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

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[Home](./index.md) &gt; [@loopback/metadata](./metadata.md)

## metadata package

A package with utilities to help developers implement [TypeScript decorators](https://www.typescriptlang.org/docs/handbook/decorators.html)<!-- -->, define/merge metadata, and inspect metadata.

## Remarks

Utilities:

- Reflector: Wrapper of [reflect-metadata](https://github.com/rbuckton/reflect-metadata)<!-- -->. - Decorator factories: A set of factories for class/method/property/parameter decorators to apply metadata to a given class and its static or instance members. - MetadataInspector: High level APIs to inspect a class and/or its members to get metadata applied by decorators.

## Classes

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

Class


</th><th>

Description


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

[ClassDecoratorFactory](./metadata.classdecoratorfactory.md)


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

Factory for class decorators


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

[DecoratorFactory](./metadata.decoratorfactory.md)


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

Base factory class for decorator functions


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

[MetadataAccessor](./metadata.metadataaccessor.md)


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

A strongly-typed metadata accessor via reflection


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

[MetadataInspector](./metadata.metadatainspector.md)


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

Inspector for metadata applied by decorators


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

[MethodDecoratorFactory](./metadata.methoddecoratorfactory.md)


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

Factory for method decorators


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

[MethodMultiDecoratorFactory](./metadata.methodmultidecoratorfactory.md)


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

Factory for an append-array of method-level decorators The `@response` metadata for a method is an array. Each item in the array should be a single value, containing a response code and a single spec or Model. This should allow:


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

[MethodParameterDecoratorFactory](./metadata.methodparameterdecoratorfactory.md)


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

Factory for method level parameter decorator.


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

[NamespacedReflect](./metadata.namespacedreflect.md)


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


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

[ParameterDecoratorFactory](./metadata.parameterdecoratorfactory.md)


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

Factory for parameter decorators


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

[PropertyDecoratorFactory](./metadata.propertydecoratorfactory.md)


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

Factory for property decorators


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

## Interfaces

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

Interface


</th><th>

Description


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

[DecoratorOptions](./metadata.decoratoroptions.md)


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

Options for a decorator


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

[DesignTimeMethodMetadata](./metadata.designtimemethodmetadata.md)


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

Design time metadata for a method.


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

[InspectionOptions](./metadata.inspectionoptions.md)


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

Options for inspection


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

[MetadataMap](./metadata.metadatamap.md)


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

An object mapping keys to corresponding metadata


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

## Variables

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

Variable


</th><th>

Description


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

[Reflector](./metadata.reflector.md)


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


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

## Type Aliases

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

Type Alias


</th><th>

Description


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

[DecoratorType](./metadata.decoratortype.md)


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

Decorator function types


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

[MetadataKey](./metadata.metadatakey.md)


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

Key for metadata access via reflection


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