Use context lang as primary default for service

docs/quick-start.mdx

@@ -326,11 +326,16 @@ import { I18nContext, I18nService } from 'nestjs-i18n';
 export class AppService {
   constructor(private readonly i18n: I18nService) {}
   getHello(): string {
-    return this.i18n.t('test.HELLO',{ lang:   I18nContext.current().lang });
+    return this.i18n.t('test.HELLO');
+  }
+
+  getHelloInSpecificLanguage(): string {
+    return this.i18n.t('test.HELLO',{ lang: "en" });
   }
 }
 ```
 
+
 ## Translate options
 
 ```typescript

src/services/i18n.service.ts

@@ -8,7 +8,12 @@ import {
   take,
   takeUntil,
 } from 'rxjs';
-import { I18nOptions, I18nTranslation, I18nValidationError } from '..';
+import {
+  I18nContext,
+  I18nOptions,
+  I18nTranslation,
+  I18nValidationError,
+} from '..';
 import {
   I18N_LANGUAGES,
   I18N_LANGUAGES_SUBJECT,
@@ -75,7 +80,7 @@ export class I18nService<K = Record<string, unknown>>
     options?: TranslateOptions,
   ): IfAnyOrNever<R, string, R> {
     options = {
-      lang: this.i18nOptions.fallbackLanguage,
+      lang: I18nContext.current()?.lang || this.i18nOptions.fallbackLanguage,
       ...options,
     };
 

tests/app/cats/cat.resolver.ts

@@ -39,6 +39,14 @@ export class CatResolver {
     return cat;
   }
 
+  @Query('catUsingService')
+  async getCatUsingService(@Args('id') id: number) {
+    const cat = await this.catService.findById(id);
+    // we manually overwrite this property to indicate a value that is translated!
+    cat.description = this.i18nService.translate('test.cat');
+    return cat;
+  }
+
   @Mutation('createCat')
   async create(@Args('createCatInput') args: CreateCatInput): Promise<any> {
     await this.pubSub.publish('catAdded', { catAdded: args.name });

tests/app/cats/cat.types.graphql

@@ -9,6 +9,7 @@ type Query {
   cats: [Cat]
   cat(id: Int!): Cat
   catUsingContext(id: Int!): Cat
+  catUsingService(id: Int!): Cat
 }
 
 type Mutation {
@@ -23,4 +24,4 @@ type Subscription {
 input CreateCatInput {
   name: String
   age: Int
-}
+}

tests/app/controllers/hello.controller.ts

@@ -22,7 +22,10 @@ import { CreateUserDto } from '../dto/create-user.dto';
 import { TestException, TestExceptionFilter } from '../filter/test.filter';
 import { TestGuard } from '../guards/test.guard';
 import { Hero, HeroById } from '../interfaces/hero.interface';
-import { exampleErrorFormatter, exampleResponseBodyFormatter } from '../examples/example.functions';
+import {
+  exampleErrorFormatter,
+  exampleResponseBodyFormatter,
+} from '../examples/example.functions';
 import { TestInterceptor } from '../interceptors/test.interceptor';
 
 @Controller('hello')
@@ -35,6 +38,11 @@ export class HelloController {
     return this.i18n.translate('test.HELLO', { lang });
   }
 
+  @Get('/no-lang-for-service')
+  helloNoLangForService(): any {
+    return this.i18n.translate('test.HELLO');
+  }
+
   @Get('/typed')
   helloTyped(@I18nLang() lang: string): string {
     return this.i18n.translate('test.HELLO', { lang });
@@ -59,6 +67,11 @@ export class HelloController {
     return this.i18n.t('test.HELLO', { lang });
   }
 
+  @Get('/short/no-lang-for-service')
+  helloShortNoLangForService(): any {
+    return this.i18n.t('test.HELLO');
+  }
+
   @Get('/short/typed')
   helloShortTyped(@I18nLang() lang: string): string {
     return this.i18n.t('test.HELLO', { lang });
@@ -228,4 +241,18 @@ export class HelloController {
     ];
     return items.find(({ id }) => id === data.id);
   }
+
+  @GrpcMethod('HeroesService', 'FindOneTranslatedWithService')
+  findOneTranslatedWithService(@Payload() data: HeroById): Hero {
+    const items = [
+      {
+        id: 1,
+        name: this.i18n.t('test.set-up-password.heading', {
+          args: { username: 'John' },
+        }),
+      },
+      { id: 2, name: 'Doe' },
+    ];
+    return items.find(({ id }) => id === data.id);
+  }
 }

