Introduction
This article explicate the method of inserting images and pictures into SQL Server database table and display it in an Asp.Net GridView control with the help of Handler.aspx.
Description
Have you seen any web application or website without images? No, you cannot. Images played a major role in web application development. Either it’s a static html website or an advanced RAD application, everything is build along with images. If your application is an E-Commerce based or Image Gallery portal, definitely you have to suffer lot on saving the images in different location with different sizes and types. And it’s not an easiest job to manage those unwanted and outdated images to be removed from your file server, then making backup of those images from one server location to another location. So it is clearly time consuming and hectic.
To make your task easier, this article explains you the methods of storing the images into data source. There are many advantages of saving the images into database. The main advantage is easy management of images. You can control the number and size of images stored in your server. You can remove all unnecessary images from the database in a single sql query and you can backup the image data easily. On the other hand, you should be generous of keeping sufficient memory store in your database server.
Inserting Image into Database
To start with, let me explain the SQL Server database table structure we are going to use to insert the image. The table you are going to create to store the image must contain a column of data type IMAGE. This image data type is a Variable-length binary data with a maximum length of 2^31 - 1 (2,147,483,647) bytes. To store the image into this column we are going to convert it into binary string with the help of some IO classes and then insert into the table. For demonstration, we are going to create a table named ImageGallery with four columns in the following structure
Column Name Description Data Type
Img_Id Identity column for Image Id int
Image_Content Store the Image in Binary Format image
Image_Type Store the Image format (i.e. jpeg, gif, png, etc.) varchar
Image_Size Store the Image File Size bigint
After we create table in the database, we can start the coding part.
1. Open your web application in Visual Studio 2005, drag and drop File Upload control and a Button control into the web page.
2. In the code-behind, add the namespace System.IO.
using System.IO;
3. In the Button’s Button1_Click event, write the following code
if (FileUpload1.PostedFile != null
&& FileUpload1.PostedFile.FileName != "")
{
byte[] myimage = new byte[FileUpload1.PostedFile.ContentLength];
HttpPostedFile Image = FileUpload1.PostedFile;
Image.InputStream.Read(myimage, 0, (int)FileUpload1.PostedFile.ContentLength);
SqlConnection myConnection = new SqlConnection(“Your Connection String”);
SqlCommand storeimage = new SqlCommand("INSERT INTO ImageGallery "
+"(Image_Content, Image_Type, Image_Size) "
+" values (@image, @imagetype, @imagesize)", myConnection);
storeimage.Parameters.Add("@image", SqlDbType.Image, myimage.Length).Value = myimage;
storeimage.Parameters.Add("@imagetype", SqlDbType.VarChar, 100).Value
= FileUpload1.PostedFile.ContentType;
storeimage.Parameters.Add("@imagesize", SqlDbType.BigInt, 99999).Value
= FileUpload1.PostedFile.ContentLength;
myConnection.Open();
storeimage.ExecuteNonQuery();
myConnection.Close();
}
To upload the image from any location (your local drive) to the server, we have to use HttpPostedFile object. Point the uploaded file to HttpPostedFile object. Then the InputStream.Read method will read the content of the image by a sequence of bytes from the current stream and advances the position within the stream by the number of bytes it read. So myimage contains the image as binary data. Now we have to pass this data into the SqlCommand object, which will insert it into the database table.
Display the Image in a GridView with Handler
So far, the article explains the way to insert images into the database. The Image is in the database in binary data format. Retrieving this data in an ASP.NET web page is fairly easy, but displaying it is not as simple. The basic problem is that in order to show an image in an apsx page, you need to add an image tag that links to a separate image file through the src attribute or you need to put an Image control in your page and specify the ImageUrl.
For example:
Unfortunately, this approach will not work if you need to show image data dynamically. Although you can set the ImageUrl attribute in code, you have no way to set the image content programmatically. You could first save the data to an image file on the web server’s hard drive, but that approach would be dramatically slower, wastes space, and raises the possibility of concurrency errors if multiple requests are being served at the same time and they are all trying to write the same file.
In these situations, the solution is to use a separate ASP.NET resource that returns the binary data directly from the database. Here HTTP Handler class comes to center stage.
What is Handler?
An ASP.NET HTTP Handler is a simple class that allows you to process a request and return a response to the browser. Simply we can say that a Handler is responsible for fulfilling requests from the browser. It can handle only one request at a time, which in turn gives high performance. A handler class implements the IHttpHandler interface.
For this article demonstration, we are going to display the image in the GridView control along with the data we stored in the table. Here are the steps required to accomplish this:
1. Create a Handler.ashx file to perform image retrieval. This Handler.ashx page will contain only one method called ProcessRequest. This method will return binary data to the incoming request. In this method, we do normal data retrieval process and return only the Image_Content field as bytes of array.
The sample code follows
public void ProcessRequest (HttpContext context)
{
SqlConnection myConnection = new SqlConnection(“YourConnectionString”);
myConnection.Open();
string sql = "Select Image_Content from ImageGallery where Img_Id=@ImageId";
SqlCommand cmd = new SqlCommand(sql, myConnection);
cmd.Parameters.Add("@ImageId", SqlDbType.Int).Value = context.Request.QueryString["id"];
cmd.Prepare();
SqlDataReader dr = cmd.ExecuteReader();
dr.Read();
context.Response.ContentType = dr["Image_Type"].ToString();
context.Response.BinaryWrite((byte[])dr["Image_Content"]);
dr.Close();
myConnection.Close();
}
2. Place a GridView control in your aspx page, with one TemplateField column, add an Image control into the TemplateField's ItemTemplate section. Specify the ImageUrl property as
<asp:TemplateField>
<ItemTemplate>
<asp:Image ID="Image1" runat="server" ImageUrl='<%# "Handler.ashx?id=" + Eval("Img_Id") %>' />
</ItemTemplate>
</asp:TemplateField>
3. Now we can bind the GridView control to display all the records in the table as follows
GridView1.DataSource = FetchAllImagesInfo();
GridView1.DataBind();
Before you bind the GridView, you should write the FetchAllImagesInfo method to return all the records with their image data from the table and then you have to load the images into the GridView control. The code for FetchAllImagesInfo is
public DataTable FetchAllImagesInfo())
{
string sql = "Select * from ImageGallery";
SqlDataAdapter da = new SqlDataAdapter(sql, "Your Connection String");
DataTable dt = new DataTable();
da.Fill(dt);
return dt;
}
That's it. When you run your project, you can see the images got loaded into the GridView control.
This is a very simple explanation to store images into the data source and to retrieve it back to display in the webpage. You can make the logic even simpler and even elaborate it upto your requirements.
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