Solved

Downloading varbinary data into a variable or file

Posted on 2013-06-18
7
289 Views
Last Modified: 2013-10-04
I am looking to download varbinary data into a sqlbinary variable in C# but I am not sure how to get this to work.  I have a class method that is running the transaction from the database and then another small chunk of code that is actully implementing the method.  How am I supposed to get this to work?  I have attached some code below.  Thanks!


 public System.Data.SqlTypes.SqlBinary GetProfilePicture(Guid profileid)
        {
            Profile profile = new Profile();

            SqlBinary profilepic;

            SqlConnection objConnection = new SqlConnection();
            DataSet objDataset = new DataSet();
            SqlDataAdapter objAdapter = new SqlDataAdapter();

            SqlCommand objCommand = new SqlCommand("spGetProfilePictureByProfileId");
            objCommand.CommandType = CommandType.StoredProcedure;

            profile.ProfileId = profileid;


            objConnection.ConnectionString = System.Configuration.ConfigurationManager.ConnectionStrings["DefaultConnection"].ToString();
            objConnection.Open();
            objCommand.Connection = objConnection;
            objCommand.Parameters.Add(new SqlParameter("@ProfileId", profile.ProfileId));

            SqlParameter sqlparam = new SqlParameter();

            sqlparam.ParameterName = "@ProfilePictureUrl";
            sqlparam.Direction = ParameterDirection.Output;
            sqlparam.Size = -1;

            objCommand.Parameters.Add(sqlparam.ParameterName, SqlDbType.VarBinary);
            //objCommand.Parameters.Add(sqlparam);



            //SqlDataReader reader;
            //objCommand.ExecuteNonQuery();

           // reader = objCommand.ExecuteReader();

            System.Text.ASCIIEncoding encoding = new System.Text.ASCIIEncoding();

            using (var reader = objCommand.ExecuteReader())
            {
                while (reader.Read())
                {
                    byte[] raw = (byte[])reader.GetSqlBytes(0).Buffer;
                    profilepic = raw;

                    profile.ProfilePictureUrl = profilepic;
                }

                
            }

          return profile.ProfilePictureUrl;
            
        }      

Open in new window


and below is how I am attempting to retrieve the data from the database:

profileid = Guid.Parse(Session["ProfileId"].ToString());

SqlBinary ProfileImage = profile.GetProfilePicture(profileid);

Open in new window



unfortunately my retrieval process is not working.  How do I do this correctly?  The varbinary data that I am trying to retrieve from the database is an image.  Thanks!
0
Comment
Question by:VBBRett
  • 4
  • 3
7 Comments
 
LVL 1

Accepted Solution

by:
PeterInStingbert earned 500 total points
ID: 39257486
Hi
read a Byte[] within a datareader:

int fieldIndex = 0

if (reader.IsDBNull(fieldIndex ))
    return new byte[0];
else
{
    Byte[] b = new Byte[(reader.GetBytes(fieldIndex , 0, null, 0, int.MaxValue))];
     if (b.Length <= 0)
          return new byte[0];
     else
      {
           this.reader.GetBytes(fieldIndex , 0, b, 0, b.Length);
            return b;
       }
}

Open in new window


Create the Image from Byte[]

Byte[] imageStream = ...

System.Drawing.ImageConverter ic = new System.Drawing.ImageConverter();
image = (System.Drawing.Image)(ic.ConvertFrom(this._imageStream));

Open in new window

0
 
LVL 1

Assisted Solution

by:PeterInStingbert
PeterInStingbert earned 500 total points
ID: 39257575
Sorry typing error in Create Image from...

Byte[] imageStream = ...

System.Drawing.ImageConverter ic = new System.Drawing.ImageConverter();
image = (System.Drawing.Image)(ic.ConvertFrom(imageStream)); 

Open in new window

0
 

Author Comment

by:VBBRett
ID: 39257590
So how would I change my code?
0
Courses: Start Training Online With Pros, Today

Brush up on the basics or master the advanced techniques required to earn essential industry certifications, with Courses. Enroll in a course and start learning today. Training topics range from Android App Dev to the Xen Virtualization Platform.

