I am looking for a linq to Xdoc query to group by a subset of the XML nodes. I've only been able to get this working to return a subset of the data but I need the entire xml document passed back with only the particular nodes grouped.
<Root>
<Elementname1>
</Elementname1>
<Elementname2>
</Elementname2>
<Elementname3 attrname="test1">
<Child>
</Child>
</Elementname3>
<Elementname3 attrname="test1">
<Child>
</Child>
</Elementname3>
</Root>
This code:
var result =
from row in xDoc.Descendants("Elementname3")
group row by (string)row.Attribute("attrname") into g
select g.First();
returns:
<Elementname3 attrname="test1">
<Child></Child>
</Elementname3>
Expecting:
<Root>
<Elementname1>
</Elementname1>
<Elementname2>
</Elementname2>
<Elementname3 attrname="test1">
<Child>
</Child>
</Elementname3>
</Root>
I understand since descendant element is starting at elementname3; just not sure on how to expound the linq query to start with the root node and group as expected.
Try this:
var result = new XDocument(
new XElement("Root",
from x in doc.Root.Elements()
group x by new { x.Name, Attr = (string)x.Attribute("attrname") } into g
select g.First()
)
);
Related
This is my XML..
<rootparent>
<root>
...other nodes here.
...
<parent>
<child id="child_1">
.some other nodes ..
</child>
<child id="child_2">
.some other nodes ..
</child>
...other nodes
</parent>
</root>
</rootparent>
I need to select all the child nodes where id like 'child_%' using LINQ to XML.
I got the xpath for this
string xPath="/root/parent/child[id='child_*']";
var x1 =xml.XPathSelectElement(xPath);
var x2 = _sourceDoc.Root.XPathEvaluate(xPath);
but it returns Enumeration yielded no results.
Using xml linq :
string xml =
"<rootparent>" +
"<root>" +
"<parent>" +
"<child id=\"child_1\">" +
"</child>" +
"<child id=\"child_2\">" +
"</child>" +
"</parent" +
"</root>" +
"</rootparent>";
XDocument doc = XDocument.Parse(xml);
List<XElement> children = doc.Descendants("child")
.Where(x => ((string)x.Attribute("id")).StartsWith("child_"))
.ToList();
For starters, your xpath doesn't match the structure of your XML. Your query assumes the root is called root but there's a rootparent and you don't account for it. Since you're just looking for child nodes, you don't even need to reference it, just go through the descendants.
You need to use the appropriate condition. None of your children contains an id element named child_* so naturally you won't get any results. Use the starts-with function and access the id attribute.
//child[starts-with(#id, 'child_')]
I have 2 XML elements(from different XML documents with the same schema) of the same type looking like this:
<Parent>
<ChildType1>contentA</ChildType1>
<ChildType2>contentB</ChildType2>
<ChildType3>contentC</ChildType3>
</Parent>
<Parent>
<ChildType1>contentD</ChildType1>
<ChildType3>contentE</ChildType3>
</Parent>
Element types ChildType1, ChildType2 and ChildType3 can have at most one instance in the Parent element.
What I need to do is merge the content of the second Parent node with the first Parent node into a new node that would look like this:
<Parent>
<ChildType1>contentD</ChildType1>
<ChildType2>contentB</ChildType2>
<ChildType3>contentE</ChildType3>
</Parent>
Use Linq to XML to parse the source documents. Then create a union between them and group by element name and create a new document using the first/last elements in the groups depending on what you want.
