import type { EntityMetadata , EntityProperty } from '../typings' ; import { Utils } from '../utils/Utils' ; export interface IConfiguration { get ( key , defaultValue ? ) : any ; } export abstract class MetadataProvider { constructor ( protected readonly config ) { } abstract loadEntityMetadata ( meta , name ) ; /**
     * Re-hydrates missing attributes like `customType` (functions/instances are lost when caching to JSON)
     */ loadFromCache ( meta , cache ) { Object . values ( cache . properties ) . forEach ( prop => { if ( prop . customType ) { prop . customType = meta . properties [ prop . name ] . customType ; } } ) ; Utils . merge ( meta , cache ) ; } useCache ( ) { return this . config . get ( 'cache' ) . enabled ?? false ; } protected async initProperties ( meta , fallback ) { for ( const prop of Object . values ( meta . properties ) ) { if ( Utils . isString ( prop . entity ) ) { prop . type = prop . entity ; } else if ( prop . entity ) { const tmp = prop . entity ( ) ; prop . type = Array . isArray ( tmp ) ? tmp . map ( t => Utils . className ( t ) ) . sort ( ) . join ( ' | ' ) : Utils . className ( tmp ) ; } else if ( ! prop . type ) { await fallback ( prop ) ; } } } }