I have an XDocument object where I am trying to get the direct parent element based on a child element's value.
Getting the child element's value has been no issue, but I am struggling with finding the correct way to get only the parent element. Having not worked with XML much, I have a suspicion that the solution is simple and I am overthinking it.
Essentially, based on the below XML, if <Active>true</Active> then I want the direct parent element (i.e. <AlertNotification>) and no other elements.
Thank you in advance.
An example of the XML
<?xml version="1.0" encoding="utf-16"?>
<Policies xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLschema">
<PolicyID>1</PolicyID>
<EmailNotification>
<Active>false</Active>
</EmailNotification>
<AlertNotification>
<Active>true</Active>
</AlertNotification>
<AlarmEnabled>
<Active>false</Active>
</AlarmEnabled>
</Policies>
I thinks you should replace the utf-16 in the first line to utf-8. Then you may try this:
XDocument doc = XDocument.Load(your file);
var elements = doc.Descendants("Active")
.Where(i => i.Value == "true")
.Select(i => i.Parent);
Related
I have a little problem that I thought was a no-brainer ... but alas ...
I have some xml and all I want to do is to add the xml:space="preserve" to the root element using c#.
I tried this:
var rootElem = xDoc.Root; // XDocument
rootElem.SetAttributeValue("{xml}space", "preserve");
The result of this is:
<ProjectDetails xmlns="http://site/ppm" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" p3:space="preserve" xmlns:p3="xml">
I think this is equivalent to
<ProjectDetails xmlns="http://site/ppm" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xml:space="preserve">
But since xml:space is a special attribute, I am a bit in doubt.
So:
Are they identical?
Is there a way I can add this to the document in a "clean" way?
You just need the right XName value - I'd use this:
doc.Root.SetAttributeValue(XNamespace.Xml + "space", "preserve");
The XName +(XNamespace, string) operator is generally the simplest way to work with namespaces in LINQ to XML, in my experience.
I have a UI that uses the DataGridView to display the content of XML files.
If XmlNode contains only InnerText, it's quite simple, however I'm having a problem with nodes that contains childnodes (and not only string).
Simple
<node>value</node>
Displayed as "value" in DataGridViewCell.
Complex
<node>
<foo>bar</foo>
<foo2>bar</foo2>
</node>
The problem is that the InnerXml code is not intended and it's very hard to modify in UI.
I've tried to use XmlTextWriter to "beautify" the string - it works quite well, however requires a XmlNode (includes node, not only childnodes) and I cannot assign it back to InnerXml.
I would like to either see following in the UI:
<foo>bar</foo>
<foo2>bar</foo2>
(this can be assigned to InnerXml afterwards)
Or
<node>
<foo>bar</foo>
<foo2>bar</foo2>
</node>
(and find a way how to replace OuterXml with this string).
Thanks for any ideas,
Martin
You can load the OuterXml to XElement, then use String.Join() to join all child elements of the root node (in other point-of-view, the InnerXml) separated by line break, for example :
XElement e = e.Parse(something.OuterXml);
var result = string.Join(
Environment.NewLine,
e.Elements().Select(o => o.ToString())
);
I am trying to compose an algorithm that will take XML as input, and find a value associated with a particular element, but the position of the element within the XML body varies. I have seen many examples of using XDocument.Descendants() but most (if not all) the examples expect the structure to be consistent, and descendants well known. I presume I will need to recurse the XML to find this value, but before heading that way, ask the general population.
What is the best way to find an element in an XDocument when the path for the element may be different on each call? Just need the first occurrence found, not in any particular order. Can be first occurrence found by going wide, or by going deep.
For example, if I am trying to find the element "FirstName", and if the input XML for Call one looks like..
<?xml version="1.0"?>
<PERSON><Name><FirstName>BOB</FirstName></Name></PERSON>
and the next call looks like:
<?xml version="1.0"?>
<PERSONS><PERSON><Name><FirstName>BOB</FirstName></Name></PERSON></PERSONS>
What do you recommend? Is there a "Find" option in XDocument that I have not seen?
UPDATE:
Simple example above works with lazyberezovsky answer of XDocument.Descendents, but real XML does not. My problematic XML...
