how to check if the data being entered exists already - vb.net

Question

here is my code to submit data to my csv file. How do I check to see if the data already exists before saving it.
Dim csvFile As String = My.Application.Info.DirectoryPath & "\HoseData.csv"
Dim outFile As IO.StreamWriter = My.Computer.FileSystem.OpenTextFileWriter(csvFile, True)
'If My.Computer.FileSystem.FileExists(csvFile) Then
'outFile.WriteLine("job number, sales order number, date, requested by, serial number, hose type, hose size, fitting 1, fitting 2, qty, oal, cut off, offset, crimp 1, crimp 2, cleaned, pigged", False)
'End If
outFile.WriteLine(TextBox1.Text & "," & TextBox2.Text & "," & """" & DateTimePicker1.Text & """" & "," & ComboBox1.Text & "," & TextBox3.Text & "," & ListBox2.Text & "," & ListBox3.Text & "," & TextBox11.Text & "," & TextBox12.Text & "," & NumericUpDown1.TextAlign & "," & TextBox4.Text & "," & TextBox5.Text & "," & TextBox6.Text & "," & TextBox9.Text & "," & TextBox10.Text & "," & ListBox4.Text & "," & ListBox5.Text)
MessageBox.Show("INPUT WAS SAVED")
Dim butt As System.Windows.Forms.Button = DirectCast(sender, System.Windows.Forms.Button)
butt.Enabled = False
'butt.Visible = False
outFile.Close()
Console.WriteLine(My.Computer.FileSystem.ReadAllText(csvFile))

Answer 1

Is this what you're looking for?
Dim fn As String = My.Application.Info.DirectoryPath & "\HoseData.csv"
Dim fileText As String
Dim outString As String = TextBox1.Text & "," & TextBox2.Text & "," & """" & DateTimePicker1.Text & """" & "," & ComboBox1.Text & "," & TextBox3.Text & "," & ListBox2.Text & "," & ListBox3.Text & "," & TextBox11.Text & "," & TextBox12.Text & "," & NumericUpDown1.TextAlign & "," & TextBox4.Text & "," & TextBox5.Text & "," & TextBox6.Text & "," & TextBox9.Text & "," & TextBox10.Text & "," & ListBox4.Text & "," & ListBox5.Text
Using reader As StreamReader = File.OpenText(fn)
fileText = reader.ReadToEnd
End Using
Using outFile As IO.StreamWriter = My.Computer.FileSystem.OpenTextFileWriter(fn, True)
If fileText.Contains(outString) Then
'do stuff when the string is already present, e.g.:
MessageBox.Show("You've already entered that one.")
Else
'do stuff when it isn't, e.g.:
outFile.WriteLine(outString)
End If
End Using