Question

What I am trying to do may be better for use with SQL Server but I have seen many applications in the past that simply work on text files and I am wanting to try to imitate the same behaviour that those applications follow.

I have a list of URL’s in a text file. This is simple enough to open and read line by line, but how can I store additional data from the file and query the data?

E.g.
Text File:

http://link1.com/ - 0
http://link2.com/ - 0
http://link3.com/ - 1
http://link4.com/ - 0
http://link5.com/ - 1

Then I will read the data with:

Private Sub ButtonX2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles ButtonX2.Click
        OpenFileDialog1.Filter = "*txt Text Files|*.txt"
        If OpenFileDialog1.ShowDialog() = DialogResult.OK Then
            Dim AllText As String = My.Computer.FileSystem.ReadAllText(OpenFileDialog1.FileName)
            Dim Lines() = Split(AllText, vbCrLf)
            Dim list = New List(Of Test)
            Dim URLsLoaded As Integer = 0
            For i = 0 To UBound(Lines)
                If Lines(i) = "" Then Continue For
                Dim URLInfo As String() = Split(Lines(i), " - ")
                If URLInfo.Count < 6 Then Continue For
                list.Add(New Test(URLInfo(0), URLInfo(1)))
                URLsLoaded += 1
            Next
            DataGridViewX1.DataSource = list
            LabelX5.Text = URLsLoaded.ToString()
        End If
    End Sub

So as you can see, above I am prompting the user to open a text file, afterwards it is displayed back to the user in a datagridview.

Now here is my issue, I want to be able to query the data, E.g. Select * From URLs WHERE active=’1′ (Too used to PHP + MySQL!)

Where the 1 is the corresponding 1 or 0 after the URL in the text file.

In the above example the data is being stored in a simple class as per below:

Public Class Test
    Public Sub New(ByVal URL As String, ByVal Active As Integer)
        _URL = URL
        _Active = Active
    End Sub

    Private _URL As String
    Public Property URL() As String
        Get
            Return _URL
        End Get
        Set(ByVal value As String)
            _URL = value
        End Set
    End Property

    Private _Active As String
    Public Property Active As String
        Get
            Return _Active
        End Get
        Set(ByVal value As String)
            _Active = value
        End Set
    End Property

End Class

Am I going completely the wrong way about storing the data after importing from a text file?

I am new to VB.NET and still learning the basics but I find it much easier to learn by playing around before hitting the massive books!

Answer 1

Working example:

Dim myurls As New List(Of Test)
myurls.Add(New Test("http://link1.com/", 1))
myurls.Add(New Test("http://link2.com/", 0))
myurls.Add(New Test("http://link3.com/", 0))

Dim result = From t In myurls Where t.Active = 1

For Each testitem As Test In result
    MsgBox(testitem.URL)
Next

By the way, LINQ is magic. You can shorten your loading/parse code to 3 rows of code:

Dim Lines() = IO.File.ReadAllLines("myfile.txt")
Dim myurls As List(Of Test) = (From t In lines Select New Test(Split(t, " - ")(0), Split(t, " - ")(1))).ToList
DataGridViewX1.DataSource = myurls

The first line reads all lines in the file to an array of strings.
The second line splits each line in the array, and creates a test-item and then converts all those result items to an list ( of Test).

Of course this could be misused to sillyness by making it to a one-row:er:

DataGridViewX1.DataSource = (From t In IO.File.ReadAllLines("myfile.txt") Select New Test(Split(t, " - ")(0), Split(t, " - ")(1))).ToList

Wich would render your load function to contain only following 4 rows:

If OpenFileDialog1.ShowDialog() = DialogResult.OK Then
        DataGridViewX1.DataSource = (From t In IO.File.ReadAllLines("myfile.txt") Select New Test(Split(t, " - ")(0), Split(t, " - ")(1))).ToList
        LabelX5.Text = ctype(datagridviewx1.datasource,List(Of Test)).Count
End If