@loopback/docs/site/apidocs/core.lifecycleobserverregistry.invokeobserver.md

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---
lang: en
title: 'API docs: core.lifecycleobserverregistry.invokeobserver'
keywords: LoopBack 4.0, LoopBack 4, Node.js, TypeScript, OpenAPI
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[Home](./index.md) &gt; [@loopback/core](./core.md) &gt; [LifeCycleObserverRegistry](./core.lifecycleobserverregistry.md) &gt; [invokeObserver](./core.lifecycleobserverregistry.invokeobserver.md)

## LifeCycleObserverRegistry.invokeObserver() method

Invoke an observer for the given event

**Signature:**

```typescript
protected invokeObserver(observer: LifeCycleObserver, event: keyof LifeCycleObserver): Promise<void>;
```

## Parameters

<table><thead><tr><th>

Parameter


</th><th>

Type


</th><th>

Description


</th></tr></thead>
<tbody><tr><td markdown="1">

observer


</td><td markdown="1">

[LifeCycleObserver](./core.lifecycleobserver.md)


</td><td markdown="1">

A life cycle observer


</td></tr>
<tr><td markdown="1">

event


</td><td markdown="1">

keyof [LifeCycleObserver](./core.lifecycleobserver.md)


</td><td markdown="1">

Event name


</td></tr>
</tbody></table>

**Returns:**

Promise&lt;void&gt;