Use libs for mapping between Dtos and Entities

[pschild]

Client	Controller	Service	Repository	Database
Dto	Dto <=> Entity (Mapping)	Entity	Entity

• https://stackoverflow.com/questions/51113506/nodejs-map-dtos-to-typeorm-entities
• https://github.com/typestack/class-transformer
• https://github.com/typestack/class-validator

[pschild]

Alternative: Use NestJs's interceptors:

import { Injectable, NestInterceptor, ExecutionContext } from '@nestjs/common';
import { Observable } from 'rxjs';
import { mergeMap, map } from 'rxjs/operators';
import { FolderDto } from './dto/Folder.dto';
import { FolderService } from './folder/folder.service';
import { Folder } from './entity/folder.entity';

@Injectable()
export class TransformInterceptor implements NestInterceptor<Folder, FolderDto | FolderDto[]> {

    constructor(
        private readonly folderService: FolderService
    ) { }

    intercept(context: ExecutionContext, call$: Observable<Folder|Folder[]>): Observable<FolderDto | FolderDto[]> {
        return call$.pipe(
            map(data => {
                if (Array.isArray(data)) {
                    return data;
                } else {
                    return [data];
                }
            }),
            mergeMap(entity => {
                return this.mapAllToDto(entity);
            })
        );
    }

    mapAllToDto(entities: Folder[]): Promise<FolderDto[]> {
        if (entities) {
            const r = entities.map(async (entity: Folder) => await this.mapToDto(entity));
            return Promise.all(r);
        }
    }

    async mapToDto(entity: Folder): Promise<FolderDto> {
        if (entity) {
            const dto = new FolderDto();
            dto.id = entity.id;
            dto.name = entity.name;
            dto.absolutePath = await this.folderService.buildPathByFolderId(entity.id);
            dto.parent = await this.mapToDto(entity.parent);
            dto.children = await this.mapAllToDto(entity.children);
            dto.dateAdded = entity.dateAdded;
            return dto;
        }
    }
}

[pschild]

Check: https://github.com/loedeman/AutoMapper/wiki

[pschild]

Maybe it's enough to only pass the IDs instead of complete related/nested objects, e.g. pass the parent folder ID in ImageDto

[pschild]

Check which properties of an Entity are really needed by the client

[pschild]

Wiat for plainToClass(newType, item, { excludeExtraneousValues: true }) to be implemented by class-transformer package. Then remove @Exclude annotations from DTOs.