How to parse XML in VBA and retrieve specific values

Question

I\'ve already spent two weeks searching unsuccessfully how to parse one specific XML and fetch just few values. I already tried every single code on internet until I found o

Answer 1

I've reached this solution, mixing the two answers, and sharing the code to help others.

First I set the property and then used the iteration to retrieve the values I needed, I don't know if this is the best solution, since I can't control the XML structure and if they change their file I'll need to return to this code.

I tried to work in a "Safety Line" to avoid any mistake in the output, but no problem for me to double check since I have access to the data itself.

If node.childNodes(0).text = "Production" And node.childNodes(6).text = "Argentina" Then

To ensure that the name and response will bring whatever I want.

Public Sub test_3()
    Dim xmlDoc As MSXML2.DOMDocument60
    Dim URL As String, APIkey As String

    APIkey = "8DB688F8-1E22-4031-B581-59C221ECDDA6"

    URL = "https://apps.fas.usda.gov/PSDOnlineDataServices/api/CommodityData/GetCommodityDataByYear?commodityCode=2222000&marketYear=2018"

    Set xmlDoc = New MSXML2.DOMDocument60

    With CreateObject("MSXML2.XMLHTTP")
        .Open "GET", URL, False
        .SetRequestHeader "Accept", "text/xml"
        .SetRequestHeader "API_KEY", APIkey
        .Send
        xmlDoc.loadXML .ResponseText
        xmlDoc.SetProperty "SelectionNamespaces", "xmlns:r='http://schemas.datacontract.org/2004/07/PSDOnline.DataServices.Models'"
    End With

    Dim node As IXMLDOMElement, r As Long

    For Each node In xmlDoc.selectNodes("//r:CommodityData")
        If node.childNodes(0).text = "Production" And node.childNodes(6).text = "Argentina" Then
        r = r + 1
        Debug.Print node.childNodes(0).text
        Debug.Print node.childNodes(6).text
        Debug.Print node.LastChild.text
        'With ActiveSheet
            '.Cells(r, 1) = node.childNodes(0).text
            '.Cells(r, 2) = node.childNodes(6).text
            '.Cells(r, 3) = node.LastChild.text
        'End With
        End If
    Next
End Sub

This solution return the following response in the DEBUGGER:

Production

Argentina

55300.0000

Exactly what I wanted.

Thanks again for the time and for sharing knowledge.

Answer 2

It's a namespace issue I think. There are people more familiar with this who can likely fix how to add properly and then reference. I did try adding the two namespaces with the usual syntax .setProperty "SelectionNamespaces", namespace but still failed to set objects so guess I did something wrong.

An interim, less robust solution is as follows:

Option Explicit
Public Sub test()
    Dim xmlDoc As MSXML2.DOMDocument60
    Dim URL As String, APIkey As String

    APIkey = "key"

    URL = "https://apps.fas.usda.gov/PSDOnlineDataServices/api/CommodityData/GetCommodityDataByYear?commodityCode=2222000&marketYear=2018"

    Set xmlDoc = New MSXML2.DOMDocument60

    With CreateObject("MSXML2.XMLHTTP")
        .Open "GET", URL, False
        .SetRequestHeader "Accept", "text/xml"
        .SetRequestHeader "API_KEY", APIkey
        .Send
        xmlDoc.LoadXML .responseText
    End With

    Dim node As IXMLDOMElement, r As Long
    For Each node In xmlDoc.SelectNodes("/*[name()='ArrayOfCommodityData']/*[name()='CommodityData']")
        r = r + 1
        With ActiveSheet
            .Cells(r, 1) = node.ChildNodes(0).Text
            .Cells(r, 2) = node.ChildNodes(6).Text
            .Cells(r, 3) = node.ChildNodes(11).Text
        End With
    Next
End Sub

Answer 3

There are two separate issues here.

MSXML2 has issues using XPath when the XML document has a default namespace - see here for details. At the start of the downloaded document from the USDA site, there are some namespace declarations:

<ArrayOfCommodityData xmlns:i="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://schemas.datacontract.org/2004/07/PSDOnline.DataServices.Models">

There are two namespaces declared here. One with the prefix i and a default namespace that covers any element which does not have a namespace prefix. If you look at a "CalendarYear" entry in the XML document - <CalendarYear i:nil="true" /> - then you can see that "CalendarYear" is in the default namespace whereas "nil" is in the "i" namespace.

To make MSXML2 work with default namespaces, you have to declare a namespace which has the same URI as the default namespace. This is done using the SelectionNamespaces property of the XML document, like this:

xmlDoc.SetProperty "SelectionNamespaces", "xmlns:r='http://schemas.datacontract.org/2004/07/PSDOnline.DataServices.Models'"

I chose r as the namespace but the name you choose is irrelevant - it just has to be different from any other namespaces in the document.

This leads on to the second problem. You are using getElementsByTagName which just takes a tag name as a parameter but you are passing in an XPath string. To deal with an XPath string, you need to use SelectNodes instead and you need to use the namespace we added, like this:

Set xmlNodeList = xmlDoc.SelectNodes("//r:AttributeDescription")