@a11d/metadata/dist/createMetadataDecorator.js

A set of behavior-less metadata decorators.

/**
 * Creates a metadata decorator with the given key supporting both class and property metadata.
 * It also provides a getter for retrieving metadata by key and key-path (e.g. 'property.subProperty').
 * The key-path getter needs the property to be decorated with `@type(SubPropertyType)`
 * for the generated decorator to be able to resolve the metadata.
 */
export function createMetadataDecorator(key) {
    function metadata(value) {
        return (target, propertyKey) => {
            Reflect.defineMetadata(key, value, target, propertyKey);
        };
    }
    metadata.get = function (constructor, propertyKey) {
        return propertyKey === undefined
            ? Reflect.getMetadata(key, constructor)
            : Reflect.getMetadata(key, constructor.prototype, propertyKey);
    };
    metadata.getByKeyPath = function (constructor, keyPath) {
        const keys = keyPath.split('.');
        const key = keys.pop();
        const parent = keys.reduce((previousType, key) => type.get(previousType, key), constructor);
        if (!parent) {
            return undefined;
        }
        return metadata.get(parent, key);
    };
    return metadata;
}