How to select XML child node using its baseName in

2019-06-21 23:42发布

问题:

I'm a little bit stuck with the following: I try to get currency rates from the local bank website to Excel using VBA - mostly for XML parsing practice, I'd say this is my first serious attempt.

After several hours of googling and reading related SO questions I got the more or less working solution, but I'd like to optimize it for better XML understating. So far so good, the question is:

<LIST_RATE>
    <RATE ISO="EUR" Code="978">
        <TITLE>Евро</TITLE>
        <CODE>978</CODE>
        <ISO>EUR</ISO>
        <DATE>Thu, 31 Jan 2013 09:00:00 GMT</DATE>
        <BUY>11550.0000</BUY>
        <SELL>11820.0000</SELL>
        <QUANTITY>1</QUANTITY>
    </RATE>
    <RATE ISO="RUB" Code="643">
        <TITLE>Российский рубль</TITLE>
        <CODE>643</CODE>
        <ISO>RUB</ISO>
        <DATE>Thu, 31 Jan 2013 09:00:00 GMT</DATE>
        <BUY>279.0000</BUY>
        <SELL>292.0000</SELL>
        <QUANTITY>1</QUANTITY>
    </RATE>
    <RATE ISO="USD" Code="840">
        <TITLE>Доллар США</TITLE>
        <CODE>840</CODE>
        <ISO>USD</ISO>
        <DATE>Thu, 31 Jan 2013 09:00:00 GMT</DATE>
        <BUY>8570.0000</BUY>
        <SELL>8710.0000</SELL>
        <QUANTITY>1</QUANTITY>
    </RATE>
</LIST_RATE>

For the above XML part (just in case - this is the link to full XML: http://www.priorbank.by/CurratesExportXml.axd?channel=9) I'm looping through RATE child nodes of LIST_RATE node using the following code:

For Each RATE_Node In LIST_RATE_Node.ChildNodes
    CurrencyCode = RATE_Node.ChildNodes.Item(2).Text 'ISO node
    RateValue = CSng(Replace(RATE_Node.ChildNodes.Item(4).Text, ".", ",")) 'BUY node
    [rest of code]
Next

The code is working fine, but I'd like to select RATE node child nodes somehow using their names instead of Item(#). I tried selectSingleNode, but I'm not at all familiar with XPath, and the notation that I used always returned the very first <RATE ISO="EUR" Code="978"> values. getElementsByTagName returns the whole bunch of nodes, and so on.

I read a lot of related SO questions, but still stuck. I'm pretty sure the solution is simple - I just need to make all the ends meet. Any advice or guidance to the right direction will be highly appreciated. Thanks in advance!

回答1:

    Option Explicit

    Private Const xml As String = "<LIST_RATE>" & _
        "<RATE ISO='EUR' Code='978'>" & _
            "<TITLE>????</TITLE>" & _
            "<CODE>978</CODE>" & _
            "<ISO>EUR</ISO>" & _
            "<DATE>Thu, 31 Jan 2013 09:00:00 GMT</DATE>" & _
            "<BUY>11550.0000</BUY>" & _
            "<SELL>11820.0000</SELL>" & _
            "<QUANTITY>1</QUANTITY>" & _
        "</RATE>" & _
    "</LIST_RATE>"

    Sub test()
        Dim xmlDocument As MSXML2.DOMDocument60
        Set xmlDocument = New DOMDocument60

        If Not xmlDocument.LoadXML(xml) Then
            Err.Raise xmlDocument.parseError.ErrorCode, , xmlDocument.parseError.reason
        End If

        Dim listRateNode As IXMLDOMNode
        Dim rateNode As IXMLDOMNode
        Dim isoNode As IXMLDOMNode
        For Each listRateNode In xmlDocument.ChildNodes
            For Each rateNode In listRateNode.ChildNodes
                Set isoNode = rateNode.SelectSingleNode("ISO")
            Next
        Next

        Set isoNode = Nothing
        Set isoNode = xmlDocument.SelectSingleNode("/LIST_RATE/RATE[ISO='EUR']/ISO")
    End Sub

SelectSingleNode should work. If SelectSingleNode is used on RATE_NODE then use just rateNode.SelectSingleNode("ISO"). On the xml-document u can use xmlDocument.SelectSingleNode("/LIST_RATE/RATE[ISO='EUR']/ISO") to find iso node with value EUR. Is this helpfull for u?