NestJS: Array of Files – A Comprehensive Guide
Managing files in a NestJS application can be a complex task, especially when dealing with an array of files. Whether you’re handling file uploads, storing files, or serving them to users, understanding how to work with an array of files in NestJS is crucial. In this detailed guide, we’ll explore various aspects of managing files in a NestJS application, from file upload to serving files. Let’s dive in!
Understanding the File Upload Process
Before we delve into the specifics of handling an array of files in NestJS, it’s essential to understand the file upload process. Typically, file uploads involve the following steps:
-
Client-side: The user selects a file or files to upload.
-
Server-side: The server receives the file(s) and processes them.
-
Storage: The server stores the file(s) in a designated location.
-
Serving: The server serves the file(s) to the user when requested.
Now that we have a basic understanding of the file upload process, let’s explore how to handle an array of files in NestJS.
Setting Up a File Upload Endpoint
One of the first steps in handling an array of files in NestJS is setting up a file upload endpoint. This can be done using the `@nestjs/common` and `@nestjs/platform-express` packages. Here’s an example of how to create a simple file upload endpoint:
import { Controller, Post, UseInterceptors, UploadedFile } from '@nestjs/common';import { FileInterceptor } from '@nestjs/platform-express';import { Express } from 'express';@Controller('upload')export class UploadController { constructor(private readonly express: Express) {} @Post() @UseInterceptors(FileInterceptor('file')) uploadFile(@UploadedFile() file: Express.Multer.File) { // Process the file here }}In this example, we’ve created a `UploadController` with a `uploadFile` method. The `FileInterceptor` is used to handle the file upload, and the `@UploadedFile()` decorator is used to extract the uploaded file from the request.
Storing Files in an Array
Once you have the file upload endpoint set up, you’ll need to store the files in an array. This can be done in several ways, depending on your application’s requirements. Here’s an example of how to store files in an array using a simple in-memory array:
import { Injectable } from '@nestjs/common';@Injectable()export class FileService { private files: Express.Multer.File[] = []; storeFile(file: Express.Multer.File) { this.files.push(file); } getFiles() { return this.files; }}In this example, we’ve created a `FileService` class with a `files` array to store the uploaded files. The `storeFile` method adds a file to the array, and the `getFiles` method returns the array of files.
Handling Multiple Files
When dealing with an array of files, it’s essential to handle multiple files correctly. In the previous example, we stored a single file in the array. However, you can modify the `uploadFile` method to handle multiple files:
import { Controller, Post, UseInterceptors,UploadedFiles } from '@nestjs/common';import { FileInterceptor } from '@nestjs/platform-express';@Controller('upload')export class UploadController { @Post() @UseInterceptors(FileInterceptor('files')) uploadFiles(@UploadedFiles() files: Express.Multer.File[]) { // Process the files here }}In this updated example, we’ve changed the `FileInterceptor` from `’file’` to `’files’`, allowing us to handle multiple files. The `@UploadedFiles()` decorator now returns an array of files, which we can process as needed.
Serving Files from an Array
Once you’ve stored the files in an array, you may need to serve them to users. NestJS provides several ways to serve files, including the `FileInterceptor` and the `ServeStaticModule`. Here’s an example of how to serve files from an array using the `ServeStaticModule`:
import { Module, ServeStaticModule } from '@nestjs/common';import { FileInterceptor } from
