Read lines between <text></text> and load them into a combo box?

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Im making an RSS Feed reader, in which I categorize feeds, and per category has a list of different RSS Feeds that the user will be able to customize. I want categorize all the feeds inside a single text file, for easy editing, and get every line between <category1></category1>injected into a combo box. Example:

<category1>
feed1
feed2
feed3
</ccategory1>
<category2>
feed4
feed5
</category2>

With the combobox for Category1 only recieiving the text:
feed1
feed2
feed3

While the same combobox is filled with Category 2 upon selection, looking like this:
feed4
feed5

What I have tried:

Google, never been good with StreamReaders/Writers

Posted 1-May-20 23:39pm

Member 12111727

Updated 3-May-20 2:35am

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Comments

MadMyche 2-May-20 7:37am

It would be helpful to see the code... makes it a lot easier to see what may be wrong with it

Richard MacCutchan 2-May-20 7:39am

If that is real XML then you can use the XMLDocument class to read the content. If it is just a text file with XML-like keywords then use the StreamReader class and check for the keyword items as you read each line. What is the actual problem?

Member 12111727 2-May-20 7:58am

I have no problems with my XML streamer, its the text file streaming. Im not sure how to find a chunck of text, in this case: a chunck between <category1> and <_/category1>

Would it be easier to write and read to an xml rather than a text file?

Richard MacCutchan 2-May-20 8:01am

It may be easier to write it to XML but it all depends on what you are trying to do. Reading a simple text file and checking for keyword entries of the form shown above is a fairly simple process.

Member 12111727 2-May-20 8:04am

Thats all I want to do. Basically I have a Combo box and a DataviewGrid. My RSSParser class takes care of translating known RSS feeds and listing the items in the DataViewGrid, All i want to do, is be able to select with the combo box, which feed I want to populate the GridView with.

But I also want the user to be able to customize which Feeds are available, hence the textfile with categories and feed links

2 solutions

Solution 2

You don't really need to deal with stream reader:

VB.NET

Public Shared Function GetFeeds(ByVal doc As XmlDocument, ByVal category As String) As String()

   If (doc Is Nothing) Then 
      Throw New ArgumentNullException(NameOf(doc))
   End If

   Dim node As XmlElement = CType(doc.DocumentElement.SelectSingleNode("//" + category), XmlElement)

   If (node IsNot Nothing) Then
      Return node.InnerText.Split(New String() { Environment.NewLine }, StringSplitOptions.RemoveEmptyEntries)
   Else
      Return New String() { }
   End If

End Function

'' Usage
Dim doc As XmlDocument = XmlDocument.Load("path\to\your\xml\file")
Dim feeds1 As String() = GetFeeds(doc, "category1")
Dim feeds2 As String() = GetFeeds(doc, "category2")

comboBox1.Items.AddRange(feeds1)
combobox2.Items.AddRange(feeds2)

There may be some mistakes as I used a c# to vb.net converter (I don't write vb.net code anymore), but this is a concise way to get your combobox items from your xml file.

Posted 2-May-20 2:04am

phil.o

Comments

Member 12111727 2-May-20 8:10am

Only issue I am having is that XmlDocument doesnt have a .Load function

phil.o 2-May-20 8:25am

You may have to add a reference to System.Xml.dll.
The Load method really exists:
XmlDocument.Load Method

Member 12111727 2-May-20 9:03am

Ok, it fixed that, but now its just not working, no errors. I had to slightly odify the code because Document Element wasnt workin, so i switched it to Elements


Public Function GetFeeds(ByVal FeedsDoc As XDocument, ByVal category As String) As String()

        If (FeedsDoc Is Nothing) Then
            Throw New ArgumentNullException(NameOf(FeedsDoc))
        End If

        Dim node As XmlElement = CType(FeedsDoc.Elements("/category/" + category + "/link"), XmlElement)

        If (node IsNot Nothing) Then
            Return node.InnerText.Split(New String() {Environment.NewLine}, StringSplitOptions.RemoveEmptyEntries)
        Else
            Return New String() {}
        End If

    End Function

Member 12111727 2-May-20 9:05am

My RSS Feed XML


<category>
  <earthquake>
      <link>https://www.volcanodiscovery.com/volcanonews.rss</link>
  </earthquake>
  <volcano>
      <link>https://www.volcanodiscovery.com/volcanonews.rss</link>
  </volcano>
  <hurricane>
      <link>https://www.volcanodiscovery.com/volcanonews.rss</link>
  </hurricane>
  <tsunami>
      <link>https://www.volcanodiscovery.com/volcanonews.rss</link>
  </tsunami>
  <space>
      <link>https://www.volcanodiscovery.com/volcanonews.rss</link>
  </space>
  <disease>
      <link>https://www.volcanodiscovery.com/volcanonews.rss</link>
  </disease>
  <custom>
      <link>https://www.volcanodiscovery.com/volcanonews.rss</link>
  </custom>
</category>

phil.o 2-May-20 9:20am

I wrote XmlDocument, you wrote XDocument. Those are distinct objects whose usages are also distinct.

Member 12111727 3-May-20 5:15am

Ok, So I reverted back to your original. The error for XmlDocument.Load("myfile.xml") is "Referrence to a non-shared member requires an object referrence"

phil.o 3-May-20 5:25am

My bad; try

Dim doc As New XmlDocument()
doc.Load("path\to\your\xml\file")

instead.

