Question

i have some big size xml file (>500mb) like the one bellow.

    <?xml version="1.0" encoding="UTF-8"?>
<ChangeRequests Count="" ID="" Update="">
    <Requests>
        <Request Type="Insert" Method="Customer">
            <Country>xXx</Country>
            <Window>10</Window>
            <Door>11</Door>
            <Id>88747</Id>
            <Name>Lore Ipsum</Name>
            <FirstName />
            <OwnerFirstName />
            <OwnerName />
            <OwnerBirthday />
            <CompanyName1 />
            <CompanyName1 />
        </Request>
            <Request Type="Insert" Method="Customer">
            <Country>xXx</Country>
            <Window>10</Window>
            <Door>11</Door>
            <Id>444544</Id>
            <Name>Lazy Dog</Name>
            <FirstName />
            <OwnerFirstName />
            <OwnerName />
            <OwnerBirthday />
            <CompanyName1 />
            <CompanyName1 />
        </Request>
            <Request Type="Insert" Method="Customer">
            <Country>xXx</Country>
            <Window>10</Window>
            <Door>11</Door>
            <Id>444544</Id>
            <Name>Lazy Dog</Name>
            <FirstName />
            <OwnerFirstName />
            <OwnerName />
            <OwnerBirthday />
            <CompanyName1 />
            <CompanyName1 />
            </Request>
    </Requests>
</ChangeRequests>

i would like to read the first Request node and add to a combobox all of his childs without having to read other part of the xml. the code that i came up with is the one below but it goes through all of them and it will add to combo box alot of duplicate values.

  Dim xml_doc As New XmlDocument
    Dim xmlReader As New XmlTextReader(TextBox1.Text)
    Dim arr As New ArrayList
    xmlReader.MoveToContent()
    xmlReader.ReadToFollowing("Request")
    While xmlReader.Read()
        Select Case xmlReader.NodeType
            Case XmlNodeType.Element
                ComboBox1.Items.Add("<" + xmlReader.Name & ">")
                Exit Select
        End Select
    End While

Answer 1

如果您只想阅读第一个Request元素的子元素，可以检查Request元素的结尾并退出循环：

While xmlReader.Read()
    If xmlReader.NodeType = XmlNodeType.EndElement AndAlso xmlReader.Name = "Request" Then
        Exit While
    End If
    Select Case xmlReader.NodeType
        ' ...

对于任何重复的子元素，这仍然会留下重复的内容，例如： <CompanyName1> ...但也许那没关系。如果你还想对它们进行重复数据删除，那么LINQ的Distinct方法可以帮到那里：

Dim xmlReader As New XmlTextReader(TextBox1.Text)
xmlReader.MoveToContent()
xmlReader.ReadToFollowing("Request")
' Collect the names in a List
Dim elementNames As New List(Of String)()
While xmlReader.Read()
    Select Case xmlReader.NodeType
        Case XmlNodeType.Element
            elementNames.Add("<" + xmlReader.Name & ">")
            Exit Select
    End Select
End While
' Add distinct values to the ComboBox
ComboBox1.Items.AddRange(elementNames.Distinct().ToArray())

unique values from XML to combobox

1 个答案: