In this article I will explain with an example, how to upload files, save (insert) file to Database Table, retrieve (display) files in HTML Grid and download the files from Database Table in ASP.Net Core MVC.
Note: For beginners in ASP.Net Core (.Net Core 7), please refer my article ASP.Net Core 7: Hello World Tutorial with Sample Program example.
 
 

Database

I have made use of the following table tblFiles with the schema as follows.
ASP.Net Core MVC: Upload Files, Save (Insert) file to Database and Download Files
 
Note: You can download the database table SQL by clicking the download link below.
          Download SQL file
 
 

Namespaces

You will need to import the following namespace.
using System.Data.SqlClient;
 
 

Model

The Model class consists of following properties.
public class FileModel
{
    public int Id { get; set; }
    public string Name { get; set; }
    public string ContentType { get; set; }
    public byte[] Data { get; set; }
}
 
 

Controller

The Controller consists of following Action methods.

Action method for handling GET operation

Inside the Action method, the GetFiles method is called inside which the records from the tblFiles table are fetched using ExecuteReader method and stored into a Generic List collection of FileModel class object which is ultimately returned.
Note: For more details on ExecuteReader method, please refer my article Using SqlCommand ExecuteReader Example in ASP.Net with C# and VB.Net.
 
Finally, the Generic List collection of FileModel class object is returned to the View.
 

Action method for handling POST operation for uploading Files

This Action method gets called when a File is selected and the Upload Button is clicked.
This Action method accepts the IFormFile parameter.
Note: In case the IFormFile parameter is appearing NULL, please refer the article, ASP.Net Core: IFormFile always returns NULL.
 
The uploaded file is copied to MemoryStream class object and converted to BYTE Array and finally, is inserted into the database table along with File Name and Content Type.
After successful insertion of the File, RedirectToAction is called which redirects to the Index Action method.
 

Action method for handling POST operation for downloading Files

When the Download Link inside the HTML Table (Grid) is clicked, the Id of the particular file is sent to this Action method and using the File ID, the File’s binary data is fetched from the database.
Finally, the File is downloaded using the File function which accepts the Binary data, Content Type and Name of the file.
public class HomeController : Controller
{
    private IConfiguration Configuration;
 
    public HomeController(IConfiguration _configuration)
    {
        this.Configuration = _configuration;
    }
 
    public IActionResult Index()
    {
        return View(this.GetFiles());
    }
 
    [HttpPost]
    public IActionResult UploadFile(IFormFile postedFile)
    {
        string fileName = Path.GetFileName(postedFile.FileName);
        string contentType = postedFile.ContentType;
        using (MemoryStream ms = new MemoryStream())
        {
            postedFile.CopyTo(ms);
            string constr = this.Configuration.GetSection("ConnectionStrings")["MyConn"];
            using (SqlConnection con = new SqlConnection(constr))
            {
                string sql = "INSERT INTO tblFiles VALUES (@Name, @ContentType, @Data)";
                using (SqlCommand cmd = new SqlCommand(sql, con))
                {
                    cmd.Parameters.AddWithValue("@Name", fileName);
                    cmd.Parameters.AddWithValue("@ContentType", contentType);
                    cmd.Parameters.AddWithValue("@Data", ms.ToArray());
                    con.Open();
                    cmd.ExecuteNonQuery();
                    con.Close();
                }
            }
        }
 
        return RedirectToAction("Index");
    }
 
    [HttpPost]
    public IActionResult DownloadFile(int fileId)
    {
        byte[] bytes;
        string fileName, contentType;
        string constr = this.Configuration.GetSection("ConnectionStrings")["MyConn"];
        string sql = "SELECT Name, Data, ContentType FROM tblFiles WHERE Id=@Id";
        using (SqlConnection con = new SqlConnection(constr))
        {
            using (SqlCommand cmd = new SqlCommand(sql, con))
            {
                cmd.Parameters.AddWithValue("@Id", fileId);
                con.Open();
                using (SqlDataReader sdr = cmd.ExecuteReader())
                {
                    sdr.Read();
                    bytes = (byte[])sdr["Data"];
                    contentType = sdr["ContentType"].ToString();
                    fileName = sdr["Name"].ToString();
                }
                con.Close();
            }
        }
 