tests/app/hero.proto

@@ -4,6 +4,7 @@ package hero;
 
 service HeroesService {
   rpc FindOne (HeroById) returns (Hero) {}
+  rpc FindOneTranslatedWithService (HeroById) returns (Hero) {}
 }
 
 message HeroById {

tests/app/interfaces/hero.interface.ts

@@ -12,4 +12,8 @@ export interface HeroById {
 
 export interface HeroService {
   findOne(data: HeroById, metadata: Metadata): Observable<Hero>;
+  findOneTranslatedWithService(
+    data: HeroById,
+    metadata: Metadata,
+  ): Observable<Hero>;
 }

tests/i18n-express.e2e.spec.ts

@@ -617,6 +617,82 @@ describe('i18n module e2e express', () => {
       .expect({ lang: 'nl' });
   });
 
+  it(`/GET hello/no-lang-for-service should return fallback language`, () => {
+    return request(app.getHttpServer())
+      .get('/hello/no-lang-for-service')
+      .expect(200)
+      .expect('Hello');
+  });
+
+  it(`/GET hello/no-lang-for-service should return translation when providing query resolver`, () => {
+    return request(app.getHttpServer())
+      .get('/hello/no-lang-for-service?lang=nl')
+      .expect(200)
+      .expect('Hallo');
+  });
+
+  it(`/GET hello/no-lang-for-service should return translation when providing x-custom-lang`, () => {
+    return request(app.getHttpServer())
+    .get('/hello/no-lang-for-service')
+      .set('x-custom-lang', 'nl')
+      .expect(200)
+      .expect('Hallo');
+  });
+
+  it(`/GET hello/no-lang-for-service should return translation when providing accept-language`, () => {
+    return request(app.getHttpServer())
+      .get('/hello/no-lang-for-service')
+      .set('accept-language', 'nl')
+      .expect(200)
+      .expect('Hallo');
+  });
+
+  it(`/GET hello/no-lang-for-service should return translation when providing cookie`, () => {
+    return request(app.getHttpServer())
+      .get('/hello/no-lang-for-service')
+      .set('Cookie', ['lang=nl'])
+      .expect(200)
+      .expect('Hallo');
+  });
+
+  it(`/GET hello/short/no-lang-for-service should return fallback language`, () => {
+    return request(app.getHttpServer())
+      .get('/hello/short/no-lang-for-service')
+      .expect(200)
+      .expect('Hello');
+  });
+
+  it(`/GET hello/short/no-lang-for-service should return translation when providing query resolver`, () => {
+    return request(app.getHttpServer())
+      .get('/hello/short/no-lang-for-service?lang=nl')
+      .expect(200)
+      .expect('Hallo');
+  });
+
+  it(`/GET hello/short/no-lang-for-service should return translation when providing x-custom-lang`, () => {
+    return request(app.getHttpServer())
+    .get('/hello/short/no-lang-for-service')
+      .set('x-custom-lang', 'nl')
+      .expect(200)
+      .expect('Hallo');
+  });
+
+  it(`/GET hello/short/no-lang-for-service should return translation when providing accept-language`, () => {
+    return request(app.getHttpServer())
+      .get('/hello/short/no-lang-for-service')
+      .set('accept-language', 'nl')
+      .expect(200)
+      .expect('Hallo');
+  });
+
+  it(`/GET hello/short/no-lang-for-service should return translation when providing cookie`, () => {
+    return request(app.getHttpServer())
+      .get('/hello/short/no-lang-for-service')
+      .set('Cookie', ['lang=nl'])
+      .expect(200)
+      .expect('Hallo');
+  });
+
   it('/POST cats with age 2 should error', async () => {
     await request(app.getHttpServer())
       .post('/cats')

tests/i18n-fastify.e2e.spec.ts

@@ -621,6 +621,82 @@ describe('i18n module e2e fastify', () => {
       .expect({ lang: 'nl' });
   });
 
