Reading and Saving Images from/to a Database using C#

"Mahesh Chand is a founder of C# Corner";

userDes += "Author: 1. A Programmer's Guide to ADO.NET;";

userDea += ", 2. Applied ADO.NET.";

//Create a new row

DataRow row = ds.Tables ["Users"].NewRow();

row["UserName] ="Mahesh Chand";

row["UserEmail"]= [email protected];

row["UserDescription"] = userDes;

row["UserPhoto"] = rawData;

//Add the row to the collection

ds.Tables ["Users"].Rows.Add (row);

//Save changes to the database

adapter.Update (ds, "Users");

//Clean up connection

if(conn!=null)

{

if (con.State == ConnectionState.Open)

conn.Close();

//Dispose of connection

conn.Dispose();

}

MessageBox.Show ("Image Saved");

}

Once the data has been saved, the next step is to read data from the database table, save it as a bitmap again, and view the bitmap on the form. We can view an image using the Graphics.DrawImage method or using a picture box. Our example uses a picture box.

The code for reading binary data is shown in Listing 15.11. We open a connection, create a data adapter, fill a data set, and get the first row of the Users table. If you want to read all the images, you may want to modify your application or loop through all the rows. Once a row has been read, we retrieve the data stored in the UserPhoto column in a stream and save it as a bitmap file. Later we view that bitmap file in a picture box by setting its Image property to the file name.

Listing 15.11: Reading images from a database

private void ReadImageBtn_Click(object sender, System.EventArgs e)

{

//Construct a SQL string and a connection object

string sql = "SELECT * FROM Users";

OleDbConnection conn = new OleDbConnection();

conn.ConnectionString = connectionString;

//Open the connection

if (conn.State != ConnectionState.Open)

conn.Open();

//Create a data adapter and data set

OleDbDataAdapter adapter =

new OleDbDataAdapter(sql, conn);

OleDbCommandBuilder cmdBuilder =

new OleDbCommandBuilder(adapter);

DataSet ds = new DataSet("Users");

adapter.MissingSchemaAction =

MissingSchemaAction.AddWithKey;

//Fill the data adapter

adapter.Fill(ds, "Users");

//Get the first row of the table

DataRow row = ds.Tables["Users"].Rows[0];

//Read data in a stream

byte[] rawData = new byte[0];

rawData = (byte[])row["UserPhoto"];

int len = new int();

len = rawData.GetUpperBound(0);

//Save rawData as a bitmap

FileStream fs = new FileStream

(savedImageName, FileMode.OpenOrCreate,

FileAccess.Write);

fs.Write(rawData, 0, len);

//Close the stream

fs.Close();

//View the image in a pciture box

curImage = Image.FromFile(savedImageName);

pictureBox1.Image = curImage;

//Clean up connection

if (conn != null)

{

if (conn.State == ConnectionState.Open)

conn.Close();

//Dispose of connection

conn.Dispose();

}

}

To see the program in action, we select the MyPhoto.bmp file by using the Browse Image button, and we click the Save Image button. When we open the database, we see that a new record has been added to the Users table. When we click on the Read Image button, a new ImageFromDb.bmp file is added to the current folder. The output is shown in figure 15.9.



Figure 15.9: Displaying a bitmap after reading data from a database