@loopback/docs

--- 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 ---  [Home](./index.md) > [@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>