@nestjs/common/utils/extend-metadata.util.js

Decorators, pipes, exceptions and utilities for NestJS applications: @Controller(), @Injectable(), @Body(), ValidationPipe, HttpException and more.

export function extendArrayMetadata(key, metadata, target) {
    const previousValue = Reflect.getMetadata(key, target) || [];
    const value = [...previousValue, ...metadata];
    Reflect.defineMetadata(key, value, target);
}
/**
 * Reads the args a param decorator at `index` adds to. An overriding method
 * starts from its parent's args, so the entry inherited at `index` is left out
 * and the override's decorator replaces it.
 *
 * @internal
 */
export function getParamArgsMetadata(metadataKey, target, key, index) {
    const args = Reflect.getMetadata(metadataKey, target.constructor, key) || {};
    const inherited = Reflect.getMetadata(metadataKey, Object.getPrototypeOf(target.constructor), key) || {};
    // `assignMetadata` and `assignCustomParameterMetadata` spread shallowly, so
    // an entry the override inherited keeps the parent's reference. If they ever
    // clone entries, this check stops filtering.
    return Object.fromEntries(Object.entries(args).filter(([argKey, arg]) => arg.index !== index || arg !== inherited[argKey]));
}