Problems reading elements from XML

Question

Hello everyone!! I am working with MediaFire API and I need to read XML online, from a specific request url

I will leave and example of the response, codified in XML, when I load the request_url

<response>
<action>user/get_session_token</action>
<session_token>
1dbfa6bfe8b4fbaf0d9b4df6bb062bfd96380155a439b288181fc6a81338257976eae158683fbee18fb23121ddf2e29f7d8fcc0639f018ac29aa7984d82e9156887312499774e997
</session_token>
<secret_key>2034564729</secret_key>
<time>1406222550.0564</time>
<ekey>2adda8ea02818b0254e86381f7a17901</ekey>
<pkey>0bf5c04f23</pkey>
<result>Success</result>
<current_api_version>1.0</current_api_version>
</response>

I need to read the following elements:

• Session_token
• Time
• Secret_Key

I am using the following code:

Dim reader As XmlTextReader = New XmlTextReader(request_url) 
        While reader.Read
            If reader.NodeType = Xml.XmlNodeType.Element Then
                Select Case reader.Name
                    Case "session_token"
                        session_token = reader.ReadElementContentAsString
                    Case "secret_key"
                        secret_key = reader.ReadElementContentAsString
                    Case "time"
                        time = reader.ReadElementContentAsString
                End Select
            End If
        End While

'session_token; secret_key; time
'all are variables defined as String
'Dim time as String = ""

It's funny because I don't retrieve the value of the element secret_key 

I did some experiences and I added a Breakpoint like in the image

Then I debugged, and guess what!! Any break, witch means my code is not detecting the element "secret_key" and so, don't retrive the element value.

Now, some curious facts!!

This example here, works fine and shows that axially the code I have shown, detects all the elements I am looking for.

Dim reader As XmlTextReader = New XmlTextReader(request_url)
        While reader.Read
            If reader.NodeType = Xml.XmlNodeType.Element Then
                Select Case reader.Name
                    Case "session_token"
                        Msgbox("session token!!")
                    Case "secret_key"
                        Msgbox("Key!!")
                    Case "time"
                        Msgbox("Time!!")
                End Select
            End If
        End While

The three MesageBox are shown!!

Back to the initial code,

While reader.Read
            If reader.NodeType = Xml.XmlNodeType.Element Then
                Select Case reader.Name
                    Case "session_token"
                        session_token = reader.ReadElementContentAsString
                    Case "secret_key"
                        secret_key = reader.ReadElementContentAsString
                    Case "time"
                        time = reader.ReadElementContentAsString
                End Select
            End If
        End While

It looks like after retrive the session_token element value, it setps over the secret_key, and read all the rest of the elements.

Why? Any alternative solution?

---

Meu novo programa (Bloco de Notas) http://hyrokumata-app.blogspot.pt/2012/07/notepad-3-beta.html

Answer 1

Fabio,

That's not the entire XML so without it, it's hard to give you specific help, but in short - I'd encourage you to use LINQ-To-XML to read it (directly via the URL).

It shouldn't be difficult but without seeing the entire XML file, I can't really know.

---

Still lost in code, just at a little higher level.

:-)

Answer 2

Hello,

Using the xml you supplied we can do the following where in this case I have placed the xml into My.Resources as a text file (all that matters is we are dealing with text).

Code

Results

---

Please remember to mark the replies as answers if they help and unmark them if they provide no help, this will help others who are looking for solutions to the same or similar problem.

Answer 3

Fabio,

That's not the entire XML so without it, it's hard to give you specific help, but in short - I'd encourage you to use LINQ-To-XML to read it (directly via the URL).

It shouldn't be difficult but without seeing the entire XML file, I can't really know.

---

Still lost in code, just at a little higher level.

:-)

Sorry Frank, probably that XML is not very well structured but that is the full response I ggrt

You can see that is according with Media fire API CORE documentation. Nothing missing ...

https://www.mediafire.com/developers/core_api/unversioned/

I have a question ... I don't know very well the structure of a XML file but I was thinking in something. Because I know what exactly elements I need, is not there a way to retrieve the value by specifying the "path", I mean 

response/session_token

?

---

Meu novo programa (Bloco de Notas) http://hyrokumata-app.blogspot.pt/2012/07/notepad-3-beta.html

Answer 4

Hello,

Using the xml you supplied we can do the following where in this case I have placed the xml into My.Resources as a text file (all that matters is we are dealing with text).

Code

Results

---

Please remember to mark the replies as answers if they help and unmark them if they provide no help, this will help others who are looking for solutions to the same or similar problem.

Interesting ... I have to test it and try to understand that code. For sure, I will need to download the online response as a text file to somewhere location on hard drive and then work with it. I can't add it to My.Resources

I am just thinking if is good idea converting a XML to a text file. Is there no problem?

