refactor: simplify booru tag DTO handling

src/booru/dto/booru-queries.dto.spec.ts

@@ -1,68 +1,67 @@
-import { plainToInstance } from 'class-transformer'
+import { Controller, Get, Query } from '@nestjs/common'
+import { FastifyAdapter, NestFastifyApplication } from '@nestjs/platform-fastify'
+import { Test, TestingModule } from '@nestjs/testing'
+import { createAppValidationPipe } from '../../common/validation'
 import { booruQueryValuesPostsDTO } from './booru-queries.dto'
 
-describe('booruQueryValuesPostsDTO', () => {
-  describe('tags transform', () => {
-    it('should normalize a single tag string into an array', () => {
-      const dto = plainToInstance(booruQueryValuesPostsDTO, {
-        tags: 'panty_&_stocking_with_garterbelt'
-      })
+@Controller('dto-test')
+class BooruQueriesTestController {
+  @Get('posts')
+  getPosts(@Query() queries: booruQueryValuesPostsDTO) {
+    return { tags: queries.tags }
+  }
+}
 
-      expect(dto.tags).toEqual(['panty_&_stocking_with_garterbelt'])
-    })
-
-    it('should split pipe-separated tags', () => {
-      const dto = plainToInstance(booruQueryValuesPostsDTO, {
-        tags: 'panty_&_stocking_with_garterbelt|rating:safe'
-      })
+describe('booruQueryValuesPostsDTO request handling', () => {
+  let app: NestFastifyApplication
 
-      expect(dto.tags).toEqual(['panty_&_stocking_with_garterbelt', 'rating:safe'])
-    })
+  beforeEach(async () => {
+    const moduleRef: TestingModule = await Test.createTestingModule({
+      controllers: [BooruQueriesTestController]
+    }).compile()
 
-    it('should normalize array tag inputs and keep tag array shape', () => {
-      const dto = plainToInstance(booruQueryValuesPostsDTO, {
-        tags: ['panty_&_stocking_with_garterbelt|rating:safe', 'score:>100']
-      })
+    app = moduleRef.createNestApplication<NestFastifyApplication>(new FastifyAdapter())
+    app.useGlobalPipes(createAppValidationPipe())
 
-      expect(dto.tags).toEqual(['panty_&_stocking_with_garterbelt', 'rating:safe', 'score:>100'])
-    })
+    await app.init()
+    await app.getHttpAdapter().getInstance().ready()
+  })
 
-    it('should normalize non-string tag input without throwing', () => {
-      const dto = plainToInstance(booruQueryValuesPostsDTO, {
-        tags: 123
-      })
+  afterEach(async () => {
+    await app.close()
+  })
 
-      expect(dto.tags).toEqual(['123'])
+  it('should rely on request parsing for percent-decoding and split tags by pipe', async () => {
+    const response = await app.inject({
+      method: 'GET',
+      url: '/dto-test/posts?baseEndpoint=gelbooru.com&tags=panty_%26_stocking_with_garterbelt%7Crating%3Asafe'
     })
 
-    it('should keep non-encoded percent tags unchanged', () => {
-      const dto = plainToInstance(booruQueryValuesPostsDTO, {
-        tags: '100%_real'
-      })
+    const body = JSON.parse(response.body)
 
-      expect(dto.tags).toEqual(['100%_real'])
-    })
-
-    it('should keep malformed percent tag values unchanged', () => {
-      const dto = plainToInstance(booruQueryValuesPostsDTO, {
-        tags: 'bad%%'
-      })
+    expect(response.statusCode).toBe(200)
+    expect(body.tags).toEqual(['panty_&_stocking_with_garterbelt', 'rating:safe'])
+  })
 
-      expect(dto.tags).toEqual(['bad%%'])
+  it('should normalize repeated tags query params and split each entry', async () => {
+    const response = await app.inject({
+      method: 'GET',
+      url: '/dto-test/posts?baseEndpoint=gelbooru.com&tags=artist%3Afoo%7Crating%3Asafe&tags=score%3A%3E100'
     })
 
-    it('should return undefined when tags is undefined', () => {
-      const dto = plainToInstance(booruQueryValuesPostsDTO, {})
-
-      expect(dto.tags).toBeUndefined()
-    })
+    const body = JSON.parse(response.body)
 
-    it('should return null when tags is null', () => {
-      const dto = plainToInstance(booruQueryValuesPostsDTO, {
-        tags: null
-      })
+    expect(response.statusCode).toBe(200)
+    expect(body.tags).toEqual(['artist:foo', 'rating:safe', 'score:>100'])
+  })
 
-      expect(dto.tags).toBeNull()
+  it('should reject empty tags created after pipe splitting', async () => {
+    const response = await app.inject({
+      method: 'GET',
+      url: '/dto-test/posts?baseEndpoint=gelbooru.com&tags=tag1%7C'
     })
+
+    expect(response.statusCode).toBe(400)
+    expect(response.body).toContain('tags should not contain')
   })
 })

src/booru/dto/booru-queries.dto.ts

@@ -180,14 +180,15 @@ export class booruQueryValuesPostsDTO extends booruQueriesDTO {
   @IsArray()
   @ArrayNotEmpty()
   @ArrayNotContains([''])
+  @IsString({ each: true })
   @Transform(({ value }) => {
     if (value === undefined || value === null) {
       return value
     }
 
-    return (Array.isArray(value) ? value : [value])
-      .map((tag) => (typeof tag === 'string' ? tag : String(tag)))
-      .flatMap((tag) => tag.trim().split('|'))
+    return (Array.isArray(value) ? value : [value]).flatMap((tag) =>
+      typeof tag === 'string' ? tag.trim().split('|') : [tag]
+    )
   })
   @IsOptional()
   readonly tags: IBooruQueryValues['posts']['tags']

src/common/validation.ts

@@ -0,0 +1,11 @@
+import { ValidationPipe, ValidationPipeOptions } from '@nestjs/common'
+
+export const APP_VALIDATION_PIPE_OPTIONS: ValidationPipeOptions = {
+  transform: true,
+  whitelist: true,
+  forbidNonWhitelisted: true
+}
+
+export function createAppValidationPipe() {
+  return new ValidationPipe(APP_VALIDATION_PIPE_OPTIONS)
+}

src/main.ts

@@ -1,4 +1,3 @@
-import { ValidationPipe } from '@nestjs/common'
 import { CorsOptions } from '@nestjs/common/interfaces/external/cors-options.interface'
 import { NestFactory } from '@nestjs/core'
 import { ConfigService } from '@nestjs/config'
@@ -10,6 +9,7 @@ import { AppModule } from './app.module'
 import { escapeRegExp } from 'lodash'
 import { AppClusterService } from './cluster.service'
 import { join } from 'path'
+import { createAppValidationPipe } from './common/validation'
 
 async function bootstrap() {
   const app = await NestFactory.create<NestFastifyApplication>(AppModule, new FastifyAdapter())
@@ -40,15 +40,7 @@ async function bootstrap() {
 
   app.enableCors(corsOptions)
 
-  app.useGlobalPipes(
-    new ValidationPipe({
-      transform: true, // Transform to DTO type
-      // transformOptions: { enableImplicitConversion: true },
-
-      whitelist: true, // Remove unnecessary properties
-      forbidNonWhitelisted: true // Sends "property <property> should not exist." error
-    })
-  )
+  app.useGlobalPipes(createAppValidationPipe())
 
   await app.listen(configService.get<number>('PORT') ?? 3000, '0.0.0.0')
 }