使用LINQ将元素更新为XML? [英] Update elements using LINQ to XML?

问题描述

我有以下XML，但是我很难弄清楚如何使用LINQ to XML直接更新元素:

I have the following XML, but I am having a hard time figuring out how to update the elements directly using LINQ to XML:

XElement settings = XElement.Parse (
@"<?xml version='1.0' encoding='utf-8'?>
<soapenv:Envelope xmlns:soapenv='http://schemas.xmlsoap.org/soap/envelope/' 
                  xmlns:xsd='http://www.w3.org/2001/XMLSchema'
                  xmlns:xsi='http://www.w3.org/2001/XMLSchema-instance'    
                  xmlns:wsa='http://schemas.xmlsoap.org/ws/2004/08/addressing'
                  xmlns:wsse='http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-wssecurity-secext-1.0.xsd' 
                  xmlns:wsu='http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-wssecurity-utility-1.0.xsd'>
<soapenv:Header>
<wsse:Security soapenv:mustUnderstand='1'> 
    <wsse:UsernameToken wsu:Id='UsernameToken-72135529'> 
        <wsse:Username>{USERNAME}</wsse:Username> 
        <wsse:Password Type='http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-username-token-profile-1.0#PasswordText'>{PASSWORD}</wsse:Password> 
    </wsse:UsernameToken> 
 </wsse:Security> 
    <wsa:MessageID>{MESSAGEID}</wsa:MessageID> 
    <wsa:To>{TO}</wsa:To> 
    <wsa:Action>{ACTION}</wsa:Action> 
    <wsa:From> 
    <wsa:Address>{ADDRESS}</wsa:Address> 
</wsa:From> 
   </soapenv:Header>
   <soapenv:Body>
{BODY}
  </soapenv:Body>
</soapenv:Envelope>");

例如，在上面，我要访问每个具有placholder值{}的元素并更新文本.在这种情况下，XElement.Parse()是否正确?我最有可能先将其加载到XDocument中，然后再更新元素.另外，如何更新属性，例如Password上的Type属性?

For example, in the above, I want to access each element that has placholder value {} and update the text. Is doing XElement.Parse() correct in this scenario? I am most likely going to load it into and XDocument first and then update the elements. Also, how could I update attributes, like the Type attribute on Password?

试图获取用户名，但它说这是一个InvalidOperationException.

Trying to get to Username, but it says it is an InvalidOperationException.

XNamespace xmlns = "http://schemas.xmlsoap.org/soap/envelope/";
XNamespace wsa = "http://schemas.xmlsoap.org/ws/2004/08/addressing";
XNamespace wsse = "http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-wssecurity-secext-1.0.xsd";
XNamespace wsu = "http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-wssecurity-utility-1.0.xsd";

var textElement = settings.Elements(xmlns + "Envelope").
                           Elements(xmlns + "Header").
                           Elements(wsse + "Security").
                           Elements(wsse + "UsernameToken").
                           Elements(wsse + "Username").Single();

还是我吗?如果我知道元素的确切位置，并且例如想更新或删除xmlns:wsa，使用XPath看起来是否更简单?

Also, is it just me or does using XPath seem simpler if I know the exact position of the elements and if I wanted to update or remove xmlns:wsa for example, how would that be achieved?

推荐答案

可以做到

var elements = settings.DescendantNodes().OfType<XText>().Where(p => p.Value.StartsWith("{") && p.Value.EndsWith("}"));

foreach (var node in elements)
{
    // This is an example of manipulation. It will simply remove the {}
    node.Value = node.Value.Substring(1, node.Value.Length - 2);
}

您可以直接在for循环中移动Where条件，例如

You could move the Where condition directly in the for cycle, like

var elements = settings.DescendantNodes().OfType<XText>();

foreach (var node in elements.Where(p => p.Value.StartsWith("{") && p.Value.EndsWith("}")))
{
    // This is an example of manipulation. It will simply remove the {}
    node.Value = node.Value.Substring(1, node.Value.Length - 2);
}

查找XText节点的说明来自 C#中的XElement值

请注意，您需要添加缺少的名称空间:

Note that you'll need to add the missing namespaces:

xmlns:wsse='something' xmlns:wsa='somethingelse' xmlns:wsu='somethingelseelse'

或XElement.Parse会断开；

如果您要更新一个名称已知的元素:

If you want to update a single element of which you know the name:

XNamespace wsa = "somethingelse"; // Here you must put the namespace!

var textElement = settings.Descendants(wsa + "MessageID").Single(); // If there is only one Message ID to change (0 or > 1 MessageID will make Single throw), .First() if you are only interested in the first one
textElement.Value = "MessageID"; // Changed!

或

var textElements = settings.Descendants(wsa + "MessageID") // If there are multipleMessage ID to change

foreach (var textElement in textElements)
{
    textElement.Value = "MessageID"; // Changed!
}

请注意，这些变体将更改第一个/所有wsa:MessageID，而忽略其位置.

Be aware that these variants will change the first/all the wsa:MessageID, ignoring their position.

或者如果您知道节点的确切路径"，请使用

or if you know the exact "path" to your node, use something like

var textElements = settings.Elements(name1).Elements(name2)...

，然后使用Single()，.First()或foreach

一小段示例代码:

XElement settings = XElement.Parse(
@"<?xml version='1.0' encoding='utf-8'?>
<soapenv:Envelope xmlns:soapenv='http://schemas.xmlsoap.org/soap/envelope/' xmlns:wsa='http://schemas.xmlsoap.org/ws/2004/08/addressing' xmlns:wsse='http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-wssecurity-secext-1.0.xsd' xmlns:wsu='http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-wssecurity-utility-1.0.xsd'>
    <soapenv:Header>
        <wsse:Security soapenv:mustUnderstand='1'> 
            <wsse:UsernameToken wsu:Id='UsernameToken-72135529'> 
                <wsse:Username>{USERNAME}</wsse:Username> 
                <wsse:Password Type='http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-username-token-profile-1.0#PasswordText'>{PASSWORD}</wsse:Password> 
            </wsse:UsernameToken> 
        </wsse:Security> 
        <wsa:MessageID>{MESSAGEID}</wsa:MessageID> 
        <wsa:To>{TO}</wsa:To> 
        <wsa:Action>{ACTION}</wsa:Action> 
        <wsa:From> 
            <wsa:Address>{ADDRESS}</wsa:Address> 
        </wsa:From> 
    </soapenv:Header>
    <soapenv:Body>
        {BODY}
    </soapenv:Body>
</soapenv:Envelope>");


var soapenv = settings.GetNamespaceOfPrefix("soapenv");
var wsa = settings.GetNamespaceOfPrefix("wsa");
var wsse = settings.GetNamespaceOfPrefix("wsse");
var wsu = settings.GetNamespaceOfPrefix("wsu");

XElement username = settings.Elements(soapenv + "Header").Elements(wsse + "Security").Elements(wsse + "UsernameToken").Elements(wsse + "Username").Single();
Console.WriteLine(username);
username.Value = "NewValue";
Console.WriteLine(username);

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