---

Meu novo programa (Bloco de Notas) http://hyrokumata-app.blogspot.pt/2012/07/notepad-3-beta.html

Answer 5

Windows Communication Foundation is made with mainly your problem in mind.

Take a look at it.

http://msdn.microsoft.com/en-us/library/ms731190(v=vs.110).aspx

---

Success
Cor

Answer 6

Fabio,

That's not the entire XML so without it, it's hard to give you specific help, but in short - I'd encourage you to use LINQ-To-XML to read it (directly via the URL).

It shouldn't be difficult but without seeing the entire XML file, I can't really know.

---

Still lost in code, just at a little higher level.

:-)

Hello Frank!!

I heard your sugesttion about using LINQ, well I tried and that solved my problem :) Thanks

Dim root As XElement = XDocument.Load(request_url).Root
        session_token = root.Element("session_token").Value
        secret_key = root.Element("secret_key").Value
        time = root.Element("time").Value

Source: [http://stackoverflow.com/questions/11581692/how-to-read-xml-elements-in-vb-net]

Answer 7

Hello Frank!!

I heard your sugesttion about using LINQ, well I tried and that solved my problem :) Thanks

Dim root As XElement = XDocument.Load(request_url).Root
        session_token = root.Element("session_token").Value
        secret_key = root.Element("secret_key").Value
        time = root.Element("time").Value

Source: [http://stackoverflow.com/questions/11581692/how-to-read-xml-elements-in-vb-net]

That's not how I would have done it but if it works for you then great! :)

---

Still lost in code, just at a little higher level.

:-)

Answer 8

Hello,

Using the xml you supplied we can do the following where in this case I have placed the xml into My.Resources as a text file (all that matters is we are dealing with text).

Code

Results

---

Please remember to mark the replies as answers if they help and unmark them if they provide no help, this will help others who are looking for solutions to the same or similar problem.

Interesting ... I have to test it and try to understand that code. For sure, I will need to download the online response as a text file to somewhere location on hard drive and then work with it. I can't add it to My.Resources

I am just thinking if is good idea converting a XML to a text file. Is there no problem?

---

Meu novo programa (Bloco de Notas) http://hyrokumata-app.blogspot.pt/2012/07/notepad-3-beta.html

The concept is to read in a string containing valid xml into a XDocument. Does not matter where the data comes from, in my example think of the text file as mocked data that in a real app would had come from say downloading a file from the web etc.

---

Please remember to mark the replies as answers if they help and unmark them if they provide no help, this will help others who are looking for solutions to the same or similar problem.

Answer 9

I am just thinking if is good idea converting a XML to a text file. Is there no problem?

Fabio,

Please understand that an XML file already *is* a text file! It's just specially structured text but it's text nevertheless.

What Kevin showed used LINQ, and it's not easy to catch on to at first, but it's very effective once you get the hang of it.

*****

Let me give you a more simple one to follow, even though this will also be somewhat confusing at first. I took the XML from what you posted originally and I put it into a text file that I named "Example.xml" and put that on my desktop. You might want to do the same so you can try this:

Option Strict On
Option Explicit On

Imports System.IO.Path

Public Class Form1

    Private Sub Form1_Load(ByVal sender As System.Object, _
                           ByVal e As System.EventArgs) _
                           Handles MyBase.Load

        Dim dt As String = My.Computer.FileSystem.SpecialDirectories.Desktop
        Dim xmlFilePath As String = Combine(dt, "Example.xml")

        GetDataFromXML(xmlFilePath)

    End Sub



    Private Sub GetDataFromXML(ByVal urlOrFilePath As String)

        Try
            Dim xDoc As XElement = XElement.Load(url)

            Dim action As String = xDoc...<action>.Value
            Dim sessionToken As String = xDoc...<session_token>.Value
            Dim secretKey As String = xDoc...<secret_key>.Value
            Dim time As String = xDoc...<time>.Value
            Dim eKey As String = xDoc...<ekey>.Value
            Dim pKey As String = xDoc...<pkey>.Value
            Dim result As String = xDoc...<result>.Value
            Dim currentApiVersion As String = xDoc...<current_api_version>.Value


            Stop

        Catch ex As Exception
            MessageBox.Show("An error occurred:" & _
                            vbCrLf & vbCrLf & ex.Message, _
                            "Error Reading XML", _
                            MessageBoxButtons.OK, _
                            MessageBoxIcon.Warning)
        End Try

    End Sub

End Class

Notice in the sub that first it reads the XML file using XElement.Load.

Because of the structure (this is why I wanted to see the whole thing - there's no telling how many levels there actually are), since it has a parent - <response> - then even though that's read, you won't use it directly; instead read the children of <response> like I show above.

The odd looking ellipsis, well that's how LINQ-To-XML works (they're called axis accessors by the way) and of course, per item, you tell it specifically that you want to get the value of that element.

Does that help some?

---

Still lost in code, just at a little higher level.

:-)