@loopback/docs

--- lang: en title: 'API docs: metadata.decoratorfactory' 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.decoratorfactory.html ---  [Home](./index.md) > [@loopback/metadata](./metadata.md) > [DecoratorFactory](./metadata.decoratorfactory.md) ## DecoratorFactory class Base factory class for decorator functions **Signature:** ```typescript export declare class DecoratorFactory<T, // Type of the metadata spec for individual class/method/property/parameter M extends T | MetadataMap<T> | MetadataMap<T[]>, // Type of the metadata D extends DecoratorType> ``` ## Example ``` function classDecorator(spec: MySpec): ClassDecorator { return ClassDecoratorFactory.createDecorator('my-key', spec); } ``` or ``` function classDecorator(spec: MySpec): ClassDecorator { const factory: ClassDecoratorFactory<MySpec>('my-key', spec); return factory.create(); } ``` These functions above declare `@classDecorator` that can be used as follows: ``` @classDecorator({x: 1}) class MyController {} ``` ## Constructors <table><thead><tr><th> Constructor </th><th> Modifiers </th><th> Description </th></tr></thead> <tbody><tr><td markdown="1"> [(constructor)(key, spec, options)](./metadata.decoratorfactory._constructor_.md) </td><td markdown="1"> </td><td markdown="1"> Construct a new class decorator factory </td></tr> </tbody></table> ## Properties <table><thead><tr><th> Property </th><th> Modifiers </th><th> Type </th><th> Description </th></tr></thead> <tbody><tr><td markdown="1"> [decoratorName](./metadata.decoratorfactory.decoratorname.md) </td><td markdown="1"> `protected` </td><td markdown="1"> string </td><td markdown="1"> </td></tr> <tr><td markdown="1"> [key](./metadata.decoratorfactory.key.md) </td><td markdown="1"> `protected` </td><td markdown="1"> string </td><td markdown="1"> </td></tr> <tr><td markdown="1"> [options](./metadata.decoratorfactory.options.md) </td><td markdown="1"> `protected` </td><td markdown="1"> [DecoratorOptions](./metadata.decoratoroptions.md) </td><td markdown="1"> </td></tr> <tr><td markdown="1"> [spec](./metadata.decoratorfactory.spec.md) </td><td markdown="1"> `protected` </td><td markdown="1"> T </td><td markdown="1"> </td></tr> <tr><td markdown="1"> [TARGET](./metadata.decoratorfactory.target.md) </td><td markdown="1"> `static` </td><td markdown="1"> string </td><td markdown="1"> A constant to reference the target of a decoration </td></tr> </tbody></table> ## Methods <table><thead><tr><th> Method </th><th> Modifiers </th><th> Description </th></tr></thead> <tbody><tr><td markdown="1"> [\_createDecorator(key, spec, options)](./metadata.decoratorfactory._createdecorator.md) </td><td markdown="1"> `protected` `static` </td><td markdown="1"> Create a decorator function </td></tr> <tr><td markdown="1"> [allowInheritance()](./metadata.decoratorfactory.allowinheritance.md) </td><td markdown="1"> `protected` </td><td markdown="1"> </td></tr> <tr><td markdown="1"> [cloneDeep(val)](./metadata.decoratorfactory.clonedeep.md) </td><td markdown="1"> `static` </td><td markdown="1"> </td></tr> <tr><td markdown="1"> [create()](./metadata.decoratorfactory.create.md) </td><td markdown="1"> </td><td markdown="1"> Create a decorator function of the given type. Each sub class MUST implement this method. </td></tr> <tr><td markdown="1"> [decorate(target, member, descriptorOrIndex)](./metadata.decoratorfactory.decorate.md) </td><td markdown="1"> `protected` </td><td markdown="1"> Base implementation of the decorator function </td></tr> <tr><td markdown="1"> [duplicateDecorationError(target, member, descriptorOrIndex)](./metadata.decoratorfactory.duplicatedecorationerror.md) </td><td markdown="1"> `protected` </td><td markdown="1"> Create an error to report if the decorator is applied to the target more than once </td></tr> <tr><td markdown="1"> [getNumberOfParameters(target, member)](./metadata.decoratorfactory.getnumberofparameters.md) </td><td markdown="1"> `static` </td><td markdown="1"> Get the number of parameters for a given constructor or method </td></tr> <tr><td markdown="1"> [getTarget(spec)](./metadata.decoratorfactory.gettarget.md) </td><td markdown="1"> </td><td markdown="1"> Get the optional decoration target of a given spec </td></tr> <tr><td markdown="1"> [getTargetName(target, member, descriptorOrIndex)](./metadata.decoratorfactory.gettargetname.md) </td><td markdown="1"> `static` </td><td markdown="1"> Get the qualified name of a decoration target. </td></tr> <tr><td markdown="1"> [inherit(inheritedMetadata)](./metadata.decoratorfactory.inherit.md) </td><td markdown="1"> `protected` </td><td markdown="1"> Inherit metadata from base classes. By default, this method merges base metadata into the spec if `allowInheritance` is set to `true`. To customize the behavior, this method can be overridden by sub classes. </td></tr> <tr><td markdown="1"> [mergeWithInherited(inheritedMetadata, target, member, descriptorOrIndex)](./metadata.decoratorfactory.mergewithinherited.md) </td><td markdown="1"> `protected` </td><td markdown="1"> This method is called by the default implementation of the decorator function to merge the spec argument from the decoration with the inherited metadata for a class, all properties, all methods, or all method parameters that are decorated by this decorator. It MUST be overridden by subclasses to process inherited metadata. </td></tr> <tr><td markdown="1"> [mergeWithOwn(ownMetadata, target, member, descriptorOrIndex)](./metadata.decoratorfactory.mergewithown.md) </td><td markdown="1"> `protected` </td><td markdown="1"> This method is called by the default implementation of the decorator function to merge the spec argument from the decoration with the own metadata for a class, all properties, all methods, or all method parameters that are decorated by this decorator. It MUST be overridden by subclasses to process own metadata. </td></tr> <tr><td markdown="1"> [withTarget(spec, target)](./metadata.decoratorfactory.withtarget.md) </td><td markdown="1"> </td><td markdown="1"> Set a reference to the target class or prototype for a given spec if it's an object </td></tr> </tbody></table>