Display pdf file from postgresql to a datagridview using c#

Jes Sie

6y876General

Hello again everyone,

How can I retrieve and display the uploaded pdf/doc file from PostgreSQL to a datagridview in WinForms using C#?

This is my first time using a PostgreSQL. Thanks, everyone.

5 Replies

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Laxmidhar Sahoo6y ago
Do not use reader .Use dataset . if use reader then use it in while may access data
if (rdr.Read())
{
while(rdr.Reead())
{
data_file = (byte[])rdr[0];

}
}
Jes Sie6y ago
this is what I did but it says "parameter is not valid". Refer to code snippet below;
private void DisplayFile()
        {
            byte[] data_file = null;

            using (NpgsqlConnection con = ClassConnection.GetDbCon())
            {
                using (NpgsqlCommand cmd = new NpgsqlCommand("SELECT data_file FROM public.uploaded_file WHERE id = @id;", con))
                {
                    cmd.CommandType = CommandType.Text;
                    con.Open();
                    cmd.Parameters.AddWithValue("@id", NpgsqlTypes.NpgsqlDbType.Integer).Value = 2;
                    NpgsqlDataReader rdr = cmd.ExecuteReader();
                    if (rdr.Read())
                    {
                        data_file = (byte[])rdr[0];
                    }
                    rdr.Close();
                    if (data_file != null)
                    {
                        using (MemoryStream productImageStream = new MemoryStream(data_file))
                        {
                            ImageConverter imageConverter = new ImageConverter();
                            pictureBox1.Image = imageConverter.ConvertFrom(data_file) as Image;
                        }
                    }
                }
            }
        }
How do I use your code?
Laxmidhar Sahoo6y ago
1. Hi
3. You have to customize a gridview column as pdf which is derived from DataGridViewImageColumn
6. or
8. Display as image
11. public Image byteArrayToImage(byte[] byteArrayIn)
12. {
13. MemoryStream ms = new MemoryStream(byteArrayIn);
14. Image returnImage = Image.FromStream(ms);
15. return returnImage;
16. }
17. void dataGridView_CellFormatting(object sender, DataGridViewCellFormattingEventArgs e)
18. {
19. // 2 - Salt, 3 - SecurePassword
20. if (e.ColumnIndex == 2 )
21. {
22. if (e.Value != null)
23. {
24. byte[] array = (byte[])e.Value;
25. e.Value = byteArrayToImage(array);
26. e.FormattingApplied = true;
27. }
28. else
29. e.FormattingApplied = false;
30. }
31. }

Jes Sie6y ago

Hello Lax, below is what I did:

private void btnFileUpload_Click(object sender, EventArgs e)
{
DialogResult result = openFileDialog1.ShowDialog();
if (result == DialogResult.OK)
{
string extension = Path.GetExtension(openFileDialog1.FileName);
string fname = Path.GetFileName(openFileDialog1.FileName);
switch (extension)
{
case ".doc":
case ".docx":
case ".pdf":
using(FileStream fs = new FileStream("D:\\Saved Images\\" + fname, FileMode.Open, FileAccess.Read))
{
using (BinaryReader pgReader = new BinaryReader(new BufferedStream(fs)))
{
byte[] ImgByteA = pgReader.ReadBytes(Convert.ToInt32(fs.Length));
using (NpgsqlConnection con = ClassConnection.GetDbCon())
{
string query = "INSERT INTO public.uploaded_file(file_name, content_type, data_file) VALUES(@file_name, @content_type, @data_file); ";
using (var cmd = new NpgsqlCommand(query, con))
{
cmd.CommandType = CommandType.Text;
cmd.Parameters.AddWithValue("@file_name", fname);
cmd.Parameters.AddWithValue("@content_type", extension);
cmd.Parameters.AddWithValue("@data_file", NpgsqlTypes.NpgsqlDbType.Bytea).Value = ImgByteA;
con.Open();
cmd.ExecuteNonQuery();
}
}
}
}
break;
}
}
}

Laxmidhar Sahoo6y ago

How stored the file in postGreSQL . I mean you srored the file path of the pdf or in byte array

or with some other format

Thanks and Regards