C＃：文件下载为字节数组后文件损坏

Question

I have a project in which I store documents as blobs in a MySQL database, and download them as byte arrays using C#:

public static byte[] GetFile(string fileName)
{
        conn.Open();
        MySqlCommand cmd = conn.CreateCommand();
        cmd.CommandText = ...
        using (MySqlDataReader reader = cmd.ExecuteReader())
        {
            reader.Read();
            if (reader.HasRows)
            {
                 return Util.ObjectToByteArray(reader["Content"]);
            }
          ...
}

...

public static byte[] ObjectToByteArray(object obj)
{
    BinaryFormatter bf = new BinaryFormatter();
    using (var ms = new MemoryStream())
    {
        bf.Serialize(ms, obj);
        return ms.ToArray();
    }
}

I upload the files like this:

byte[] newFile = File.ReadAllBytes(fileName);

and download like this:

File.WriteAllBytes(path + "\\" + selectedFileName, 
                   DocumentTable.GetFile(selectedFileName));

but when I download the files, they are corrupted and cannot be opened (for example Excel files, some other types can be opened). The extension of the downloaded file seems to be correct, but I am getting the message that "the file extension or file format are not valid".

Answer 1

I recommend using the GetStream() override of the data reader;

content = reader.GetStream(1);

and simply returning the stream object to your File writer.