封装一个DTO

// response.dto.ts

import {
    CallHandler,
    ExecutionContext,
    Injectable,
    NestInterceptor,
} from "@nestjs/common";
import { FastifyReply } from "fastify";
import { Observable } from "rxjs";
import { map } from "rxjs/operators";
import { getReasonPhrase } from "http-status-codes";
import { instanceToPlain } from "class-transformer";

function getCurrentTimestamp(): number {
    return Date.parse(new Date().toString()) / 1000;
}

@Injectable()
export class TransformInterceptor implements NestInterceptor {
    intercept(
        context: ExecutionContext,
        next: CallHandler<any>
    ): Observable<any> {
        // 获取Fastify的响应对象
        const response: FastifyReply = context
            .switchToHttp()
            .getResponse<FastifyReply>();

        return next.handle().pipe(
            map((originalData: any) => {
                if (
                    originalData &&
                    originalData.code &&
                    originalData.message &&
                    "data" in originalData
                ) {
                    return originalData; // 如果是，直接返回
                }

                // 获取响应状态码
                const statusCode: number = response.statusCode;
                // 获取对应状态码的标准消息
                const message: string = getReasonPhrase(statusCode);

                // 构造标准响应格式
                return {
                    code: statusCode,
                    message: message,
                    data: instanceToPlain(originalData) || null,
                    timestamp: getCurrentTimestamp(),
                };
            })
        );
    }
}

在app.module中引入