Load CSV to Listview including Subitems
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  1. #1
    Join Date
    Apr 2014
    Posts
    2

    Load CSV to Listview including Subitems

    Hello all!

    Using Visual Basic 2008, I Want to load a csv file to Listview.

    I am new to LINQ, and had some great performance increase in using LINQ (compared to loops) when loading a csv file to a single column Listview.

    Example Code:

    Code:
    Dim items() As ListViewItem = (From line In IO.File.ReadAllLines(thefiletoread) Where line.Length <> 0 Select New ListViewItem(RTrim(line.ToUpper))).ToArray
    ListView2.Items.AddRange(items)
    altought, i have not found any way to do the exact same thing, but in a multiple column Listview.

    I do not wish to use loops, since LINQ syntax works so well.

    any of you guys have an idea?

  2. #2
    Join Date
    Feb 2000
    Location
    OH - USA
    Posts
    1,891

    Re: Load CSV to Listview including Subitems

    I see you mention performance, but I don't really see how LINQ could be quicker in this case. A loop will almost always give significantly better performance when compared to a LINQ method.

    If you can provide a file layout and the target listview column setup, I'm sure someone can give you a quick example of how to do this.
    Good Luck,
    Craig - CRG IT Solutions - Microsoft Gold Partner

    -My posts after 11/2011 = .NET 4.x and Visual Studio 2012
    -My posts after 02/2010 = .NET 4.0 and Visual Studio 2010
    -My posts after 12/2007 = .NET 3.5 and Visual Studio 2008
    -My posts after 04/2007 = .NET 3.0 and Visual Studio 2005
    -My posts before 04/2007 = .NET 1.1/2.0

    *I do not follow threads, so if you have a secondary question, message me.

  3. #3
    Join Date
    Apr 2014
    Posts
    2

    Re: Load CSV to Listview including Subitems

    Hello!

    Thanks for your answer....

    The input text file is a TAB separated file. I have no idea upon import how much columns is needed in the Listview.

    By Default my List view has a single column. If i detect the presence of one or more TAB character, i programmatically add the column to add the data split from the original input String.

    So let's say my input file is: (note replaced TABs by Spaces since the website inputbox does not allow for TABs)

    Banana Fruit Yellow
    Apple Fuit Red
    Cocumber Vegetable Green

    Note1: I do not know the quantity of TAB separator Characters (if any), but all lines contain the same number of column. (from 0 to 83 approx)
    Note2: My file can contain up to 100 000 lines

    Currently, my code is:

    Code:
    Dim items() As ListViewItem = (From line In IO.File.ReadAllLines(thefiletoread) Where line.Length <> 0 Select New ListViewItem(RTrim(line.ToUpper))).ToArray
    ListView2.Items.AddRange(items)
    This is quick, but has no column Logic...

    So i would need to

    -Import the file Line by line
    -Scan the first line as string and determine quantity of TAB separator Characters
    -Add the Missing columns to Listview
    -Split the Input Line String
    -Loop trough all Portions of the Splitted string to add to listview Item variable (not adding to Listview for now)
    -Continue looping trough all line of input document
    -Detect End if File
    -Add listview Item Variable to Listview with addrange

    Do you agree?

    I really have the feeling that importing using Linq is quicker than loops... but i may be wrong.
    I will have to test this new logic and compare the time it takes.
    My past experience of importing big text files could take up to 5 minutes (with no multi-column analysis), when similar Ling import would take less than 30 sec.

    Here is base code from other web site: (http://bytes.com/topic/visual-basic-...view-add-items)
    Code:
    Dim i As ListViewItem = ListView1.Items.Add("First portion from file")
    i.SubItems.Add("Second portion from file")
    i.SubItems.Add("third portion from file")

  4. #4
    Join Date
    Feb 2000
    Location
    OH - USA
    Posts
    1,891

    Re: Load CSV to Listview including Subitems

    Here is a quick example that should give some insight:

    Code:
        Private Sub LoadDataToListview()
    
            Dim filePath As String = "C:\myfile.txt"
            Dim streamReader As New IO.StreamReader(filePath)
            Dim streamText As String
            Dim listViewItem As ListViewItem
    
            While Not streamReader.EndOfStream
    
                streamText = streamReader.ReadLine()
    
                If Not String.IsNullOrEmpty(streamText) Then
    
    
                    If Not ListView1.Columns.Count = 0 Then
                        '
                        'Add listview items
                        '
                        listViewItem = New ListViewItem(streamText.Split(ControlChars.Tab))
                        '
                        'Do additional work on values here
                        '
                        ListView1.Items.Add(listViewItem)
                    Else
                        '
                        'Populate Column Headers
                        '
                        For Each value As String In streamText.Split(ControlChars.Tab)
                            ListView1.Columns.Add(value)
                        Next
                    End If
    
                End If
    
            End While
    
            streamReader.Dispose()
    
    
        End Sub
    Good Luck,
    Craig - CRG IT Solutions - Microsoft Gold Partner

    -My posts after 11/2011 = .NET 4.x and Visual Studio 2012
    -My posts after 02/2010 = .NET 4.0 and Visual Studio 2010
    -My posts after 12/2007 = .NET 3.5 and Visual Studio 2008
    -My posts after 04/2007 = .NET 3.0 and Visual Studio 2005
    -My posts before 04/2007 = .NET 1.1/2.0

    *I do not follow threads, so if you have a secondary question, message me.

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