In a previous entry, I have shown how to store images to a database table. Now I will show you how to retrieve it and show it on an ASP.NET
Image
control. There is no straightforward method for showing it like “ImageControl.Image = ImageStream….
” However it can be achieved using a Generic Handler.
Add a ‘Generic Handler’ to your ASP.NET web application. And in this example I will name it
‘getImageFromDB.ashx’. By default, IHttpHandler
will be implemented (ProcessRequest
and
IsReusable
methods will be implemented). And I will add another method called ‘GetImage
’ and alter the ‘ProcessRequest
’ method. And the finished
handler should be similar to this:
1: using System;
2: using System.Drawing;
3: using System.Drawing.Imaging;
4: using System.IO;
5: using System.Web;
6: using System.Data;
7: using System.Data.SqlClient;
8:
9: namespace MyWebApplication
10: {
11:
12: public class getImageFromDB : IHttpHandler
13: {
14: public void ProcessRequest(HttpContext context)
15: {
16: context.Response.Clear();
17:
18: if (!String.IsNullOrEmpty(context.Request.QueryString["empID"]))
19: {
20: int id = Int32.Parse(context.Request.QueryString["empID"]);
21:
22: Image image = GetImage(id);
23:
24: context.Response.ContentType = "image/jpeg";
25: image.Save(context.Response.OutputStream, ImageFormat.Jpeg);
26: }
27: else
28: {
29: context.Response.ContentType = "text/html";
30: context.Response.Write("<p>Need a valid id</p>");
31: }
32: }
33:
34: public bool IsReusable
35: {
36: get
37: {
38: return false;
39: }
40: }
41:
42: private Image GetImage(int empID)
43: {
44:
45: MemoryStream memoryStream = new MemoryStream();
46:
47:
48: string connectionString = "Password=PWD;Persist Security " +
"Info=True;User ID=USER;Initial Catalog=SampleDatabase;Data Source=SQLSERVER";
49: using (SqlConnection sqlConnection = new SqlConnection(connectionString))
50: {
51: using (SqlCommand sqlCommand = new SqlCommand("SELECT emp_id, " +
"emp_name, emp_image FROM Employee where emp_id = " +
empID.ToString(), sqlConnection))
52: {
53: sqlConnection.Open();
54: SqlDataReader sqlDataReader = sqlCommand.ExecuteReader();
55:
56: if (sqlDataReader.HasRows)
57: {
58: sqlDataReader.Read();
59: byte[] btImage = (byte[])sqlDataReader["emp_image"];
60:
61: memoryStream = new MemoryStream(btImage, false);
62: }
63: }
64: sqlConnection.Close();
65: }
66: return Image.FromStream(memoryStream);
67: }
68: }
69: }
And you can call the handler and display the image using the following syntax:
1: private void GetImageFromDatabase(int empID)
2: {
3: imageControl.ImageUrl = "getImageFromDB.ashx?empID=" + empID.ToString();
4: }
My passion lies in building business intelligence and data-based solutions, writing about things I work with and talking about it. New technologies relevant to my line of work interest me and I am often seen playing with early releases of such technologies.
My current role involves architecting and building a variety of data solutions, providing database maintenance and administration support, building the organization’s data practice, and training and mentoring peers.
My aspiration over the next several years is to achieve higher competency and recognition in the field of Data Analytics and move into a career of data science.
Specialities: SQL Server, T-SQL Development, SQL Server Administration, SSRS, SSIS, C#, ASP.Net, Crystal Reports