+  it(`/GET hello/no-lang-for-service should return fallback language`, () => {
+    return request(app.getHttpServer())
+      .get('/hello/no-lang-for-service')
+      .expect(200)
+      .expect('Hello');
+  });
+
+  it(`/GET hello/no-lang-for-service should return translation when providing query resolver`, () => {
+    return request(app.getHttpServer())
+      .get('/hello/no-lang-for-service?lang=nl')
+      .expect(200)
+      .expect('Hallo');
+  });
+
+  it(`/GET hello/no-lang-for-service should return translation when providing x-custom-lang`, () => {
+    return request(app.getHttpServer())
+    .get('/hello/no-lang-for-service')
+      .set('x-custom-lang', 'nl')
+      .expect(200)
+      .expect('Hallo');
+  });
+
+  it(`/GET hello/no-lang-for-service should return translation when providing accept-language`, () => {
+    return request(app.getHttpServer())
+      .get('/hello/no-lang-for-service')
+      .set('accept-language', 'nl')
+      .expect(200)
+      .expect('Hallo');
+  });
+
+  it(`/GET hello/no-lang-for-service should return translation when providing cookie`, () => {
+    return request(app.getHttpServer())
+      .get('/hello/no-lang-for-service')
+      .set('Cookie', ['lang=nl'])
+      .expect(200)
+      .expect('Hallo');
+  });
+
+  it(`/GET hello/short/no-lang-for-service should return fallback language`, () => {
+    return request(app.getHttpServer())
+      .get('/hello/short/no-lang-for-service')
+      .expect(200)
+      .expect('Hello');
+  });
+
+  it(`/GET hello/short/no-lang-for-service should return translation when providing query resolver`, () => {
+    return request(app.getHttpServer())
+      .get('/hello/short/no-lang-for-service?lang=nl')
+      .expect(200)
+      .expect('Hallo');
+  });
+
+  it(`/GET hello/short/no-lang-for-service should return translation when providing x-custom-lang`, () => {
+    return request(app.getHttpServer())
+    .get('/hello/short/no-lang-for-service')
+      .set('x-custom-lang', 'nl')
+      .expect(200)
+      .expect('Hallo');
+  });
+
+  it(`/GET hello/short/no-lang-for-service should return translation when providing accept-language`, () => {
+    return request(app.getHttpServer())
+      .get('/hello/short/no-lang-for-service')
+      .set('accept-language', 'nl')
+      .expect(200)
+      .expect('Hallo');
+  });
+
+  it(`/GET hello/short/no-lang-for-service should return translation when providing cookie`, () => {
+    return request(app.getHttpServer())
+      .get('/hello/short/no-lang-for-service')
+      .set('Cookie', ['lang=nl'])
+      .expect(200)
+      .expect('Hallo');
+  });
+
   it('/POST cats with age 2 should error', async () => {
     await request(app.getHttpServer())
       .post('/cats')

tests/i18n-gql.e2e.spec.ts

@@ -464,6 +464,89 @@ describe('i18n module e2e graphql', () => {
       });
   });
 
+  it(`should query a particular cat (using injected I18nService) in fallback language`, () => {
+    return request(app.getHttpServer())
+      .post('/graphql')
+      .send({
+        operationName: null,
+        variables: {},
+        query: '{catUsingService(id:2){id,name,age,description}}',
+      })
+      .expect(200, {
+        data: {
+          catUsingService: {
+            id: 2,
+            name: 'bar',
+            age: 6,
+            description: 'Cat',
+          },
+        },
+      });
+  });
+
+  it(`should query a particular cat (using injected I18nService) in NL with x-custom-lang header`, () => {
+    return request(app.getHttpServer())
+      .post('/graphql')
+      .set('x-custom-lang', 'nl')
+      .send({
+        operationName: null,
+        variables: {},
+        query: '{catUsingService(id:2){id,name,age,description}}',
+      })
+      .expect(200, {
+        data: {
+          catUsingService: {
+            id: 2,
+            name: 'bar',
+            age: 6,
+            description: 'Kat',
+          },
+        },
+      });
+  });
+
+  it(`should query a particular cat (using injected I18nService) in NL with cookie`, () => {
+    return request(app.getHttpServer())
+      .post('/graphql')
+      .set('Cookie', ['lang=nl'])
+      .send({
+        operationName: null,
+        variables: {},
+        query: '{catUsingService(id:2){id,name,age,description}}',
+      })
+      .expect(200, {
+        data: {
+          catUsingService: {
+            id: 2,
+            name: 'bar',
+            age: 6,
+            description: 'Kat',
+          },
+        },
+      });
+  });
+
+  it(`should query a particular cat (using injected I18nService) in NL with accept-language header`, () => {
+    return request(app.getHttpServer())
+      .post('/graphql')
+      .set('accept-language', 'nl')
+      .send({
+        operationName: null,
+        variables: {},
+        query: '{catUsingService(id:2){id,name,age,description}}',
+      })
+      .expect(200, {
+        data: {
+          catUsingService: {
+            id: 2,
+            name: 'bar',
+            age: 6,
+            description: 'Kat',
+          },
+        },
+      });
+  });
+
   afterAll(async () => {
     apollo.stop();
     await subscriptionClient.dispose();