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Uploading Images to a Database

By Dave Wanta, published on 01 Aug 2003
Page 3 of 5
  1. Introduction
  2. Building our Webform
  3. Working with the Uploaded Image
  4. The Good Stuff
  5. Full Source Code

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)
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.

Comments

  1. anu radha
    20 Mar 2009 at 14:52
    Hi can i upload images using open dialog in asp.net by selecting multiple images at a time by single button click as like we have open file dialog in windows appllication
  2. Jon Kress
    15 Jun 2006 at 13:52

    This may sound weird but I think I'm the only one not having perfect success with this.

    I'm getting a System.NullReferenceException: Object reference not set to an instance of an object.
    on the line 


    Stream imgStream = UploadFile.PostedFile.InputStream;

    [NullReferenceException: Object reference not set to an instance of an object.]
       DBImages.UploadImage.BtnUpload_Click(Object sender, EventArgs e) in c:\Inetpub\wwwroot\official-certify\Media\SubmitJon.aspx.cs:70
       System.Web.UI.WebControls.Button.OnClick(EventArgs e) +105
       System.Web.UI.WebControls.Button.RaisePostBackEvent(String eventArgument) +107
       System.Web.UI.WebControls.Button.System.Web.UI.IPostBackEventHandler.RaisePostBackEvent(String eventArgument) +7
       System.Web.UI.Page.RaisePostBackEvent(IPostBackEventHandler sourceControl, String eventArgument) +11
       System.Web.UI.Page.RaisePostBackEvent(NameValueCollection postData) +33

      System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +5102










    I'm not sure why I'm getting this error. I copied the code verbatum and then added references for my other fields that I'm pulling in.

    I have no idea what the stack trace is all about, like I understand stacks, but the way these are formatted makes no sense to me, although here's what's in it maybe you guys will know.

    ((my button is exactly the same just named BtnUpload as opposed to UploadBtn.))



    If anyone could help it would be greatly appreciated. It's been driving me nuts I've run into a bunch of other errors that I've fixed, mostly missing a ";" but I've taken care of them all, this is the only one I haven't figured out yet (well unless there's more after this one is fixed)

    Thanks in advance for the help








  3. 02 Nov 2005 at 09:48

    The easiest way to upload and resize an image to the internet and automatically create thumbnails is I-Load.
    I-Load is a FREE ASP.NET web control with numerous benefits and features.
    You can download I-Load (it's FREE!) and view an online demo here:


    http://www.radactive.com/en/Products/ILoad/Overview.aspx

  4. harshguglani
    03 Sep 2005 at 08:39
    Hi,   Whts the benifit of uploading images in database server when i can place images on web server in my directory and accesss them. Reply soon.
  5. Leslie Bell
    02 Aug 2005 at 11:06
    The explanatory text says "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" but I don't see enctype in the code samples. Have I missed something?

    Les
  6. Scott Hamm
    08 Jul 2005 at 16:13

    Better control of file updates.  On file server, anybody can update files without letting anyone know about it.  If you store a file inside SQL database, it will show who last updated files, inform users when it expires, requiring updates and so on.  I administer 230 manual documents that shows original creator, date of implementation, maintainer and updated date.  Very useful and uniform in updates and maintenance.


  7. oramike
    18 May 2005 at 14:57

    i have been able to implement this and i now upload all sorts of documents including images into my sql server database. i now need to retrieve the document in the original format (.doc, .xls, .jpg, etc). pls, i do i achieve that?

  8. sandy007
    28 Dec 2004 at 05:32

    Hello,


    I need some more idea on this topic. What is benifit to store data into SQL server (means into BLOB chartype in SQL). Why can not we just store file on to PC and just add link name into SQL.


    Please can anybody give me this ans.


    Thanks

  9. talon121
    20 Sep 2003 at 22:19

    Ok,


    Im sorta new to ASP.Net and Ive got the image upload to blob working ...


    But for this to be moreso practical, it would be nice to see the ability to upload into another field, the thumbnail automatically generated from the blob data. (or when it gets uploaded).


    Can someone help or point me in the right direction?!?!


    Im desperate

  10. Developer Fusion Bot
    01 Jan 1999 at 00:00

    This thread is for discussions of Uploading Images to a Database.

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