How to get attribute value from XML using VB.NET?

Question

I have the following xml:

    <?xml version="1.0" encoding="UTF-8"?>
    <gesmes:Envelope xmlns:gesmes="http://www.gesmes.org/xml/2002-08-01" xmlns="http://www.ecb.int/vocabulary/2002-08-01/eurofxref">
    <gesmes:subject>Reference rates</gesmes:subject>
    <gesmes:Sender>
    <gesmes:name>European Central Bank</gesmes:name>
    </gesmes:Sender>
    <Cube>
    <Cube time='2016-09-12'>
        <Cube currency='USD' rate='1.1226'/>
        <Cube currency='JPY' rate='114.38'/>
    </Cube>
    </Cube>
    </gesmes:Envelope>

I want to get attribute value of each currency. For now I am using this but it doesn't work:

    Dim xmlTree1 As New XmlDocument()
    xmlTree1.Load("C:\\download\eurofxref-daily.xml")

    Dim currencyUSD As String = xmlTree1.SelectSingleNode("/gesmes:Envelope/Cube/Cube/Cube[@currency='USD']/@rate").Value
    Dim currencyJPY As String = xmlTree1.SelectSingleNode("/gesmes:Envelope/Cube/Cube/Cube[@currency='JPY']/@rate").Value

Please post the xml you are attempting to extract from and the code where you create xmlTree1. — FloatingKiwi
– FloatingKiwi, Commented Sep 14, 2016 at 10:25
I have put the code of the XML and code where I create xmlTree1. — SeaSide
– SeaSide, Commented Sep 14, 2016 at 10:50
The gesmes prefix needs to be registered with the namespace. See this article on using the namespace manager support.microsoft.com/en-us/kb/318545 — FloatingKiwi
– FloatingKiwi, Commented Sep 14, 2016 at 10:53

Heinzi · Accepted Answer · 2016-09-16 10:00:43Z

1

An alternative is to use the awesome Linq-to-XML features of VB.NET (Framework 3.5 and higher):

Imports <xmsns:xref="http://www.ecb.int/vocabulary/2002-08-01/eurofxref">

...

Dim xdoc = XDocument.Load("C:\kursna_standalone\download\eurofxref-daily.xml")
Dim cubes = xdoc.Root.<xref:Cube>.<xref:Cube>
Dim currencyUSD = cubes.Where(Function(x) x.currency = "USD").@rate
Dim currencyJPY = cubes.Where(Function(x) x.currency = "JPY").@rate

_{(Note: All my VB code examples assume that Option Strict and Option Infer are active).}

edited Sep 16, 2016 at 10:00

answered Sep 15, 2016 at 7:00

Heinzi

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3 Comments

SeaSide Over a year ago

Thank you for your answer Heinzi. This will work with NET.Framework 4 but currently I am using NET.Framework 2 and it doesn't recognize XDocument.

Heinzi Over a year ago

@SeaSide: .NET Framework 3.5 should work as well, if that is an option for you.

SeaSide Over a year ago

That's good to know, because I will certainly have to upgrade on the newer. Thank you.

SeaSide · Accepted Answer · 2016-09-16 09:26:35Z

1

I am using the following code to get the value from xml and it works:

 Dim xmlTree1 As New XmlDocument()
 xmlTree1.Load("C:\\kursna_standalone\download\eurofxref-daily.xml")

 Dim xmlnsManager1 As New System.Xml.XmlNamespaceManager(xmlTree1.NameTable)
 xmlnsManager1.AddNamespace("gm1", "http://www.ecb.int/vocabulary/2002-08-01/eurofxref")

 Dim currencyUSD As String = xmlTree1.SelectSingleNode("//gm1:Cube/gm1:Cube/gm1:Cube[@currency='USD']/@rate", xmlnsManager1).Value
 Dim currencyJPY As String = xmlTree1.SelectSingleNode("//gm1:Cube/gm1:Cube/gm1:Cube[@currency='JPY']/@rate", xmlnsManager1).Value

edited Sep 16, 2016 at 9:26

answered Sep 15, 2016 at 6:41

SeaSide

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