Nestjs Multer Custom File Upload

// Example file upload using Multer in NodeJs using NestJs here

    @UseGuards(JsonWebToken.JwtAuthentication)
    @Version('1')
    @Post()
    @UseInterceptors(
        Multer.fields(
            [
                { name: 'photo', maxCount: 1 },
                { name: 'document', maxCount: 1 }
            ],
            {
                storage: Multer.diskStorage,
                fileFilter: Multer.fileFilter
            }
        )
    )
    async fileUpload(
        @Res() res: Response,
        @Body() body: Record<string ,any>,
        @UploadedFiles() files: { photo: Express.Multer.File[]; document: Express.Multer.File[] }
    ): Promise<OutgoingMessage> {
        try {
            const serviceResponse: APIResponse = await this.service.fileUpload(body, files)
            return res.status(serviceResponse.stat_code).json(serviceResponse)
        } catch (e: any) {
            return res.status(e.stat_code).json(e)
        }
    }
}


// Multer custom library here

import 'dotenv/config.js'
import { MulterModule, FileFieldsInterceptor, FilesInterceptor, FileInterceptor } from '@nestjs/platform-express'
import { mimeTypeSupport } from '@helpers/helper.mimeType'
import aws from 'aws-sdk'
import { Request } from 'express'
import multer from 'multer'
import multerS3 from 'multer-s3'
import fs from 'fs'

aws.config.update({
    accessKeyId: process.env.AWS_ACCESS_KEY_ID,
    secretAccessKey: process.env.AWS_ACCESS_KEY
})

export class Multer {
    static typeModule = MulterModule
    static register = MulterModule.register
    static fields = FileFieldsInterceptor
    static array = FilesInterceptor
    static single = FileInterceptor

    static diskStorage: multer.StorageEngine = multer.diskStorage({
        destination(_: Request, file: Express.Multer.File, done: any) {
            let linux: string = `${process.env.IMG_DIR}`
            let window: string = process.env.TEMP || ''

            if (!file) {
                done(new Error('Uploading file failed'), null)
            } else {
                if (process.platform === 'win32') {
                    if (fs.existsSync(window)) {
                        done(null, window)
                    } else {
                        done(new Error('No such file directory').message, null)
                    }
                } else {
                    if (fs.existsSync(linux)) {
                        done(null, linux)
                    } else {
                        done(new Error('No such file directory').message, null)
                    }
                }
            }
        },
        filename(_req: Request, file: Express.Multer.File, done: any) {
            if (!file) done(new Error('Get file upload failed'), null)
            const fileName: string = `${Date.now().toString()} - ${file.originalname}`
            done(null, fileName)
        }
    })

    static awsStorage: multer.StorageEngine = multerS3({
        s3: new aws.S3(),
        bucket: process.env.AWS_BUCKET_NAME,
        contentType: multerS3.AUTO_CONTENT_TYPE,
        serverSideEncryption: 'AES256',
        metadata(_req: Request, file: Express.Multer.File, done: any) {
            if (!file) done(new Error('Get file upload failed'), null)
            const readFile: InstanceType<typeof stream.Readable> = new stream.Readable({
                read() {
                    return true
                }
            })
            readFile
                .pipe(fs.createWriteStream(`${process.env.IMG_DIR}/${Date.now().toString()}-${file.originalname}`))
                .on('finish', Promise.resolve)
                .on('error', Promise.reject)

            done(null, file)
        },
        key(_req: Request, file: Express.Multer.File, done: any) {
            done(null, `${Date.now().toString()}-${file.originalname}`)
        }
    })

    static fileFilter(_req: Request, file: Express.Multer.File, done: any) {
        if (!mimeTypeSupport(file.mimetype)) throw new TypeError('mimetype not supported')
        if (file.size >= 5242880) throw new TypeError('maximum file or image size must be 5 MB or under 5 MB')

        const fileName: string = `${Date.now().toString()} - ${file.originalname}`
        done(null, fileName)
    }
}