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c# asp streamwriter append csv output

Posted on 2009-04-02
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Last Modified: 2012-05-06
Hi,

I have a form that is a questionnaire.  I am trying to collect the answers into a csv form.  One line per submit.

I am using the streamwriter.  The only way I could figure out how to do this was to open the file, copy the contents, write them to the new file then add to it. I could not figure out how to append to the file any other way.  

Every time the form is submitted, a blank line is added.

Here are the results of submitting the form 5 times, there is a blank line between each line of actual data:


/wEPDwUKLTQ2MDIzNTYwMmRkPlZhgR1uqeRKobS+TutZOKNgPeM=,one,two,Submit

/wEPDwUKLTQ2MDIzNTYwMmRkPlZhgR1uqeRKobS+TutZOKNgPeM=,three,four,Submit

/wEPDwUKLTQ2MDIzNTYwMmRkPlZhgR1uqeRKobS+TutZOKNgPeM=,five,six,Submit

/wEPDwUKLTQ2MDIzNTYwMmRkPlZhgR1uqeRKobS+TutZOKNgPeM=,seven,eight,Submit

/wEPDwUKLTQ2MDIzNTYwMmRkPlZhgR1uqeRKobS+TutZOKNgPeM=,nine,ten,Submit



Can I somehow just append the file instead of having to copy the contents first?

Can I somehow delete the blank lines?

Thanks,
Bonnie
protected void Button1_Click(object sender, EventArgs e)
    {
 
        String outputFile = Server.MapPath("./results.csv");
        StreamReader sr = new StreamReader(inputFile);
        String filecontents = sr.ReadToEnd();
        sr.Close();
 
        StreamWriter gw = new StreamWriter(outputFile, false);
        string answers = "";
 
        gw.WriteLine(filecontents);
 
        foreach (string item in Request.Form)
        {
           
            if (Request.Form[item] != null)
            {
                if (answers.Length == 0)
                {
                    answers = Request.Form[item];
                }
                else 
                {
                    answers = answers + "," + Request.Form[item];
                }
                
            }
        }
        gw.WriteLine(answers);
        gw.Close();
    }
}

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Question by:Bonnie_K
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6 Comments
 
LVL 18

Assisted Solution

by:ChetOS82
ChetOS82 earned 600 total points
ID: 24048848
I would forget the StreamWriter and just use the System.IO.File.AppendText method.  You pass a file name and the string you want to append to the file.
0
 
LVL 21

Accepted Solution

by:
Craig Wagner earned 1400 total points
ID: 24054437
StreamWriter has an overload the takes a path and a boolean indicating whether you want to overwrite or not.

using( StreamWriter writer = new StreamWriter( myFilePath, true ) )
{
    writer.WriteLine( someStuffToWrite );
}

My guess is that blank lines are an artifact of your copying operation. You're probably using a WriteLine where you should be using a Write somewhere. I think it's a red herring that you shouldn't spend any time on until you resolve the first issue.
0
 
LVL 21

Expert Comment

by:Craig Wagner
ID: 24054498
P.S. Here's a link to the MSDN info for that constructor...

http://msdn.microsoft.com/en-us/library/36b035cb.aspx

AppendText only opens the file for Append and returns a StreamWriter. AppendAllText would open the file, append the text and close the file.

So you've got three choices on how to proceed, depending on what your specific needs are.
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Author Comment

by:Bonnie_K
ID: 24054660
I changed gw.WriteLine(filecontents); to gw.Write(filecontents); and the extra lines are gone.  Thanks a lot.
0
 

Author Closing Comment

by:Bonnie_K
ID: 31565733
I am splitting the points because I did not get a chance to test the append method, am guessing it would work and I appreciate the contribution.  Hope that's OK.
0
 

Author Comment

by:Bonnie_K
ID: 24054801
Changing the streamwriter to:   StreamWriter gw = new StreamWriter(outputFile,true); and getting rid of the streamreader \ copy  also performed an append function
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