Implement dedicated interceptor for multiple file upload (#273)

lib/gcloud-storage-files.interceptor.ts

@@ -0,0 +1,45 @@
+import { CallHandler, ExecutionContext, Injectable, Logger, mixin, NestInterceptor, Type } from '@nestjs/common';
+import { FilesInterceptor } from '@nestjs/platform-express';
+import { MulterOptions } from '@nestjs/platform-express/multer/interfaces/multer-options.interface';
+import { Observable } from 'rxjs';
+
+import { GCloudStoragePerRequestOptions } from './gcloud-storage.interface';
+import { GCloudStorageService } from './gcloud-storage.service';
+
+export function GCloudStorageFilesInterceptor(
+  fieldName: string,
+  localOptions?: MulterOptions,
+  gcloudStorageOptions?: Partial<GCloudStoragePerRequestOptions>,
+): Type<NestInterceptor> {
+  @Injectable()
+  class MixinInterceptor implements NestInterceptor {
+    public interceptor: NestInterceptor;
+
+    constructor(private readonly gcloudStorage: GCloudStorageService) {
+      this.interceptor = new (FilesInterceptor(fieldName, 20, localOptions))();
+    }
+
+    async intercept(context: ExecutionContext, next: CallHandler): Promise<Observable<any>> {
+      (await this.interceptor.intercept(context, next)) as Observable<any>;
+
+      const request = context.switchToHttp().getRequest();
+
+      const files = request[fieldName];
+
+      if (!files.length) {
+        Logger.error(
+          'GCloudStorageFilesInterceptor',
+          `Can not intercept field "${fieldName}". Did you specify the correct field name in @GCloudStorageFilesInterceptor('${fieldName}')?`,
+        );
+        return;
+      }
+
+      for (const file of files) file.storageUrl = await this.gcloudStorage.upload(file, gcloudStorageOptions);
+
+      return next.handle();
+    }
+  }
+
+  const Interceptor = mixin(MixinInterceptor);
+  return Interceptor as Type<NestInterceptor>;
+}

lib/index.ts

@@ -4,3 +4,4 @@ export * from './gcloud-storage.interface';
 export * from './gcloud-storage.module';
 export * from './gcloud-storage.service';
 export * from './gcloud-stroage-file.interceptor';
+export * from './gcloud-storage-files.interceptor';