Divergence Hosting Technical Blog

While there are many tutorials for ASP.NET on uploading and saving a file to the disk as well as read and parsing a file from the disk, there is no simple tutorial for uploading, reading and parsing the data in memory. A client of ours needed to do this so I thought I’d list out the basics.

First you need a fileupload control and button on the ASPX page
<asp:FileUpload ID="file1" runat="server" />
<asp:Button ID="btnUpload" runat="server" OnClick="btnUpload_Click" />

Then code you button handler

(You’ll need to use/import the following libraries System.IO, System.Text)

C#
// process file
Stream theStream = file1.PostedFile.InputStream;

VB.NET
' process file
Dim theStream As Stream = file1.PostedFile.InputStream

The code above simply creates a stream and sets it to the file you just uploaded.
Next we instantiate a stream reader and pass in the stream we just created

C#
using (StreamReader sr = new StreamReader(theStream))
{
....
}

VB.NET
Using sr As New StreamReader(theStream)
....
End Using

The … is just a placeholder for the code we’ll put in next. You can see that we’re just going to use the stream reader to do some stuff. We want to read each line in the file and place that line into a variable we can manipulate

C#
string line;
while ((line = sr.ReadLine()) != null)
{
....
}

VB.NET
Dim line As String = sr.ReadLine()
While Not line Is Nothing

line = sr.ReadLine() ' CRITICAL line else you will go in an endless loop
End While

Now, assuming our upload file is in the following format

ID|Name

Then we want to split the line and we’ll have our ID and Name for each line!

C#
// split the line
string[] tmpArray = line.Split(Convert.ToChar("|"));

Response.Write("ID" + tmpArray[0].ToString() + " Name:" + tmpArray[1].ToString() + "<BR>");

VB.NET
' split the line
Dim tmpArray() As String = line.Split(Convert.ToChar("|"))
Response.Write("ID" & tmpArray(0).ToString() & " Name:" & tmpArray(1).ToString() &
"<BR>")

There you have it. Now that you have your data, you can do whatever you like with it, throw it in the DB or dump it to a file.

The complete code looks like this
C#
// process file
Stream theStream = file1.PostedFile.InputStream;

using (StreamReader sr = new StreamReader(theStream))
{
string line;
while ((line = sr.ReadLine()) != null)
{
// split the line
string[] tmpArray = line.Split(Convert.ToChar("|"));

Response.Write("ID" + tmpArray[0].ToString() + " Name:" + tmpArray[1].ToString() + "<BR>");
}
}

VB.NET
Protected Sub btnUpload_Click(ByVal sender As Object, ByVal e As EventArgs)
' process file
Dim theStream As Stream = file1.PostedFile.InputStream

Using sr As New StreamReader(theStream)
Dim line As String = sr.ReadLine()
While Not line Is Nothing
'split the line
Dim tmpArray() As String = line.Split(Convert.ToChar("|"))
Response.Write("ID" & tmpArray(0).ToString() & " Name:" & tmpArray(1).ToString() & "<BR>")
line = sr.ReadLine()
End While
End Using
End Sub