Uploading Images to a Database ( C# ) - Part I

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September 05, 2001

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Uploading images to a Sql Server database is extremely easy using ASP.NET and C#. A couple of months ago I wrote a similar article, using VB.NET. This article will show you how to upload Images (or any Binary Data ) to a Sql Server database using ASP.NET and C#. Part II, Retrieving Images from a Database ( C# ) , will show you how extract images from a database.

Building the Database Table

We start out by building our database table. Our image table is going to have a few columns describing the image data, plus the image itself. Here is the sql required to build our table in SQL Server or MSDE.

CREATE TABLE [dbo].[image] (
[img_pk] [int] IDENTITY (1, 1) NOT NULL ,
[img_name] [varchar] (50) NULL ,
[img_data] [image] NULL ,
[img_contenttype] [varchar] (50) NULL
) ON [PRIMARY] TEXTIMAGE_ON [PRIMARY]
GO

ALTER TABLE [dbo].[image] WITH NOCHECK ADD
CONSTRAINT [PK_image] PRIMARY KEY NONCLUSTERED
(
[img_pk]
) ON [PRIMARY] GO

I'm a great fan of having a single column primary key, and making that key an Identity column, in our example, that column is img_pk. The next column is img_name, which is used to store a friendly name of our image, for example "Mom and Apple Pie". img_data is actually our image data column, and is where we will be storing our binary image data. img_contenttype will be used to record the content-type of the image, for example "image/gif" or "image/jpeg" so we will know what content-type we need to output back to the client, in our case the browser.

Building our Webform

Now that we have a warm, fuzzy place to store our images, lets build a webform to upload our images into the database.

Enter A Friendly Name<input type=text id=txtImgName runat="server" >
<asp:RequiredFieldValidator id=RequiredFieldValidator1 runat="server" ErrorMessage="Required" ControlToValidate="txtImgName"></asp:RequiredFieldValidator>

<br>Select File To Upload:
<input id="UploadFile" type=file runat=server>
<asp:button id=UploadBtn Text="Upload Me!" OnClick="UploadBtn_Click" runat="server"></asp:button>
</form>

The first interesting point about our webform, is the attribute "enctype". Enctype tells the browser and server that we will be uploading some type of binary data. This binary data needs to be parsed, using a different mechanism from our normal text data. The next control we of interest is the type=file control. This control will present the user with an upload file dialog box. The user browses for the file they want to upload.

Working with the Uploaded Image

Once the user posts the data, we have to be able to parse the binary data and send it to the database. Along with the main body of the code, we use a helper function called SaveToDB() to achieve this.

private int SaveToDB(string imgName, byte[] imgbin, string imgcontenttype)
{
//use the web.config to store the connection string
SqlConnection connection = new SqlConnection(ConfigurationSettings.AppSettings["DSN"]);
SqlCommand command = new SqlCommand( "INSERT INTO Image (img_name,img_data,img_contenttype) VALUES ( @img_name, @img_data,@img_contenttype )", connection );

SqlParameter param0 = new SqlParameter( "@img_name", SqlDbType.VarChar,50 );
param0.Value = imgName;
command.Parameters.Add( param0 );

SqlParameter param1 = new SqlParameter( "@img_data", SqlDbType.Image );
param1.Value = imgbin;
command.Parameters.Add( param1 );

SqlParameter param2 = new SqlParameter( "@img_contenttype", SqlDbType.VarChar,50 );
param2.Value = imgcontenttype;
command.Parameters.Add( param2 );

connection.Open();
int numRowsAffected = command.ExecuteNonQuery();
connection.Close();

return numRowsAffected;
}

In this function we are passing in 3 different parameters
imgName - the friendly name we want to give out image data
imgbin -- the binary or Byte array of our data
imgcontenttype - the content type of our image. For example: image/gif or image/jpeg

There are 3 parameters as SQLParameters and defines the type. Our first SQLParameter is @img_name and is defined as a VarChar with a length of 50. The 2nd parameter, @img_data, is the binary or Byte() of data and is defined with a data type of Image. The last parameter is @img_contenttype, is defined as a VarChar with a length of 50 characters. The remainder of the function opens a connection to the database and executes the command by calling command.ExecuteNonQuery().

Calling our Functions

Ok, now that we have our worker functions written, let's go ahead and get our image data.

Stream imgStream = UploadFile.PostedFile.InputStream;
int imgLen = UploadFile.PostedFile.ContentLength;
string imgContentType = UploadFile.PostedFile.ContentType;
string imgName = txtImgName.Value;
byte[] imgBinaryData = new byte[imgLen];

We need to access three important pieces of data for our example. We need the image:
Name (imgName_value)
Content-Type (imgContentType)
and the Image Data. (imgBindaryData)
First we access to the image stream, which we are able to get by using the property UploadFile.PostedFile.InputStream. (Remember, UploadFile was the name of our upload control on the webform). We also need to know how long the Byte array we are going to create needs to be. We can get this number by calling UploadFile.PostedFile.ContentLength, and storing it's value in imgLen. Once we have the length of the image, we create a byte array by byte[] imgBinaryData = new byte[imgLen]; We access the content type of the image by accessing the ContentType property of UploadFile.PostedFile. Lastly we need the friendly name we are going to use for the image.