 
LVL 1

Assisted Solution

by:PeterInStingbert
PeterInStingbert earned 500 total points
ID: 39257660
Hi,
It is a Problem to test w/o Information about Profil
but try this:

public System.Data.SqlTypes.SqlBinary GetProfilePicture(Guid profileid)
        {
            Profile profile = new Profile();

            SqlBinary profilepic;

            SqlConnection objConnection = new SqlConnection();
            DataSet objDataset = new DataSet();
            SqlDataAdapter objAdapter = new SqlDataAdapter();

            SqlCommand objCommand = new SqlCommand("spGetProfilePictureByProfileId");
            objCommand.CommandType = CommandType.StoredProcedure;

            profile.ProfileId = profileid;


            objConnection.ConnectionString = System.Configuration.ConfigurationManager.ConnectionStrings["DefaultConnection"].ToString();
            objConnection.Open();
            objCommand.Connection = objConnection;
            objCommand.Parameters.Add(new SqlParameter("@ProfileId", profile.ProfileId));

            SqlParameter sqlparam = new SqlParameter();

            sqlparam.ParameterName = "@ProfilePictureUrl";
            sqlparam.Direction = ParameterDirection.Output;
            sqlparam.Size = -1;

            objCommand.Parameters.Add(sqlparam.ParameterName, SqlDbType.VarBinary);
            //objCommand.Parameters.Add(sqlparam);



            //SqlDataReader reader;
            //objCommand.ExecuteNonQuery();

           // reader = objCommand.ExecuteReader();

            System.Text.ASCIIEncoding encoding = new System.Text.ASCIIEncoding();

            using (var reader = objCommand.ExecuteReader())
            {
               
                while (reader.Read())
                {

                    int fieldIndex = 0;
                    Byte[] raw;

                    if (reader.IsDBNull(fieldIndex))
                        raw = new byte[0];
                    else
                    {
                        raw = new Byte[(reader.GetBytes(fieldIndex, 0, null, 0, int.MaxValue))];
                        if (raw.Length > 0)
                            reader.GetBytes(fieldIndex, 0, raw, 0, raw.Length);
                    }

                    profilepic = raw;
                    profile.ProfilePictureUrl = profilepic;
                }                
            }

          return profile.ProfilePictureUrl;
            
        }       

Open in new window

0
 

Author Comment

by:VBBRett
ID: 39257839
There seems to be a problem with the code not reading the reader.  It appears to drop out of the loop when it gets to that point.  I don't understand, it completely skipped the using (var reader) or the while (reader) loop.  Why would it do that?
0
 
LVL 1

Expert Comment

by:PeterInStingbert
ID: 39265015
Your original code is:

 using (var reader = objCommand.ExecuteReader())
            {
                while (reader.Read())
                {
                    byte[] raw = (byte[])reader.GetSqlBytes(0).Buffer;
                    profilepic = raw;

                    profile.ProfilePictureUrl = profilepic;
                }
            }

          return profile.ProfilePictureUrl;

Open in new window


Reader.Read()  works strictly Forward
--> The default position of a data reader is before the first record. Therefore, you must call Read to begin accessing data.

If there is no result (no records) in your "select Statement"

  while (reader.Read())
{
}

never Loop.
0
 

Author Comment

by:VBBRett
ID: 39302835
So is it better to throw into a file in a file directory or stream it to a file in a website?
0

Featured Post

Gigs: Get Your Project Delivered by an Expert

Select from freelancers specializing in everything from database administration to programming, who have proven themselves as experts in their field. Hire the best, collaborate easily, pay securely and get projects done right.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

User art_snob (http://www.experts-exchange.com/M_6114203.html) encountered strange behavior of Android Web browser on his Mobile Web site. It took a while to find the true cause. It happens so, that the Android Web browser (at least up to OS ver. 2.…
It was really hard time for me to get the understanding of Delegates in C#. I went through many websites and articles but I found them very clumsy. After going through those sites, I noted down the points in a easy way so here I am sharing that unde…
Two types of users will appreciate AOMEI Backupper Pro: 1 - Those with PCIe drives (and haven't found cloning software that works on them). 2 - Those who want a fast clone of their boot drive (no re-boots needed) and it can clone your drive wh…
A short tutorial showing how to set up an email signature in Outlook on the Web (previously known as OWA). For free email signatures designs, visit https://www.mail-signatures.com/articles/signature-templates/?sts=6651 If you want to manage em…

776 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question