Displaying Files of Unknown Types Stored in SQL Server Using C# WPF

Question

I am developing a C# WPF application using .NET 6 in Visual Studio 2022, with a SQL Server 2008 R2 database. My database contains a table GRADE_CUST_GRP with a column GCPS of type image, where files of various types are stored without any file extension information. I am looking for a way to retrieve and open these files in a WPF application, similar to how "SQL Image Viewer" dynamically displays content based on the file's actual type (e.g., displaying an image for picture files, or opening a document for PDF/text files), without prior knowledge of the file type. The challenge is to detect the file type from the byte content and then display or open the file appropriately in the WPF application. I am open to using third-party libraries or any .NET functionality that could help achieve this. However, attempts to use the MimeType class for recognizing the file type were unsuccessful, as it did not recognize the file type correctly. Here is the SQL definition for the relevant part of the table:

CREATE TABLE [dbo].[GRADE_CUST_GRP]
(
    [GCGRPID] [int] NOT NULL,
    [GCPS] [image] NULL
)

How can I achieve the functionality of opening and viewing files directly from the database in my WPF application, regardless of their type, as "SQL Image Viewer" does? Any suggestions for libraries or approaches for detecting file types and handling them appropriately in WPF would be greatly appreciated, especially considering the limitations I encountered with the MimeType class and the diverse file types, including OLE Object packages. (From MS Access) Please provide code examples or guidance on how to implement this feature.

Answer 1

Maybe it is possible to load the database contents to a byte array, then try to make a BitmapImage object, which will check if the contents is an image:

byte[] bytes = ... load from GCPS column ...

try
{
    var bi = new BitmapImage( );
    using( var ms = new MemoryStream( bytes ) )
    {
        bi.BeginInit( );
        bi.CacheOption = BitmapCacheOption.OnLoad;
        bi.CreateOptions = BitmapCreateOptions.PreservePixelFormat;
        bi.StreamSource = ms;
        bi.EndInit( );
    }

    // display the image using an <Image> control
    image1.Source = bi;
}
catch( Exception exc )
{
    // The image cannot be displayed
    // TODO: filter the exceptions
}

Answer 2

Microsoft recommends varbinary(MAX) over Image type. Using varbinary(MAX) your data is returned as a byte array. Add a column to specify the image type but in most cases you should be able to create a Image to display. Helper extension

public static class Extensions
{
    public static Image BytesToImage(this byte[] bytes)
    {
        var imageData = bytes;
        using var ms = new MemoryStream(imageData, 0, imageData.Length);
        ms.Write(imageData, 0, imageData.Length);
        return Image.FromStream(ms, true); 
    }
}

EDIT: How to import an image from to a varbinary(MAX) column. Replace ConnectionString() with your connection string.

public (bool success, Exception exception) InsertFileSimple(string filePath, string fileName, ref int newIdentifier)
{
    byte[] fileByes;

    using (var stream = new FileStream(filePath, FileMode.Open, FileAccess.Read))
    {
        using (var reader = new BinaryReader(stream))
        {
            fileByes = reader.ReadBytes((int)stream.Length);
        }
    }

    using var cn = new SqlConnection() { ConnectionString = ConnectionString() };
    using var cmd = new SqlCommand()
    {
        Connection = cn,
        CommandText =
            """
            INSERT INTO Table1 (FileContents,FileName) VALUES (@FileContents,@FileName);
            SELECT CAST(scope_identity() AS int);
            """
    };

    cmd.Parameters.Add("@FileContents", SqlDbType.VarBinary, fileByes.Length).Value = fileByes;
    cmd.Parameters.Add(new SqlParameter("@FileName", SqlDbType.Text)).Value = fileName;

    try
    {
        cn.Open();

        newIdentifier = Convert.ToInt32(cmd.ExecuteScalar());
        return (true,null);

    }
    catch (Exception ex)
    {
        return (false, ex);
    }
}

Answer 3

with a SQL Server 2008 R2

That version is out-of-support.

of type image

The data type "image" is deprecated since version 2005, better use varbinary(max)

The challenge is to detect the file type

If you don't store the information = file type (MIME), then it is a challenge.

Answer 4

this is usually referred to as file magic number detection. here is a GitHub collection:

https://github.com/topics/file-type-detection?l=c%23