The Good Stuff

Ok, we know how to connect to the database, we know how to insert data into the database, and we have access to the uploaded image's properties. But how do we pass the stream of the image to SaveToDB(). Again, .NET comes to the rescue. With 1 line of code we are able to access the image stream and convert it to a Byte array.

int n = imgStream.Read(imgBinaryData,0,imgLen);

The stream object provides a method called Read(). Read() takes 3 parameters:
buffer - An array of bytes. A maximum of count bytes are read from the current stream and stored in buffer.
offset -The byte offset in buffer at which to begin storing the data read from the current stream.
count - The maximum number of bytes to be read from the current stream.
So we pass in our Byte array, imgBinaryData; the place to start at, 0; and the amount of bytes we want to read. n number of bytes read into our array is returned.

Extending Beyond Images

Because we are able to access the binary stream of data, images are not the only object we can store in the database. Some other objects might be streaming video, com objects, or sound clips. As an example I also uploaded a streaming avi into my database. I ran a select query to show the results.

Conclusion

So there we have it, ASP.NET provides us some easy functionality for uploading images into a database. In Part II, we will actually look at pulling these images out of a database and sending them to a browser. The complete code used for this article can be found below.

Cheers!
Dave
www.123aspx.com

Image SQL

UploadImage.aspx

<%@ Page language="c#" Src="UploadImage.aspx.cs" Inherits="DBImages.UploadImage" %>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN" >
<HTML>
<HEAD>
</HEAD>
<body bgcolor=#ffffff>

<form enctype="multipart/form-data" runat=server id=form1 name=form1>
<h3>The ASPFree Friendly Image Uploader</h3>
Enter A Friendly Name<input type=text id=txtImgName runat="server" >
<asp:RequiredFieldValidator id=RequiredFieldValidator1 runat="server" ErrorMessage="Required" ControlToValidate="txtImgName"></asp:RequiredFieldValidator>

<br>Select File To Upload:
<input id="UploadFile" type=file runat=server>
<asp:button id=UploadBtn Text="Upload Me!" OnClick="UploadBtn_Click" runat="server"></asp:button>
</form>

</body>
</HTML>

UploadImage.aspx.cs ( codebehind file)

using System;
using System.Configuration;
using System.Collections;
using System.ComponentModel;
using System.Data;
using System.Data.SqlClient;
using System.Drawing;
using System.Web;
using System.IO;
using System.Web.SessionState;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.HtmlControls;

namespace DBImages
{
public class UploadImage : System.Web.UI.Page
{
protected System.Web.UI.WebControls.Button UploadBtn;
protected System.Web.UI.WebControls.RequiredFieldValidator RequiredFieldValidator1;
protected System.Web.UI.HtmlControls.HtmlInputText txtImgName;
protected System.Web.UI.HtmlControls.HtmlInputFile UploadFile;

public UploadImage() { }

private void Page_Load(object sender, System.EventArgs e){ }

public void UploadBtn_Click(object sender, System.EventArgs e)
{
if (Page.IsValid) //save the image
{
Stream imgStream = UploadFile.PostedFile.InputStream;
int imgLen = UploadFile.PostedFile.ContentLength;
string imgContentType = UploadFile.PostedFile.ContentType;
string imgName = txtImgName.Value;
byte[] imgBinaryData = new byte[imgLen];
int n = imgStream.Read(imgBinaryData,0,imgLen);

int RowsAffected = SaveToDB( imgName, imgBinaryData,imgContentType);
if ( RowsAffected>0 )
{
Response.Write("<BR>The Image was saved");
}
else
{
Response.Write("<BR>An error occurred uploading the image");
}

}
}

private int SaveToDB(string imgName, byte[] imgbin, string imgcontenttype)
{
//use the web.config to store the connection string
SqlConnection connection = new SqlConnection(ConfigurationSettings.AppSettings["DSN"]);
SqlCommand command = new SqlCommand( "INSERT INTO Image (img_name,img_data,img_contenttype) VALUES ( @img_name, @img_data,@img_contenttype )", connection );

SqlParameter param0 = new SqlParameter( "@img_name", SqlDbType.VarChar,50 );
param0.Value = imgName;
command.Parameters.Add( param0 );

SqlParameter param1 = new SqlParameter( "@img_data", SqlDbType.Image );
param1.Value = imgbin;
command.Parameters.Add( param1 );

SqlParameter param2 = new SqlParameter( "@img_contenttype", SqlDbType.VarChar,50 );
param2.Value = imgcontenttype;
command.Parameters.Add( param2 );

connection.Open();
int numRowsAffected = command.ExecuteNonQuery();
connection.Close();

return numRowsAffected;
}
}
}

Web.Config