Member 12111727 3-May-20 5:41am

Nope. Again, no errors but its preventing my DataGridView from filling

Member 12111727 3-May-20 6:25am

So I scarpped the whole thing and replaced it with this:

Public Function FillFeedList(combo As ComboBox, category As String)
        'Connect to Internal Feed Database
        Dim path As String = "RSSFeeds.xml"
        Dim feedDoc As New XmlDocument()
        feedDoc.Load(path)

        Dim selectedCategory As XmlNodeList = feedDoc.SelectNodes("category/" + category)
        Dim i As Integer = 0
        For Each node In selectedCategory.Item(i)
            Dim feedLink As XmlNode = selectedCategory.Item(i).SelectSingleNode("link")
            If feedLink IsNot Nothing Then
                'combo.Items.Add(feedLink.InnerText)
                combo.DataSource = (From element In feedLink Select element.Value).ToList()
            Else
                combo.Text = Nothing
            End If
        Next

        i += 1
        Return Nothing


    End Function

the only problem, is it still only loads one feed, the first one.
I copied a bunch of links into the eq feed like this:

<?xml version="1.0"?>
<category>
  <earthquake>
      <link>https://www.volcanodiscovery.com/volcanonews.rss</link>
      <link>https://www.volcanodiscovery.com/volcanonews.rss</link>
      <link>https://www.volcanodiscovery.com/volcanonews.rss</link>
      <link>https://www.volcanodiscovery.com/volcanonews.rss</link>
  </earthquake>
  <volcano>
      <link>https://www.volcanodiscovery.com/volcanonews.rss</link>
  </volcano>
  <hurricane>
      <link>https://www.volcanodiscovery.com/volcanonews.rss</link>
  </hurricane>
  <tsunami>
      <link>https://www.volcanodiscovery.com/volcanonews.rss</link>
  </tsunami>
  <space>
      <link>https://www.volcanodiscovery.com/volcanonews.rss</link>
  </space>
  <disease>
      <link>https://www.volcanodiscovery.com/volcanonews.rss</link>
  </disease>
  <custom>
      <link>https://www.volcanodiscovery.com/volcanonews.rss</link>
  </custom>
</category>

phil.o 3-May-20 6:49am

It selects only the first one because that is what you ask for with your i variable, which is initialized to zero (the first item), and is incremented outside the loop: your loop won't ever see another value for i than zero. If you want an index-based access, then don't use a ForEach loop, but a plain For loop instead:

Dim selectedCategory As XmlNodeList = feedDoc.SelectNodes("category/" + category)
Dim elements As New List(Of String)
For i As Integer = 0 To selectedCategory.Count - 1
   Dim feedLink As XmlNode = selectedCategory.ItemOf(i)
   If feedLink IsNot Nothing Then
      elements.Add(feedLink.InnerText)
   End If
Next
combo.DataSource = elements

Member 12111727 3-May-20 6:59am

Sooooo close. Thank you, but instead of habing individual items that you can choose from in the Combobox, it slaps all items into 1

phil.o 3-May-20 7:01am

Then maybe try

combo.Items.AddRange(elements.ToArray())

instead.

Member 12111727 3-May-20 7:05am

Its says "Value of Type List(Of String) cannot be converted to Object()

phil.o 3-May-20 7:10am

Corrected. You will need to import System.Linq namespace for the ToArray() method.

Member 12111727 3-May-20 7:15am

I already tried that, no dice.

phil.o 3-May-20 7:25am

Weird, because elements.ToArray() will return a String() (a string array), which is inherently an Object() (an object array).

Member 12111727 3-May-20 7:28am

I mean it fixed the error, but it still shows up as one item in the cmombo box

phil.o 3-May-20 7:40am

Then you should begin using the debugger and watch for the contents of the elements list. Do you need help on how to conduct a debug session?

Member 12111727 3-May-20 7:45am

Yes lol.

phil.o 3-May-20 7:55am

Here are a couple of links to get you started with debugging:
Tutorial: Learn to debug Visual Basic code using Visual Studio
Breakpoints and Debugging Tools
Knowing how to debug is an essential skill; it allows to investigate your code to see why it does not produce the results you are expecting.

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Member 12111727 · Accepted Answer · 2020-05-03T02:37:00

I Got it. Turns out the problem was how I was calling and using my nodes and xmlDocument

Public Function FillFeedList(combo As ComboBox, category As String)
        'Connect to Internal Feed Database
        Dim path As String = "RSSFeeds.xml"
        Dim feedDoc As New XmlDocument()
        feedDoc.Load(path)

        Dim selectedCategory As XmlNode = feedDoc.SelectSingleNode("category/" + category)
        Dim elements As New List(Of String)
        For i As Integer = 0 To selectedCategory.ChildNodes.Count
            Dim feedLink As XmlNode = selectedCategory.ChildNodes.Item(i)
            If feedLink IsNot Nothing Then
                elements.Add(feedLink.InnerText)
            End If
        Next
        combo.Items.AddRange(elements.ToArray())
        Return Nothing


    End Function

Read lines between <text></text> and load them into a combo box?

2 solutions

Solution 2

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Read lines between <text></text> and load them into a combo box?

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