Something like this:
var doc = XElement.Parse(#"
<Parent>
<ChildType1>contentA</ChildType1>
<ChildType2>contentB</ChildType2>
<ChildType3>contentC</ChildType3>
</Parent>
");
var doc2 = XElement.Parse(#"
<Parent>
<ChildType1>contentD</ChildType1>
<ChildType3>contentE</ChildType3>
</Parent>
");
var result =
from e in doc.Elements().Union(doc2.Elements())
group e by e.Name into g
select g.Last();
var merged = new XDocument(
new XElement("root", result)
);
merged now contains
<root>
<ChildType1>contentD</ChildType1>
<ChildType2>contentB</ChildType2>
<ChildType3>contentE</ChildType3>
</root>
If you name the two initial documents as xd0 and xd1 then this worked for me:
var nodes =
from xe0 in xd0.Root.Elements()
join xe1 in xd1.Root.Elements() on xe0.Name equals xe1.Name
select new { xe0, xe1, };
foreach (var node in nodes)
{
node.xe0.Value = node.xe1.Value;
}
I got this result:
<Parent>
<ChildType1>contentD</ChildType1>
<ChildType2>contentB</ChildType2>
<ChildType3>contentE</ChildType3>
</Parent>
I have the following XML and query through the ID,how do get the Parent Hierarchy
<Child>
<Child1 Id="1">
<Child2 Id="2">
<Child3 Id="3">
<Child4 Id="4">
<Child5 Id="5"/>
<Child6 Id="6"/>
</Child4>
</Child3>
</Child2>
</Child1>
</Child>
In this if i query(Id = 4) and find out the Parent elements using Linq in the particular element how to get the following output with Hierarchy.
<Child>
<Child1 Id="1">
<Child2 Id="2">
<Child3 Id="3">
<Child4 Id="4"/>
</Child3>
</Child2>
</Child1>
</Child>
Thanks In Advance.
Assume you want just one node parent tree:
string xml = #"<Child>
<Child1 Id="1">
<Child2 Id="2">
<Child3 Id="3">
<Child4 Id="4">
<Child5 Id="5"/>
<Child6 Id="6"/>
</Child4>
</Child3>
</Child2>
</Child1>
</Child>";
TextReader tr = new StringReader(xml);
XDocument doc = XDocument.Load(tr);
IEnumerable<XElement> myList =
from el in doc.Descendants()
where (string)el.Attribute("Id") == "4" // here whatever you want
select el;
// select your hero element in some way
XElement hero = myList.FirstOrDefault();
foreach (XElement ancestor in hero.Ancestors())
{
Console.WriteLine(ancestor.Name); // rebuild your tree in a separate document, I print ;)
}
To search for every element of your tree iterate retrieve the node with the select query without the where clause and call the foreach for every element.
Based on the sample XML provided, you could walk up the tree to find the parent node once you've found the node in question:
string xml =
#"<Child>
<Child1 Id='1'>
<Child2 Id='2'>
<Child3 Id='3'>
<Child4 Id='4'>
<Child5 Id='5'/>
<Child6 Id='6'/>
</Child4>
</Child3>
</Child2>
</Child1>
</Child>";
var doc = XDocument.Parse( xml );
// assumes there will always be an Id attribute for each node
// and there will be an Id with a value of 4
// otherwise an exception will be thrown.
XElement el = doc.Root.Descendants().First( x => x.Attribute( "Id" ).Value == "4" );
// discared all child nodes
el.RemoveNodes();
// walk up the tree to find the parent; when the
// parent is null, then the current node is the
// top most parent.
while( true )
{
if( el.Parent == null )
{
break;
}
el = el.Parent;
}
In Linq to XML there is a method called AncestorsAndSelf on XElement that
Returns a collection of elements that contain this element, and the
ancestors of this element.
But it will not transform your XML tree the way you want it.
What you want is:
For a given element, find the parent
Remove all elements from parent but the given element
Remove all elements from the given element
Something like this in Linq (no error handling):
XDocument doc = XDocument.Parse("<xml content>");
//finding element having 4 as ID for example
XElement el = doc.Descendants().First(el => el.Attribute("Id").Value == "4");
el.RemoveNodes();
XElement parent = el.Parent;
parent.RemoveNodes();
parent.Add(el);
[Edit]
doc.ToString() must give you what you want as a string.
[Edit]
Using RemoveNodes instead of RemoveAll, the last one also removes attributes.
Removing nodes from the chosen element too.
I found the following way
XElement elementNode = element.Descendants()
.FirstOrDefault(id => id.Attribute("id").Value == "4");
elementNode.RemoveNodes();
while (elementNode.Parent != null)
{
XElement lastNode = new XElement(elementNode);
elementNode = elementNode.Parent;
elementNode.RemoveNodes();
elementNode.DescendantsAndSelf().Last().AddFirst(lastNode);
}
return or Print elementNode.
I have an xml doc similar to this:
<Root>
<MainItem ID="1">
<SubItem></SubItem>
<SubItem></SubItem>
<SubItem></SubItem>
</MainItem>
<MainItem ID="2">
<SubItem></SubItem>
<SubItem></SubItem>
<SubItem></SubItem>
</MainItem>
...
