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Upload Single And Multiple Files Using The .NET Core 6 Web API

Introduction

We are going to discuss single and multiple file uploads with the help of the IFormFile Interface and others that are provided by .NET and step-b. y-step i.ag .NET Core 6 Web API.

  • .NET provides an IFormFile interface that represents transmitted files in an HTTP request.
  •  Also, it provides many properties like ContentDisposition, ContentType, FileName, Headers, Name, and Length.
  •  IFormFile also provides many methods, like copying the request stream content, opening the request stream for reading, and many more.

Prerequisites

  • .NET Core 6 SDK
  • Visual Studio 2022
  • SQL Server
  • Postman

Step By Step Implementation

Step 1. Create a new .NET Core Web API.

Solution Explorer

Step 2. Install the following NuGet Packages.

NuGet Package

Step 3. Create the following file entities.

FileDetails.cs

using System.ComponentModel.DataAnnotations;
using System.ComponentModel.DataAnnotations.Schema;

namespace FileUpload.Entities
{
    [Table("FileDetails")]
    public class FileDetails
    {
        [Key]
        [DatabaseGenerated(DatabaseGeneratedOption.Identity)]
        public int ID { get; set; }
        public string FileName { get; set; }
        public byte[] FileData { get; set; }
        public FileType FileType { get; set; }
    }
}

FileUploadModel

namespace FileUpload.Entities
{
    public class FileUploadModel
    {
        public IFormFile FileDetails { get; set; }
        public FileType FileType { get; set; }
    }
}

FileType

namespace FileUpload.Entities
{
    public enum FileType
    {
        PDF = 1,
        DOCX = 2
    }
}

Step 4. Next, the DbContextClass.cs class inside the Data folder.

using FileUpload.Entities;
using Microsoft.EntityFrameworkCore;

namespace FileUpload.Data
{
    public class DbContextClass : DbContext
    {
        protected readonly IConfiguration Configuration;

        public DbContextClass(IConfiguration configuration)
        {
            Configuration = configuration;
        }
        protected override void OnConfiguring(DbContextOptionsBuilder options)
        {
            options.UseSqlServer(Configuration.GetConnectionString("DefaultConnection"));
        }

        public DbSet<FileDetails> FileDetails { get; set; }
    }
}

Step 5. Create IFileService and FileService files.

IFileService

using FileUpload.Entities;

namespace FileUpload.Services
{
    public interface IFileService
    {
        public Task PostFileAsync(IFormFile fileData, FileType fileType);

        public Task PostMultiFileAsync(List<FileUploadModel> fileData);

        public Task DownloadFileById(int fileName);
    }
}

FileService

using FileUpload.Data;
using FileUpload.Entities;
using Microsoft.EntityFrameworkCore;

namespace FileUpload.Services
{
    public class FileService : IFileService
    {
        private readonly DbContextClass dbContextClass;

        public FileService(DbContextClass dbContextClass)
        {
            this.dbContextClass = dbContextClass;
        }

        public async Task PostFileAsync(IFormFile fileData, FileType fileType)
        {
            try
            {
                var fileDetails = new FileDetails()
                {
                    ID = 0,
                    FileName = fileData.FileName,
                    FileType = fileType,
                };

                using (var stream = new MemoryStream())
                {
                    fileData.CopyTo(stream);
                    fileDetails.FileData = stream.ToArray();
                }

                var result = dbContextClass.FileDetails.Add(fileDetails);
                await dbContextClass.SaveChangesAsync();
            }
            catch (Exception)
            {
                throw;
            }
        }

        public async Task PostMultiFileAsync(List<FileUploadModel> fileData)
        {
            try
            {
                foreach(FileUploadModel file in fileData)
                {
                    var fileDetails = new FileDetails()
                    {
                        ID = 0,
                        FileName = file.FileDetails.FileName,
                        FileType = file.FileType,
                    };

                    using (var stream = new MemoryStream())
                    {
                        file.FileDetails.CopyTo(stream);
                        fileDetails.FileData = stream.ToArray();
                    }

                    var result = dbContextClass.FileDetails.Add(fileDetails);
                }             
                await dbContextClass.SaveChangesAsync();
            }
            catch (Exception)
            {
                throw;
            }
        }

        public async Task DownloadFileById(int Id)
        {
            try
            {
                var file =  dbContextClass.FileDetails.Where(x => x.ID == Id).FirstOrDefaultAsync();

                var content = new System.IO.MemoryStream(file.Result.FileData);
                var path = Path.Combine(
                   Directory.GetCurrentDirectory(), "FileDownloaded",
                   file.Result.FileName);

                await CopyStream(content, path);
            }
            catch (Exception)
            {
                throw;
            }        
        }
 
        public async Task CopyStream(Stream stream, string downloadPath)
        {
            using (var fileStream = new FileStream(downloadPath, FileMode.Create, FileAccess.Write))
            {
               await stream.CopyToAsync(fileStream);
            }
        }
    }
}

