@loopback/docs/site/apidocs/core.extensions.view.md

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---
lang: en
title: 'API docs: core.extensions.view'
keywords: LoopBack 4.0, LoopBack 4, Node.js, TypeScript, OpenAPI
sidebar: lb4_sidebar
editurl: https://github.com/loopbackio/loopback-next/tree/master/packages/core
permalink: /doc/en/lb4/apidocs.core.extensions.view.html
---

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[Home](./index.md) &gt; [@loopback/core](./core.md) &gt; [extensions](./core.extensions.md) &gt; [view](./core.extensions.view.md)

## extensions.view() function

Inject a `ContextView` for extensions of the extension point. The view can then be listened on events such as `bind`<!-- -->, `unbind`<!-- -->, or `refresh` to react on changes of extensions.

**Signature:**

```typescript
function view(extensionPointName?: string, metadata?: InjectionMetadata): (target: Object, member: string | undefined, methodDescriptorOrParameterIndex?: number | TypedPropertyDescriptor<any> | undefined) => void;
```

## Parameters

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

Parameter


</th><th>

Type


</th><th>

Description


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

extensionPointName


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

string


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

_(Optional)_ Name of the extension point. If not supplied, we use the `name` tag from the extension point binding or the class name of the extension point class. If a class needs to inject extensions from multiple extension points, use different `extensionPointName` for different types of extensions.


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

metadata


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

[InjectionMetadata](./context.injectionmetadata.md)


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

_(Optional)_ Optional injection metadata


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

**Returns:**

(target: Object, member: string \| undefined, methodDescriptorOrParameterIndex?: number \| TypedPropertyDescriptor&lt;any&gt; \| undefined) =&gt; void

## Example


```ts
import {extensionPoint, extensions} from '@loopback/core';

@extensionPoint(GREETER_EXTENSION_POINT_NAME)
export class GreetingService {
 constructor(
   @extensions.view() // Inject a context view for extensions of the extension point
   private greetersView: ContextView<Greeter>,
   // ...
) {
  // ...
}
```