feat(server): random assets API (#4184)

* feat(server): get random assets API

* Fix tests

* Use correct validation annotation

* Fix offset use in query

* Update API specs

* Fix typo

* Random assets e2e tests

* Improve e2e tests

server/src/domain/asset/asset.repository.ts

@@ -78,6 +78,7 @@ export interface IAssetRepository {
   getByUserId(pagination: PaginationOptions, userId: string): Paginated<AssetEntity>;
   getWithout(pagination: PaginationOptions, property: WithoutProperty): Paginated<AssetEntity>;
   getWith(pagination: PaginationOptions, property: WithProperty, libraryId?: string): Paginated<AssetEntity>;
+  getRandom(userId: string, count: number): Promise<AssetEntity[]>;
   getFirstAssetForAlbumId(albumId: string): Promise<AssetEntity | null>;
   getLastUpdatedAssetForAlbumId(albumId: string): Promise<AssetEntity | null>;
   getByLibraryId(libraryIds: string[]): Promise<AssetEntity[]>;

server/src/domain/asset/asset.service.ts

@@ -284,6 +284,11 @@ export class AssetService {
     return mapStats(stats);
   }
 
+  async getRandom(authUser: AuthUserDto, count: number): Promise<AssetResponseDto[]> {
+    const assets = await this.assetRepository.getRandom(authUser.id, count);
+    return assets.map((a) => mapAsset(a));
+  }
+
   async update(authUser: AuthUserDto, id: string, dto: UpdateAssetDto): Promise<AssetResponseDto> {
     await this.access.requirePermission(authUser, Permission.ASSET_UPDATE, id);
 

server/src/domain/asset/dto/asset.dto.ts

@@ -1,4 +1,5 @@
-import { IsBoolean, IsString } from 'class-validator';
+import { Type } from 'class-transformer';
+import { IsBoolean, IsInt, IsPositive, IsString } from 'class-validator';
 import { Optional } from '../../domain.util';
 import { BulkIdsDto } from '../response-dto';
 
@@ -25,3 +26,11 @@ export class UpdateAssetDto {
   @IsString()
   description?: string;
 }
+
+export class RandomAssetsDto {
+  @Optional()
+  @IsInt()
+  @IsPositive()
+  @Type(() => Number)
+  count?: number;
+}

server/src/immich/controllers/asset.controller.ts

@@ -13,6 +13,7 @@ import {
   MapMarkerResponseDto,
   MemoryLaneDto,
   MemoryLaneResponseDto,
+  RandomAssetsDto,
   TimeBucketAssetDto,
   TimeBucketDto,
   TimeBucketResponseDto,
@@ -41,6 +42,11 @@ export class AssetController {
     return this.service.getMemoryLane(authUser, dto);
   }
 
+  @Get('random')
+  getRandom(@AuthUser() authUser: AuthUserDto, @Query() dto: RandomAssetsDto): Promise<AssetResponseDto[]> {
+    return this.service.getRandom(authUser, dto.count ?? 1);
+  }
+
   @SharedLinkRoute()
   @Post('download/info')
   getDownloadInfo(@AuthUser() authUser: AuthUserDto, @Body() dto: DownloadInfoDto): Promise<DownloadResponseDto> {

server/src/infra/repositories/asset.repository.ts

@@ -429,6 +429,17 @@ export class AssetRepository implements IAssetRepository {
     return result;
   }
 
+  getRandom(ownerId: string, count: number): Promise<AssetEntity[]> {
+    // can't use queryBuilder because of custom OFFSET clause
+    return this.repository.query(
+      `SELECT *
+       FROM assets
+       WHERE "ownerId" = $1
+       OFFSET FLOOR(RANDOM() * (SELECT GREATEST(COUNT(*) - 1, 0) FROM ASSETS)) LIMIT $2`,
+      [ownerId, count],
+    );
+  }
+
   getTimeBuckets(options: TimeBucketOptions): Promise<TimeBucketItem[]> {
     const truncateValue = truncateMap[options.size];