Step 6. Create FilesController.cs inside the controller section.

using FileUpload.Entities;
using FileUpload.Services;
using Microsoft.AspNetCore.Http;
using Microsoft.AspNetCore.Mvc;

namespace FileUpload.Controllers
{
    [Route("api/[controller]")]
    [ApiController]
    public class FilesController : ControllerBase
    {
        private readonly IFileService _uploadService;

        public FilesController(IFileService uploadService)
        {
            _uploadService = uploadService;
        }

        /// <summary>
        /// Single File Upload
        /// </summary>
        /// <param name="file"></param>
        /// <returns></returns>
        [HttpPost("PostSingleFile")]
        public async Task<ActionResult> PostSingleFile([FromForm] FileUploadModel fileDetails)
        {
            if(fileDetails == null)
            {
                return BadRequest();
            }

            try
            {
                await _uploadService.PostFileAsync(fileDetails.FileDetails, fileDetails.FileType);
                return Ok();
            }
            catch (Exception)
            {
                throw;
            }         
        }

        /// <summary>
        /// Multiple File Upload
        /// </summary>
        /// <param name="file"></param>
        /// <returns></returns>
        [HttpPost("PostMultipleFile")]
        public async Task<ActionResult> PostMultipleFile([FromForm] List<FileUploadModel> fileDetails)
        {
            if (fileDetails == null)
            {
                return BadRequest();
            }

            try
            {
                await _uploadService.PostMultiFileAsync(fileDetails);
                return Ok();
            }
            catch (Exception)
            {
                throw;
            }
        }

        /// <summary>
        /// Download File
        /// </summary>
        /// <param name="file"></param>
        /// <returns></returns>
        [HttpGet("DownloadFile")]
        public async Task<ActionResult> DownloadFile(int id)
        {
            if (id < 1)
            {
                return BadRequest();
            }

            try
            {
                await _uploadService.DownloadFileById(id);
                return Ok();
            }
            catch (Exception)
            {
                throw;
            }
        }
    }
}

Step 7. Configure a few services in Program Class and inside the DI Container.

using FileUpload.Data;
using FileUpload.Services;
var builder = WebApplication.CreateBuilder(args);
// Add services to the container.
builder.Services.AddControllers();
// Learn more about configuring Swagger/OpenAPI at https://aka.ms/aspnetcore/swashbuckle
builder.Services.AddEndpointsApiExplorer();
builder.Services.AddSwaggerGen();
builder.Services.AddDbContext < DbContextClass > ();
builder.Services.AddScoped < IFileService, FileService > ();
var app = builder.Build();
// Configure the HTTP request pipeline.
if (app.Environment.IsDevelopment()) {
    app.UseSwagger();
    app.UseSwaggerUI();
}
app.UseAuthorization();
app.MapControllers();
app.Run();

Step 8. Create a new Database inside SQL Server and named it as FileUploadDemo.

Step 9. Next, create the FileDetails table using the following script.

USE [FileUploadDemo]
GO

/****** Object:  Table [dbo].[FileDetails]    Script Date: 10/1/2022 5:51:22 PM ******/
SET ANSI_NULLS ON
GO

SET QUOTED_IDENTIFIER ON
GO

CREATE TABLE [dbo].[FileDetails](
	[ID] [int] IDENTITY(1,1) NOT NULL,
	[FileName] [nvarchar](80) NOT NULL,
	[FileData] [varbinary](max) NOT NULL,
	[FileType] [int] NULL,
 CONSTRAINT [PK_FileDetails] PRIMARY KEY CLUSTERED 
(
	[ID] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON, OPTIMIZE_FOR_SEQUENTIAL_KEY = OFF) ON [PRIMARY]
) ON [PRIMARY] TEXTIMAGE_ON [PRIMARY]
GO

Step 10. Put database connection inside the appsettings.json file.

{
  "Logging": {
    "LogLevel": {
      "Default": "Information",
      "Microsoft.AspNetCore": "Warning"
    }
  },
  "AllowedHosts": "*",
  "ConnectionStrings": {
    "DefaultConnection": "Data Source=DESKTOP-****;;Initial Catalog=FileUploadDemo;User Id=sa;Password=database;"
  }
}

Step 11. Finally, we run the application.

Fileupload

Step 12. Now, we are going to upload a single file using swagger by providing the file and type of file based on the enum id.

Multi File Upload

Step 13. Also, for uploading multiple files, we use Postman. Here you can see we use an array index to send the file and their type, and it will be working fine.

POSTMAN

Step 14. Later on, based on file ID, we are able to download files on the local system at a specified path location.

FileUpload ID

Step 15. Here you can see the downloaded file at the specified location.

Location

Also, in the database, we can see whatever files we already uploaded using the above endpoints.

DB Endpoints

Conclusion

In this article, we discussed the single and multiple file upload using IFormFile and step-b. y-step i.ahat using .NET Core Web API and also read and save the files from the database to the specified location.

Happy Learning!


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