I have the following xml file
<root xmlns="http://mynamespace">
<parent>
<first>text</first>
<second>more</second>
</parent>
<parent>
<first>2</first>
<second>3</second>
</parent>
<parent>
<first>aa</first>
<second>bb</second>
</parent>
</root>
I'm trying to get first and second children of parent.
C# seems to have problems with the following code (the error is on the last line):
var rawXml = #"<root xmlns=""http://mynamespace"">
<parent>
<first>text</first>
<second>more</second>
<third>hello</third>
</parent>
<parent>
<first>2</first>
<second>3</second>
<parent>
<first>a</first>
<second>b</second>
</parent>
</parent>
<parent>
<first>aa</first>
<second>bb</second>
</parent>
</root>";
var xmlDoc = new XmlDocument();
xmlDoc.LoadXml(rawXml);
var ns = new XmlNamespaceManager(xmlDoc.NameTable);
ns.AddNamespace("m", "http://mynamespace");
var nav = xmlDoc.CreateNavigator();
var parents = nav.Select("//m:parent", ns);
Console.Write($"Got {parents.Count} parents.");
// this does not work
// error: Expression must evaluate to a node-set.
//var siblings = nav.Select("//m:parent/(m:first|m:second)", ns);
// but this does
var siblings = nav.Select("//m:parent/m:first|//m:parent/m:second", ns);
Console.Write($"Got {siblings.Count} children.");
Am I missing something? Is the first XPath expression wrong?
Is the first XPath expression wrong?
Yes, it's not valid XPath 1.0 syntax. You can't have a ( after a / in XPath 1.0.
You can achieve what you're trying to do, without repeating any node names, by using this path:
/m:root/m:parent/*[self::m:first or self::m:second]
Side note: avoid using // unless you have a specific reason to use it. It's bad for performance.
Related
I am writing a C# function where I need to fetch the value of a node using Xpath and if the fetched values matches a given string, I need to pass the Xpath to an API which replaces the current value of the node with value stored in Database.
The problem is there are multiple matches for the given Xpath, I filter those out with the string matching criteria and am able to figure out the node, however, I am not getting how to capture the exact Xpath of matching node and pass it to the API for it to work.
Lets take this XML as an example
<GrandParent>
<Parent>
<Child1>John
</Child1>
<Child2>Emily
</Child2>
</Parent>
<Parent>
<Child1>Frank
</Child1>
<Child2>Niki
</Child2>
</Parent>
<Parent>
<Child1>Mia
</Child1>
<Child2>Noah
</Child2>
</Parent>
</GrandParent>
Now I will have to fetch the node with Xpath /GrandParent/Parent/Child1 whose value would be John.
I am doing that in C# using XPathNavigator and XPathIterator
XmlDocument xmlDoc = new XmlDocument();
xmlDoc.LoadXml(requestXML);
XPathNavigator nav;
nav = xmlDoc.CreateNavigator();
XPathNodeIterator allMatchingNodes = nav.Select(SourceXPath);
int countNodes = 1;
foreach (XPathNavigator node in allMatchingNodes)
{
if(node.Value.Equals("John"))
{
Xpath = SourceXPath + "[" + countNodes + "]";
break;
}
}
However, this would be an incorrect approach as it will create xpath as /GrandParent/Parent/Child1[1] and hence the subsequeent API replaces is incorrectly.
I would want xpath as /GrandParent/Parent[1]/Child1 is there someway of doing that without using multiple foreach?
I'm trying to get all elements with a given value, "John", from an xml document.
Is this possible with LINQ to XML?
What I want to achieve is to replace all "John" values with "Wayne". I know this can easily be done with xslt, but I need to do this by code.
My XML:
<Root>
<Parents>
<Parent>
<Name>John</Name>
<Age>18</Age>
</Parent>
<Parent>
<Name>John</Name>
<Age>25</Age>
</Parent>
<Parent>
<Name>Peter</Name>
<Age>31</Age>
</Parent>
</Parents>
</Root>
I have tried this:
XmlDocument doc = new XmlDocument();
doc.Load(#"C:/Temp/test.xml");
var elements = doc.Elements().Where(w => w.Value == "John");
foreach (var element in elements)
{
element.Value = "Wayne";
}
You may use System.Xml.Linq.XDocument. It's more easy to work with.