<s:Envelope xmlns:s="http://schemas.xmlsoap.org/soap/envelope/">
<s:Header>
<To s:mustUnderstand="1" xmlns="http://schemas.microsoft.com/ws/2005/05/addressing/none">http://localhost:52087/Service1.svc</To>
<Action s:mustUnderstand="1" xmlns="http://schemas.microsoft.com/ws/2005/05/addressing/none">http://tempuri.org/IService1/GetDataUsingDataContract</Action>
</s:Header>
<s:Body>
<GetDataUsingDataContract xmlns="http://tempuri.org/">
<composite xmlns:a="http://schemas.datacontract.org/2004/07/WcfService2" xmlns:i="http://www.w3.org/2001/XMLSchema-instance">
<a:BoolValue>false</a:BoolValue>
<a:Name>
<a:FirstName>BOB</a:FirstName>
</a:Name>
<a:StringValue i:nil="true" />
</composite>
</GetDataUsingDataContract>
</s:Body>
</s:Envelope>
UPDATE:
lazyberezovsky helped immensely showing me how Descendents is supposed to work. Be careful of namespaces in XML. Lesson learned. Found another . article with similar issues..
Search XDocument using LINQ without knowing the namespace
Resolved using the following snippet...
var xdoc = XDocument.Parse(xml);
var name = (from p in xdoc.Descendants() where p.Name.LocalName == "FirstName" select p.Value).FirstOrDefault();
When you are using Descendants for finding first occurrence of element, you don't need to know
structure of file. Following code will work for both your cases:
var xdoc = XDocument.Load(path_to_xml);
var name = (string)xdoc.Descendants("FirstName").FirstOrDefault();
Same with XPath
var name = (string)xdoc.XPathSelectElement("//FirstName[1]");
Without knowing all the possible permutations of the XML document (which is very unusual by the way) I don't think anyone could hope to give you any worthwhile recommendations.
"Just need the first occurrence found, not in any particular order." I think Descendants do trick. Look at this:
string xml = #"<?xml version=""1.0""?>
<PERSONS>
<PERSON>
<Name>
<FirstName>BOB</FirstName>
</Name>
</PERSON>
</PERSONS>";
XDocument doc = XDocument.Parse(xml);
Console.WriteLine(string.Join(",", doc.Descendants("FirstName").Select(e =>(string)e)));
xml = #"<?xml version=""1.0""?>
<PERSON>
<Name>
<FirstName>BOB</FirstName>
</Name>
</PERSON>";
doc = XDocument.Parse(xml);
Console.WriteLine(string.Join(",", doc.Descendants("FirstName").Select(e =>(string)e)));
I am looking for a good approach that can remove empty tags from XML efficiently. What do you recommend? Regex? XDocument? XmlTextReader?
For example,
const string original =
#"<?xml version=""1.0"" encoding=""utf-16""?>
<pet>
<cat>Tom</cat>
<pig />
<dog>Puppy</dog>
<snake></snake>
<elephant>
<africanElephant></africanElephant>
<asianElephant>Biggy</asianElephant>
</elephant>
<tiger>
<tigerWoods></tigerWoods>
<americanTiger></americanTiger>
</tiger>
</pet>";
Could become:
const string expected =
#"<?xml version=""1.0"" encoding=""utf-16""?>
<pet>
<cat>Tom</cat>
<dog>Puppy</dog>
<elephant>
<asianElephant>Biggy</asianElephant>
</elephant>
</pet>";
Loading your original into an XDocument and using the following code gives your desired output:
var document = XDocument.Parse(original);
document.Descendants()
.Where(e => e.IsEmpty || String.IsNullOrWhiteSpace(e.Value))
.Remove();
This is meant to be an improvement on the accepted answer to handle attributes:
XDocument xd = XDocument.Parse(original);
xd.Descendants()
.Where(e => (e.Attributes().All(a => a.IsNamespaceDeclaration || string.IsNullOrWhiteSpace(a.Value))
&& string.IsNullOrWhiteSpace(e.Value)
&& e.Descendants().SelectMany(c => c.Attributes()).All(ca => ca.IsNamespaceDeclaration || string.IsNullOrWhiteSpace(ca.Value))))
.Remove();
The idea here is to check that all attributes on an element are also empty before removing it. There is also the case that empty descendants can have non-empty attributes. I inserted a third condition to check that the element has all empty attributes among its descendants. Considering the following document with node8 added:
<root>
<node />
<node2 blah='' adf='2'></node2>
<node3>
<child />
</node3>
<node4></node4>
<node5><![CDATA[asdfasdf]]></node5>
<node6 xmlns='urn://blah' d='a'/>
<node7 xmlns='urn://blah2' />
<node8>
<child2 d='a' />
</node8>
</root>
This would become:
<root>
<node2 blah="" adf="2"></node2>
<node5><![CDATA[asdfasdf]]></node5>
<node6 xmlns="urn://blah" d="a" />
<node8>
<child2 d='a' />
</node8>
</root>
The original and improved answer to this question would lose the node2 and node6 and node8 nodes. Checking for e.IsEmpty would work if you only want to strip out nodes like <node />, but it's redunant if you're going for both <node /> and <node></node>. If you also need to remove empty attributes, you could do this:
xd.Descendants().Attributes().Where(a => string.IsNullOrWhiteSpace(a.Value)).Remove();
xd.Descendants()
.Where(e => (e.Attributes().All(a => a.IsNamespaceDeclaration))
&& string.IsNullOrWhiteSpace(e.Value))
.Remove();
which would give you:
<root>
<node2 adf="2"></node2>
<node5><![CDATA[asdfasdf]]></node5>
<node6 xmlns="urn://blah" d="a" />
</root>
As always, it depends on your requirements.