</Root>
I want to return the whole of the MainItem element based on the value of attribute ID.
So effectively if Attribute ID is equal to 2, then give me that MainItem element back.
I can't work out how to do this with LINQ.
There seems to be a load of information on google, but I just can't quite seem to find what I'm looking for.
Little help ?
TIA
:-)
It could be something like this:
XDocument doc = XDocument.Load("myxmlfile.xml");
XElement mainElement = doc.Element("Root")
.Elements("MainItem")
.First(e => (int)e.Attribute("ID") == 2);
// additional work
How about this:
// load your XML
XDocument doc = XDocument.Load(#"D:\linq.xml");
// find element which has a ID=2 value
XElement mainItem = doc.Descendants("MainItem")
.Where(mi => mi.Attribute("ID").Value == "2")
.FirstOrDefault();
if(mainItem != null)
{
// do whatever you need to do
}
Marc
I changed your XML slightly to have values:
<?xml version="1.0"?>
<Root>
<MainItem ID="1">
<SubItem>value 1</SubItem>
<SubItem>val 2</SubItem>
<SubItem></SubItem>
</MainItem>
<MainItem ID="2">
<SubItem></SubItem>
<SubItem></SubItem>
<SubItem></SubItem>
</MainItem>
</Root>
And with this LINQ:
XDocument xmlDoc = XDocument.Load(#"C:\test.xml");
var result = from mainitem in xmlDoc.Descendants("MainItem")
where mainitem.Attribute("ID").Value == "1"
select mainitem;
foreach (var subitem in result.First().Descendants())
{
Console.WriteLine(subitem.Value);
}
Console.Read();
From here: How to: Filter on an Attribute (XPath-LINQ to XML)
// LINQ to XML query
IEnumerable<XElement> list1 =
from el in items.Descendants("MainItem")
where (string)el.Attribute("ID") == "2"
select el;
// XPath expression
IEnumerable<XElement> list2 = items.XPathSelectElements(".//MainItem[#ID='2']");
How to Get an XML Element from XDocument using LINQ ?
Suppose I have an XDocument Named XMLDoc which is shown below:
<Contacts>
<Node>
<ID>123</ID>
<Name>ABC</Name>
</Node>
<Node>
<ID>124</ID>
<Name>DEF</Name>
</Node>
</Contacts>
XElement Contacts = from xml2 in XMLDoc.Elements("Contacts").Elements("Node")
where xml2.Element("ID").Value == variable
select xml2;
But I am getting Error "Object Reference is NOT to set....."
How to get a particular Node from a XML file using LINQ?
I want to update some values in that node.
How can this be done?
test.xml:
<?xml version="1.0" encoding="utf-8"?>
<Contacts>
<Node>
<ID>123</ID>
<Name>ABC</Name>
</Node>
<Node>
<ID>124</ID>
<Name>DEF</Name>
</Node>
</Contacts>
Select a single node:
XDocument XMLDoc = XDocument.Load("test.xml");
string id = "123"; // id to be selected
XElement Contact = (from xml2 in XMLDoc.Descendants("Node")
where xml2.Element("ID").Value == id
select xml2).FirstOrDefault();
Console.WriteLine(Contact.ToString());
Delete a single node:
XDocument XMLDoc = XDocument.Load("test.xml");
string id = "123";
var Contact = (from xml2 in XMLDoc.Descendants("Node")
where xml2.Element("ID").Value == id
select xml2).FirstOrDefault();
Contact.Remove();
XMLDoc.Save("test.xml");
Add new node:
XDocument XMLDoc = XDocument.Load("test.xml");
XElement newNode = new XElement("Node",
new XElement("ID", "500"),
new XElement("Name", "Whatever")
);
XMLDoc.Element("Contacts").Add(newNode);
XMLDoc.Save("test.xml");
The .Elements operation returns a LIST of XElements - but what you really want is a SINGLE element. Add this:
XElement Contacts = (from xml2 in XMLDoc.Elements("Contacts").Elements("Node")
where xml2.Element("ID").Value == variable
select xml2).FirstOrDefault();
This way, you tell LINQ to give you the first (or NULL, if none are there) from that LIST of XElements you're selecting.
Marc