Download Multiple Uploaded Files - asp.net-mvc

Question

I uploaded multiple files as bytes into database table and how to download files as zip now? My code as below:
View:
#using (Html.BeginForm(Html.BeginForm("upload", "Home", FormMethod.Post, new { #id = "form", enctype = "multipart/form-data" })))
{
<input type="file" multiple="multiple" name="files" id="files" />
<div class="form-group">
<div class="col-md-offset-2 col-md-10">
<input type="submit" value="Submit" class="btn btn-default" />
</div>
</div>
}
controller:
public FileContentResult GetFile(int id)
{
SqlDataReader rdr; byte[] fileContent = null;
string mimeType = ""; string fileName = "";
string constr = WebConfigurationManager.ConnectionStrings["DbContextModel"].ConnectionString;
using (SqlConnection con = new SqlConnection(constr))
{
var qry = "SELECT * FROM myTable WHERE ID = #ID";
var cmd = new SqlCommand(qry, con);
cmd.Parameters.AddWithValue("#ID", id);
con.Open();
rdr = cmd.ExecuteReader();
if (rdr.HasRows)
{
rdr.Read();
fileContent = (byte[])rdr["Attachments"];
}
}
return File(fileContent, "application/zip", "download.zip");
}
Model:
public partial class myTable
{
public int id {get;set;}
public byte[] Attachments { get; set; }
}
The download.zip file cannot be opened. "The compressed zipped folder is invalid". Please advise. Thanks in advance.
upload function:
...
byte[] bytes = new byte[] { 0x20, 0x20, 0x20, 0x20, 0x20, 0x20 };
MemoryStream target = new MemoryStream();
foreach (var file in files)
{
if (file.ContentLength > 0)
{
file.InputStream.CopyTo(target);
bytes = target.ToArray();
}
}

Answer 1

Appending the data for each uploaded file into a single stream doesn't create a valid zip file. You need to generate a valid zip file to store in the database.
For example:
byte[] bytes;
var target = new MemoryStream();
using (var zip = new ZipArchive(target, ZipArchiveMode.Create, true))
{
foreach (var file in files)
{
string name = Path.GetFileName(file.FileName);
ZipArchiveEntry entry = zip.CreateEntry(name);
using (Stream entryStream = entry.Open())
{
file.InputStream.CopyTo(entryStream);
}
}
bytes = target.ToArray();
}
ZipArchive Class