XDocument doc = XDocument.Load(your file path);
var elements = doc.Descendants("Name").Where(i => i.Value == "John");
foreach (var element in elements)
{
element.Value = "Wayne";
}
doc.Save(your save file path);
Here is the output:
<?xml version="1.0" encoding="utf-8"?>
<Root>
<Parents>
<Parent>
<Name>Wayne</Name>
<Age>18</Age>
</Parent>
<Parent>
<Name>Wayne</Name>
<Age>25</Age>
</Parent>
<Parent>
<Name>Peter</Name>
<Age>31</Age>
</Parent>
</Parents>
</Root>
Here is an approach that will get all elements with the value John, regardless of what element (although only at the same level; you'd have to modify it to look at different levels too; you could use the Descendants approach described previously):
XDocument doc = XDocument.Load(#"C:\temp\test.xml");
var ns = doc.Root.GetDefaultNamespace();
var elements = doc.Element(ns + "Root").Element(ns + "Parents").Elements(ns + "Parent").Elements().Where(w => w.Value == "John");
foreach (var element in elements)
{
element.Value = "Wayne";
}
var stream = new FileStream(#"C:\temp\test.xml", FileMode.Create);
doc.Save(stream);
I have strings of xpath like
/root/parent/child
/root/parent/child[1]
/root/parent/child[2]
In the c# code i am checking if the xpath exist in XmlDocument and cloning it like this
//Get the parent node of the node to be cloned
XmlNode NodeTobeCloned = xmlDoc.SelectSingleNode(oRow[0].ToString());
XmlNode DuplicateNode = NodeTobeCloned.CloneNode(true);
DuplicateNode.InnerText = sValue;
//Insert the node after the last child of a commoon parent
NodeTobeCloned.ParentNode.AppendChild(DuplicateNode);
I am getting a result like
<root>
<parent>
<child/>
<child/>
<child/>
</parent>
</root>
I want a result like
<root>
<parent>
<child/>
</parent>
<parent>
<child/> -- [1] -predicates elements
</parent>
<parent>
<child/> -- [2] -predicates elements
</parent>
</root>
how can i append to xmldocument using c#
thank you
I currently have an XML Structure that looks something like this
<Parent>
<Info>
<Info-Data></Info-Data>
<Info-Data2></Info-Data2>
</Info>
<Message>
<Foo></Foo>
<Bar></Bar>
</Message>
<Message>
<Foo/>
<Bar/>
</Message>
</Parent>
What I'm trying to accomplish is split each Message into it's own unique XDocument. I want it to be
<Parent>
<Info />
<Message />
</Parent>
I tried to do the following.
XDocument xDoc = XDocument.Parse(myXMLString);
IEnumerable<XElement> elements = xDoc.Descendants(xDoc.Root.Name.NameSpace + "Message");
foreach(XElement element in elements)
{
XDocument newDoc = XDocument.Parse(element.ToString());
}
Obviously this only gets me everything from Message and below. I tried using Ancestors and AncestorsAndSelf but they always include BOTH Messages. Is there a different call I should be making?
If your format is fixed like this, it's not so bad:
foreach(XElement element in elements)
{
XDocument newDoc = new XDocument
(new XElement(xDoc.Root.Name,
xDoc.Root.Element("Info"),
element));
// ...
}
It's not great, but it's not horrendous. An alternative is to clone the original document, remove all the Message elements, then repeatedly clone the "gutted" version and add one element at a time to the new clone:
XDocument gutted = new XDocument(xDoc);
gutted.Descendants(xDoc.Root.Name.Namespace + "Message").Remove();
foreach(XElement element in elements)
{
XDocument newDoc = new XDocument(gutted);
newDoc.Root.Add(element);
// ...
