntilPendingNotificationsDone(timeout)](./context.contextsubscriptionmanager.waituntilpendingnotificationsdone.md) </td><td markdown="1"> </td><td markdown="1"> Wait until observers are notified for all of currently pending notification events. This method is for test only to perform assertions after observers are notified for relevant events. </td></tr> </tbody></table>