---
lang: en
title: 'API docs: context.inject.binding'
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.inject.binding.html
---

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[Home](./index.md) &gt; [@loopback/context](./context.md) &gt; [inject](./context.inject.md) &gt; [binding](./context.inject.binding.md)

## inject.binding() function

Inject the binding object for the given key. This is useful if a binding needs to be set up beyond just a constant value allowed by `@inject.setter`<!-- -->. The injected binding is found or created based on the `metadata.bindingCreation` option. See `BindingCreationPolicy` for more details.

**Signature:**

```typescript
binding: (bindingKey?: string | BindingKey<unknown>, metadata?: InjectBindingMetadata) => (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">

bindingKey


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

string \| [BindingKey](./context.bindingkey.md)<!-- -->&lt;unknown&gt;


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

_(Optional)_ Binding key


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

metadata


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

[InjectBindingMetadata](./context.injectbindingmetadata.md)


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

_(Optional)_ Metadata for the injection


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

**Returns:**

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

## Example


```ts
class MyAuthAction {
  @inject.binding('current-user', {
    bindingCreation: BindingCreationPolicy.ALWAYS_CREATE,
  })
  private userBinding: Binding<UserProfile>;

  async authenticate() {
    this.userBinding.toDynamicValue(() => {...});
  }
}
```