feat(mobile): use cached asset info if unchanged instead of downloading all assets (#1017)

* feat(mobile): use cached asset info if unchanged instead of downloading all assets

This adds an HTTP ETag to the getAllAssets endpoint and client-side support in the app.
If locally cache content is identical to the content on the server, the potentially large list of all assets does not need to be downloaded.

* use ts import instead of require

server/apps/immich/src/api-v1/asset/asset.controller.ts

@@ -14,6 +14,7 @@ import {
   Header,
   Put,
   UploadedFiles,
+  Request,
 } from '@nestjs/common';
 import { Authenticated } from '../../decorators/authenticated.decorator';
 import { AssetService } from './asset.service';
@@ -21,12 +22,12 @@ import { FileFieldsInterceptor } from '@nestjs/platform-express';
 import { assetUploadOption } from '../../config/asset-upload.config';
 import { AuthUserDto, GetAuthUser } from '../../decorators/auth-user.decorator';
 import { ServeFileDto } from './dto/serve-file.dto';
-import { Response as Res } from 'express';
+import { Response as Res, Request as Req } from 'express';
 import { BackgroundTaskService } from '../../modules/background-task/background-task.service';
 import { DeleteAssetDto } from './dto/delete-asset.dto';
 import { SearchAssetDto } from './dto/search-asset.dto';
 import { CheckDuplicateAssetDto } from './dto/check-duplicate-asset.dto';
-import { ApiBearerAuth, ApiBody, ApiConsumes, ApiTags } from '@nestjs/swagger';
+import { ApiBearerAuth, ApiBody, ApiConsumes, ApiHeader, ApiResponse, ApiTags } from '@nestjs/swagger';
 import { CuratedObjectsResponseDto } from './response-dto/curated-objects-response.dto';
 import { CuratedLocationsResponseDto } from './response-dto/curated-locations-response.dto';
 import { AssetResponseDto } from './response-dto/asset-response.dto';
@@ -49,6 +50,7 @@ import {
   IMMICH_ARCHIVE_FILE_COUNT,
   IMMICH_CONTENT_LENGTH_HINT,
 } from '../../constants/download.constant';
+import { etag } from '../../utils/etag';
 
 @Authenticated()
 @ApiBearerAuth()
@@ -168,8 +170,28 @@ export class AssetController {
    * Get all AssetEntity belong to the user
    */
   @Get('/')
-  async getAllAssets(@GetAuthUser() authUser: AuthUserDto): Promise<AssetResponseDto[]> {
-    return await this.assetService.getAllAssets(authUser);
+  @ApiHeader({
+    name: 'if-none-match',
+    description: 'ETag of data already cached on the client',
+    required: false,
+    schema: { type: 'string' },
+  })
+  @ApiResponse({
+    status: 200,
+    headers: { ETag: { required: true, schema: { type: 'string' } } },
+    type: [AssetResponseDto],
+  })
+  async getAllAssets(@GetAuthUser() authUser: AuthUserDto, @Response() response: Res, @Request() request: Req) {
+    const assets = await this.assetService.getAllAssets(authUser);
+    const clientEtag = request.headers['if-none-match'];
+    const json = JSON.stringify(assets);
+    const serverEtag = await etag(json);
+    response.setHeader('ETag', serverEtag);
+    if (clientEtag === serverEtag) {
+      response.status(304).end();
+    } else {
+      response.contentType('application/json').status(200).send(json);
+    }
   }
 
   @Post('/time-bucket')

server/apps/immich/src/api-v1/asset/response-dto/asset-response.dto.ts

@@ -19,10 +19,10 @@ export class AssetResponseDto {
   mimeType!: string | null;
   duration!: string;
   webpPath!: string | null;
-  encodedVideoPath!: string | null;
+  encodedVideoPath?: string | null;
   exifInfo?: ExifResponseDto;
   smartInfo?: SmartInfoResponseDto;
-  livePhotoVideoId!: string | null;
+  livePhotoVideoId?: string | null;
 }
 
 export function mapAsset(entity: AssetEntity): AssetResponseDto {

server/apps/immich/src/api-v1/user/response-dto/user-response.dto.ts

@@ -9,7 +9,7 @@ export class UserResponseDto {
   profileImagePath!: string;
   shouldChangePassword!: boolean;
   isAdmin!: boolean;
-  deletedAt!: Date | null;
+  deletedAt?: Date;
 }
 
 export function mapUser(entity: UserEntity): UserResponseDto {
@@ -22,6 +22,6 @@ export function mapUser(entity: UserEntity): UserResponseDto {
     profileImagePath: entity.profileImagePath,
     shouldChangePassword: entity.shouldChangePassword,
     isAdmin: entity.isAdmin,
-    deletedAt: entity.deletedAt || null,
+    deletedAt: entity.deletedAt,
   };
 }

server/apps/immich/src/types/index.d.ts

@@ -0,0 +1,5 @@
+declare module 'crypto' {
+  namespace webcrypto {
+    const subtle: SubtleCrypto;
+  }
+}

server/apps/immich/src/utils/etag.ts

@@ -0,0 +1,10 @@
+import { webcrypto } from 'node:crypto';
+const { subtle } = webcrypto;
+
+export async function etag(text: string): Promise<string> {
+    const encoder = new TextEncoder();
+    const data = encoder.encode(text);
+    const buffer = await subtle.digest('SHA-1', data);
+    const hash = Buffer.from(buffer).toString('base64').slice(0, 27);
+    return `"${data.length}-${hash}"`;
+}