使用nestjs和multer上传文件

Question

由于nestjs是一个快速应用程序，因此可以使用任何库来处理使用嵌套的上传，并且由于它提供了Midlewares，因此也可以使用multer。我的问题是：使用nestjs处理文件上传的最佳方法是什么？

Answer 1

正如@Kamyl在https://github.com/nestjs/nest/issues/262问题上所知，由于v4.6.0可以使用公共文件拦截器使用multer上传文件到nestjs。

import { ... , UseInterceptors, FileInterceptor, UploadedFile } from '@nestjs/common'

... 

@UseInterceptors(FileInterceptor('file'))
async upload( @UploadedFile() file) {
  console.log(file)
}

这样变量file将有一个buffer

---

Using Multer options

它还需要字段名称作为第一个参数，然后是具有Multer选项的数组

import { ... , UseInterceptors, FileInterceptor, UploadedFile } from '@nestjs/common'
import { diskStorage } from 'multer'
import { extname } from 'path'

...

@UseInterceptors(FileInterceptor('file', {
  storage: diskStorage({
    destination: './uploads'
    , filename: (req, file, cb) => {
      // Generating a 32 random chars long string
      const randomName = Array(32).fill(null).map(() => (Math.round(Math.random() * 16)).toString(16)).join('')
      //Calling the callback passing the random name generated with the original extension name
      cb(null, `${randomName}${extname(file.originalname)}`)
    }
  })
}))
async upload( @UploadedFile() file) {
  console.log(file)
}

这样变量file将有filename，destination和path。

来自destination的diskStorage param也可以是一个函数，参数和期望回调与filename相同。通过传递diskStorage文件将自动保存到目的地通知给出的文件名。

使用@UploadedFiles和FilesInterceptor（复数）也可以处理多个文件

Answer 2

更简洁的方法是将配置提取到单独的文件，然后在拦截器方法中调用它

import { extname } from 'path';
import { existsSync, mkdirSync } from 'fs';
import { diskStorage } from 'multer';
import { v4 as uuid } from 'uuid';
import { HttpException, HttpStatus } from '@nestjs/common';

// Multer configuration
export const multerConfig = {
    dest: process.env.UPLOAD_LOCATION,
};

// Multer upload options
export const multerOptions = {
    // Enable file size limits
    limits: {
        fileSize: +process.env.MAX_FILE_SIZE,
    },
    // Check the mimetypes to allow for upload
    fileFilter: (req: any, file: any, cb: any) => {
        if (file.mimetype.match(/\/(jpg|jpeg|png|gif)$/)) {
            // Allow storage of file
            cb(null, true);
        } else {
            // Reject file
            cb(new HttpException(`Unsupported file type ${extname(file.originalname)}`, HttpStatus.BAD_REQUEST), false);
        }
    },
    // Storage properties
    storage: diskStorage({
        // Destination storage path details
        destination: (req: any, file: any, cb: any) => {
            const uploadPath = multerConfig.dest;
            // Create folder if doesn't exist
            if (!existsSync(uploadPath)) {
                mkdirSync(uploadPath);
            }
            cb(null, uploadPath);
        },
        // File modification details
        filename: (req: any, file: any, cb: any) => {
            // Calling the callback passing the random name generated with the original extension name
            cb(null, `${uuid()}${extname(file.originalname)}`);
        },
    }),
};

然后像拦截器一样在拦截器下调用它

import { ... , UseInterceptors, FileInterceptor, UploadedFile } from '@nestjs/common'
import { diskStorage } from 'multer'
import { extname } from 'path'
import { multerOptions } from 'src/config/multer.config';
...

@Post('/action/upload')
@UseInterceptors(FileInterceptor('file', multerOptions))
async upload( @UploadedFile() file) {
  console.log(file)
}

Answer 3

一种简单的方法是使用控制器。您需要定义一个上传控制器并将其添加到您的app.module中，这是一个控制器应该是什么（后端）的示例：

@Controller()
export class Uploader {
  @Post('sampleName')
  @UseInterceptors(FileInterceptor('file'))
  uploadFile(@UploadedFile() file) {
  // file name selection 
    const path = `desired path`;
    const writeStream = fs.createWriteStream(path);  
    writeStream.write(file.buffer);
    writeStream.end();
    return {
      result: [res],
    };
  }
}

并通过前端fetch调用您的控制器：

    fetch('controller address', {
          method: 'POST',
          body: data,
        })
          .then((response) => response.json())
          .then((success) => {
            // What to do when succeed 
});
          })
          .catch((error) => console.log('Error in uploading file: ', error));