        return File(bytes, contentType, fileName);
    }
 
    private List<FileModel> GetFiles()
    {
        List<FileModel> files = new List<FileModel>();
        string constr = this.Configuration.GetSection("ConnectionStrings")["MyConn"];
        string sql = "SELECT Id, Name FROM tblFiles";
        using (SqlConnection con = new SqlConnection(constr))
        {
            using (SqlCommand cmd = new SqlCommand(sql, con))
            {
                con.Open();
                using (SqlDataReader sdr = cmd.ExecuteReader())
                {
                    while (sdr.Read())
                    {
                        files.Add(new FileModel
                        {
                            Id = Convert.ToInt32(sdr["Id"]),
                            Name = sdr["Name"].ToString()
                        });
                    }
                }
                con.Close();
            }
        }
        return files;
    }
}
 
 

View

HTML Markup

Inside the View, in the very first line the FileModel class is declared as IEnumerable which specifies that it will be available as a Collection.
The View consists of two HTML Forms which have been created using the following Tag Helpers attributes.
asp-action – Name of the Action.
asp-controller – Name of the Controller. In this case the name is Home.
method – It specifies the Form Method i.e. GET or POST. In this case it will be set to POST.
Inside the View, following script file is inherited.
1. jquery.min.js
 

Uploading the File

This Form has been specified with enctype=“multipart/form-data” attribute as it is necessary for File Upload operation.
The Form consists of an HTML FileUpload element and a Submit Button.
When the Submit Button is clicked, the UploadFile Action method for handling POST operation will be called.
 

Downloading the File

The Form consists of an HTML HiddenField and a Hidden Submit Button.
When any Download Link inside the HTML Table (Grid) is clicked, then the DownloadFile JavaScript function is called, which sets the FileId into the HiddenField and calls the click event of the Submit Button which ultimately submits the Form.
When the Form is submitted, the DownloadFile Action method is called, which performs the File download operation.
 

Displaying the Files

For displaying the files, an HTML Table is used. A FOR EACH loop will be executed over the Model which will generate the HTML Table rows with the File records.
@addTagHelper*, Microsoft.AspNetCore.Mvc.TagHelpers
@model IEnumerable<Upload_File_Database_MVC_Core.Models.FileModel>
@{
    Layout = null;
}
 
<!DOCTYPE html>
 
<html>
<head>
    <meta name="viewport" content="width=device-width" />
    <title>Index</title>
    <script type="text/javascript" src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.7.1/jquery.min.js"></script>
    <script type="text/javascript">
        function DownloadFile(fileId) {
            $("#hfFileId").val(fileId);
            $("#btnDownload")[0].click();
        };
    </script>
</head>
<body>
    <form method="post" enctype="multipart/form-data" asp-controller="Home" asp-action="UploadFile">
        <input type="file" name="postedFile" />
        <input type="submit" id="btnUpload" value="Upload" />
    </form>
    <form method="post" asp-controller="Home" asp-action="DownloadFile">
        <input type="hidden" id="hfFileId" name="FileId" />
        <input type="submit" id="btnDownload" value="Download" style="display:none" />
    </form>
    <hr />
    <table id="tblFiles" cellpadding="0" cellspacing="0">
        <tr>
            <th style="width:50px">File ID</th>
            <th style="width:120px">File Name</th>
            <th style="width:80px">Download</th>
        </tr>
        @foreach (var file in Model)
        {
            <tr>
                <td>@file.Id</td>
                <td>@file.Name</td>
                <td><a href="javascript:;" onclick="DownloadFile(@file.Id)">Download</a></td>
            </tr>
        }
    </table>
</body>
</html>
 
 

Screenshot

ASP.Net Core MVC: Upload Files, Save (Insert) file to Database and Download Files
 
 

Downloads

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