NestJS+Fastify注册fastify/secure-session时出现类型错误

问题场景 #

在基于Fastify适配器的NestJS应用中注册@fastify/secure-session中间件时，触发类型不兼容错误，具体代码和错误信息如下：

代码片段 #

import { NestFactory } from '@nestjs/core';
import { AppModule } from './app.module';
import { FastifyAdapter, NestFastifyApplication } from '@nestjs/platform-fastify';
import { ConfigService } from '@nestjs/config';
import { ValidationPipe } from '@nestjs/common';
import session from '@fastify/secure-session';
import { session_key } from '@app/keys';

(async () => {
const app = await NestFactory.create<NestFastifyApplication>(AppModule, new FastifyAdapter());
const config = app.get(ConfigService);
const { port } = config.get('http');
app.useLogger(config.get('loglevels'));
app.useGlobalPipes(new ValidationPipe({ whitelist: true }));
app.enableShutdownHooks();
app.register(session, { secret: 'asdawdasadgfhafjwefihdauhadiwudhaadoiuahwdasiefuhasefiu', salt: 'asdawdafowsuFIU' });
await app.listen(port);
})();

错误信息 #

Argument of type 'FastifySecureSession' is not assignable to parameter of type 'FastifyPluginCallback<SecureSessionPluginOptions | (SecureSessionPluginOptions & Required<Pick<SecureSessionPluginOptions, "sessionName">>)[]> | FastifyPluginAsync<...> | Promise<...> | Promise<...>'.
  Type 'FastifySecureSession' is not assignable to type 'FastifyPluginCallback<SecureSessionPluginOptions | (SecureSessionPluginOptions & Required<Pick<SecureSessionPluginOptions, "sessionName">>)[]>'.
    Types of parameters 'instance' and 'instance' are incompatible.
      Type 'FastifyInstance<RawServerDefault, IncomingMessage, ServerResponse<IncomingMessage>, FastifyBaseLogger, FastifyTypeProviderDefault>' is missing the following properties from type 'FastifyInstance<RawServerDefault, IncomingMessage, ServerResponse<IncomingMessage>, FastifyBaseLogger, FastifyTypeProviderDefault>': serializeCookie, parseCookie, createSecureSession, decodeSecureSession, and 3 more.
    14 |   app.useGlobalPipes(new ValidationPipe({ whitelist: true }));
    15 |   app.enableShutdownHooks();
  > 16 |   app.register(session, { key: 'asdawdasadgfhafjwefihdauhadiwudhaadoiuahwdasiefuhasefiu', salt: 'asdawdafowsuFIU' });
       |                ^^^^^^^
    17 |   await app.listen(port);
    18 | })();
    19 |

解决方案 #

1. 对齐Fastify相关包版本 #

类型不兼容的核心原因通常是@fastify/secure-session与NestJS集成的fastify版本不匹配：

• 查看@nestjs/platform-fastify的peer依赖版本：打开node_modules/@nestjs/platform-fastify/package.json，找到fastify的版本范围。
• 安装对应兼容版本的@fastify/secure-session，例如Nest依赖fastify@4.x时，需安装@fastify/secure-session@7.x版本（具体兼容关系参考插件官方文档）。
• 执行安装命令：

npm install @fastify/secure-session@<兼容版本号>
# 或使用yarn
yarn add @fastify/secure-session@<兼容版本号>

2. 修正插件导入方式 #

部分版本的@fastify/secure-session需要使用命名导入或全量导入，替换原导入语句：

import * as session from '@fastify/secure-session';

3. 直接操作底层Fastify实例 #

绕过Nest封装的类型校验，直接获取Fastify原生实例进行插件注册：

const fastifyInstance = app.getHttpAdapter().getInstance();
await fastifyInstance.register(session, { 
  secret: 'asdawdasadgfhafjwefihdauhadiwudhaadoiuahwdasiefuhasefiu', 
  salt: 'asdawdafowsuFIU' 
});

4. 临时类型断言（不推荐长期使用） #

若上述方案无效，可临时通过类型断言绕过类型检查，仅用于调试场景：

app.register(session as any, { 
  secret: 'asdawdasadgfhafjwefihdauhadiwudhaadoiuahwdasiefuhasefiu', 
  salt: 'asdawdafowsuFIU' 
});

内容的提问来源于stack exchange，提问作者Andy95