Do you know how the empty tag will display? (e.g. <pig />, <pig></pig>, etc.) I usually do not recommend using Regular Expressions (they are really useful but at the same time they are evil). Also considering a string.Replace approach seems to be problematic unless your XML doesn't have a certain structure.
Finally, I would recommend using an XML parser approach (make sure your code is valid XML).
var doc = XDocument.Parse(original);
var emptyElements = from descendant in doc.Descendants()
where descendant.IsEmpty || string.IsNullOrWhiteSpace(descendant.Value)
select descendant;
emptyElements.Remove();
Anything you use will have to pass through the file once at least. If its just a single named tag that you know then regex is your friend otherwise use a stack approach. Start with parent tag and if it has a sub tag place it in stack. If you find an empty tag remove it then once you have gone through child tags and reached the ending tag of what you have on top of stack then pop it and check it as well. If its empty remove it as well. This way you can remove all empty tags including tags with empty children.
If you are after a reg ex expression use this
XDocument is probably simplest to implement, and will give adequate performance if you know your documents are reasonably small.
XmlTextReader will be faster and use less memory than XDocument when processing very large documents.
Regex is best for handling text rather than XML. It might not handle all edge cases as you would like (e.g. a tag within a CDATA section; a tag with an xmlns attribute), so is probably not a good idea for a general implementation, but may be adequate depending on how much control you have of the input XML.
XmlTextReader is preferable if we are talking about performance (it provides fast, forward-only access to XML). You can determine if tag is empty using XmlReader.IsEmptyElement property.
XDocument approach which produces desired output:
public static bool IsEmpty(XElement n)
{
return n.IsEmpty
|| (string.IsNullOrEmpty(n.Value)
&& (!n.HasElements || n.Elements().All(IsEmpty)));
}
var doc = XDocument.Parse(original);
var emptyNodes = doc.Descendants().Where(IsEmpty);
foreach (var emptyNode in emptyNodes.ToArray())
{
emptyNode.Remove();
}
If I get the path to a specific node as a string can I somehow easily find said node by using Linq/Method of the XElement ( or XDocument ).
There are so many different types of XML objects it would also be nice if as a added bonus you could point me to a guide on why/how to use different types.
EDIT: Ok after being pointed towards XPathSelectElement I'm trying it out so I can give him the right answer I can't quite get it to work though. This is the XML I'm trying out
<Product>
<Name>SomeName</Name>
<Type>SomeType</Type>
<Quantity>Alot</Quantity>
</Product>
and my code
string path = "Product/Name";
string name = xml.XPathSelectElement(path).Value;
note my string is coming from elsewhere so I guess it doesn't have to be literal ( at least in debug mode it looks like the one above). I've also tried adding / in front. It gives me a null ref.
Try using the XPathSelectElement extension method of XElement. You can pass the method an XPath expression to evaluate. For example:
XElement myElement = rootElement.XPathSelectElement("//Book[#ISBN='22542']");
Edit:
In reply to your edit, check your XPath expression. If your document only contains that small snippet then /Product/Name will work as the leading slash performs a search from the root of the document:
XElement element = document.XPathSelectElement("/Product/Name");
If there are other products and <Product> is not the root node you'll need to modify the XPath you're using.
You can also use XPathEvaluate
XDocument document = XDocument.Load("temp.xml");
var found = document.XPathEvaluate("/documents/items/item") as IEnumerable<object>;
foreach (var obj in found)
{
Console.Out.WriteLine(obj);
}
Given the following xml:
<?xml version="1.0" encoding="utf-8" ?>
<documents>
<items>
<item name="Jamie"></item>
<item name="John"></item>
</items>
</documents>
This should print the contents from the items node.