}
I have set of XML's ( varies between 2 and 6) that needs to be processed(traversed and checked for certain data and relations within) - The XML's have some "Recursive Data"
here is a simple example involving a test data for explanation - 2 files considered as example
File1.xml:
<some root------standard header not entered for the example----->
<parent>
<ID>AB-1234</ID>
<Description>Good book</Description>
<Date_Created>08-10-2011</Date_Created>
<child>
<ID>BC-0001</ID>
<Description>Nice</Description>
</child>
</parent>
<parent>
<ID>BC-0001</ID>
<Description>Work Together</Description>
<Date_Created>08-10-2011</Date_Created>
<child>
<ID>DC-0011</ID>
<Description>Happy</Description>
</child>
</parent>
File2.xml:
<some root------standard header not entered for the example----->
<parent>
<ID>DC-0011</ID>
<Description> book</Description>
<Date_Created>08-10-2011</Date_Created>
<child>
<ID>EF-0001</ID>
<Description>Nice</Description>
</child>
</parent>
<parent>
<ID>EF-0001</ID>
<Description>Work Together</Description>
<Date_Created>08-10-2011</Date_Created>
<child>
<ID>PQ-0011</ID>
<Description>Happy</Description>
</child>
</parent>
code I am using involves 1) loading both the XML files and combining them
XDocument test1doc = XDocument.Load(#"d:\File1.xml");
XDocument test2doc = XDocument.Load(#"d:\File2.xml");
IEnumerable<XElement> testElist1 = test1doc.decendants("parent");
IEnumerable<XElement> testElist2 = test2doc.decendants("parent");
IEnumerable<XElement> testElistcombo = testElist1.union(testElist2);
2) use the testElistcombo to navigate the elements using foreach - 2 foreach loops (one for the parent and second for the child)
3) while traversing use an if condition to check whether parent ID and Child ID are equal.
I am able to build the hierarchy - no problem with that.
I was able to print the hierarchy along with the level value of the hierarchy.by including a counter in each of the foreach loops.
my output looks like
AB-1234[level-0]
>>BC-0001[level-1]
>>DC-0011[level-3]
..... and so on.
as i said no problem with that. -
Following is the area where i would like some help:
1) when the number of files increases to more than 2 to a max 6, i am using a union in the following manner
XDocument test1doc = XDocument.Load(#"d:\File1.xml");
XDocument test2doc = XDocument.Load(#"d:\File2.xml");
XDocument test3doc = XDocument.Load(#"d:\File3.xml");
XDocument test4doc = XDocument.Load(#"d:\File4.xml");
XDocument test5doc = XDocument.Load(#"d:\File5.xml");
XDocument test6doc = XDocument.Load(#"d:\File6.xml");
IEnumerable<XElement> testElist1 = test1doc.decendants("parent");
IEnumerable<XElement> testElist2 = test2doc.decendants("parent");
IEnumerable<XElement> testElist3 = test3doc.decendants("parent");
IEnumerable<XElement> testElist4 = test4doc.decendants("parent");
IEnumerable<XElement> testElist5 = test5doc.decendants("parent");
IEnumerable<XElement> testElist6 = test6doc.decendants("parent");
IEnumerable<XElement> testElistcombo1 = testElist1.union(testElist2);
IEnumerable<XElement> testElistcombo2 = testElistcombo1.union(testElist3);
IEnumerable<XElement> testElistcombo3 = testElistcombo2.union(testElist4);
IEnumerable<XElement> testElistcombo4 = testElistcombo3.union(testElist5);
IEnumerable<XElement> testElistcombo5 = testElistcombo4.union(testElist6);
and use the testElistcombo5.for processing.
help required: an alternative way to load and combine the XML's to for processing.
2) The process is resource intensive and take a fair bit of time to complete the hierarchy building
help required: is there an alternative way to process the xml's for building hierarchy in Recursive Data.
Question 1: you can do this using the Enumerable.Aggregate function to aggregate the elements for each document into one set of elements:
IEnumerable<string> filenames = { "filename1.xml", "filename2.xml" };
IEnumerable<XDocument> documents = filenames.Select(XDocument.Load);
IEnumerable<IEnumerable<XElement>> documentsElements = documents.Select(document => document.Descendants("parent"));
IEnumerable<XElement> elements = documentsElements.Aggregate((working, next) => working.Union(next));