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[C#]How to retrieve LONGBLOB image from mysql in picturebox

Posted on 2016-09-29
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Last Modified: 2016-11-09
Hello,
I need to retrieve the longblob of a picture from mysql.
So first I insert it in the database with this:
MemoryStream ms = new MemoryStream();
                  //  PIC_Image.Image.Save(ms, PIC_Image.Image.RawFormat);
                    byte[] img = ms.ToArray();
 
                    string q = "insert into tb_produits (Image) values('" + img+ "')";

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Here is to retrieve the picture :
public static Bitmap ByteToImage(byte[] blob)
        {
            MemoryStream mStream = new MemoryStream();
            byte[] pData = blob;
            mStream.Write(pData, 0, Convert.ToInt32(pData.Length));
            Bitmap bm = new Bitmap(mStream, false);
            mStream.Dispose();
            return bm;
 
        }
 
 MySqlDataAdapter sda = new MySqlDataAdapter("SELECT * FROM tb_produits WHERE Designation='" + Designation + "'and Reference='" + Reference + "'", MyConnexion);
            DataTable dt = new DataTable();
 
            sda.Fill(dt);
            if (dt.Rows.Count == 1)
            {
                byte[] img = (byte[])dt.Rows[0]["Image"];
 
             
 
              
                PIC_Image.Image = ByteToImage(img);
            }

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I tried to retrieve but I got an error:
Parameter is not valid in this line " Bitmap bm = new Bitmap(mStream, false);"
0
Comment
Question by:SniperCode Sheva
  • 4
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9 Comments
 
LVL 45

Expert Comment

by:AndyAinscow
ID: 41822004
MemoryStream ms = new MemoryStream();
                  //  PIC_Image.Image.Save(ms, PIC_Image.Image.RawFormat);
                    byte[] img = ms.ToArray();
                    string q = "insert into tb_produits (Image) values('" + img+ "')";

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img is empty when you save it.  Hence your failure when you retrieve it.
0
 
LVL 1

Author Comment

by:SniperCode Sheva
ID: 41822033
It is not empty because in the database I see this : "[BLOB - 13 o]"
0
 
LVL 45

Expert Comment

by:AndyAinscow
ID: 41822144
This is your code:

new memory stream with nothing in it
MemoryStream ms = new MemoryStream();
                 
convert empty memory stream to empty byte array = no picure
byte[] img = ms.ToArray();

insert the empty byte array into the database
string q = "insert into tb_produits (Image) values('" + img+ "')";
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LVL 1

Author Comment

by:SniperCode Sheva
ID: 41822148
I forgot to edit this PIC_Image.Image.Save(ms, PIC_Image.Image.RawFormat);
0
 
LVL 45

Expert Comment

by:AndyAinscow
ID: 41822155
You had that in your code but commented out.  Please post your code that you use - without editing it
0
 
LVL 1

Author Comment

by:SniperCode Sheva
ID: 41822185
 MemoryStream ms = new MemoryStream();
                   PIC_Image.Image.Save(ms, PIC_Image.Image.RawFormat);
                   
                    byte[] img = ms.GetBuffer();
string q = "insert into tb_produits (Image) values('" + img+ "')";

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Image is of type Blob
0
 
LVL 45

Expert Comment

by:AndyAinscow
ID: 41822230
OK.  Lets try to see which bits of code work by modifying things slightly.

 MemoryStream ms = new MemoryStream();
                   PIC_Image.Image.Save(ms, PIC_Image.Image.RawFormat);
                   
                    byte[] img = ms.GetBuffer();

See if this line here works - converting your image to a blob and then back to the bitmap without using the database.
Bitmap bm = ByteToImage(img);


string q = "insert into tb_produits (Image) values('" + img+ "')";
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LVL 1

Accepted Solution

by:
SniperCode Sheva earned 0 total points
ID: 41823358
Hello, I found a solution to add the picture with your code now I need to check if the image is empty in the database ....
Here is what I did;
try
            {

                
                MySqlDataAdapter sda = new MySqlDataAdapter("SELECT * FROM tb_produits", MyConnexion);
                sda.Fill(dt);

              
              
                    
                        object o = (byte[])dt.Rows[0]["Image"];
                        if (o is System.DBNull)
                    {
                        PIC_Image.Image = Properties.Resources.Aa;
                        PIC_Image.SizeMode = PictureBoxSizeMode.Zoom;
                        PIC_Image.BorderStyle = BorderStyle.FixedSingle;
                        PIC_Image.Refresh();
                    }
                    else
                    {
                        byte[] img = (byte[])dt.Rows[count]["Image"];

                        MemoryStream ms = new MemoryStream(img);
                        PIC_Image.Image = Bitmap.FromStream(ms);
                        PIC_Image.SizeMode = PictureBoxSizeMode.Zoom;
                        PIC_Image.BorderStyle = BorderStyle.FixedSingle;
                        PIC_Image.Refresh();

                    }
}

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But the picture that I gave when it si empty doesn't appear...
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