| Project | NuGet |
|---|---|
| XPath2 | |
| XPath2.Extensions |
Project is forked from https://xpath2.codeplex.com/
- .NET 3.5
- .NET 4.0 and up
- .NET Standard 2.0
This is an implementation of W3C XML Path Language (XPath) 2.0 for .NET Framework based on standard XPathNavigator API. The given implementation based on practice of developing XQuery is fully corresponding to the specification demands. This is single assembly 302K size.
It conforms for 12952 from 15133 (85.59%) regarding the test-set (XQTS 1.0.2 Nov. 20, 2006) at https://dev.w3.org/2006/xquery-test-suite/PublicPagesStagingArea/
API used is an anology to the standard one built into the platform: you utilize XPath2Expression instead of the common XPathExpression and a set of extension functions for XNode, XPathNavigator and XmlNode classes.
| System.Xml.XPath | WmHelp.XPath2 |
|---|---|
| XPathNavigator.Evaluate() | XPathNavigator.XPath2Evaluate() |
| XmlNode.SelectNodes() | XmlNode.XPath2SelectNodes() |
| XmlNode.SelectSingleNode() | XmlNode.XPath2SelectSingleNode() |
| XNode.Select() | XNode.XPath2Select() |
| ..., etc. | ..., etc. |
In addition there parameterized XPath2 expressions are implemented that allow to compose XQuery requests by standard Linq-to-XML means. Though it is not generally necessary to use XPath during writing Linq-to-XML queries nevertheless they allow to make it simple. To pass variable values into XPath expression we use C# 4.0 anonimous structures, e.g. new { varname = value, ... } creates variable $varname,... inside XPath expression.
Here're examples of some W3C XQuery usecases and their translations into C# and LINQ.
XQuery (RQ2.xq)
<result>
{
for $i in doc("items.xml")//item_tuple
let $b := doc("bids.xml")//bid_tuple[itemno = $i/itemno]
where contains($i/description, "Bicycle")
order by $i/itemno
return
<item_tuple>
{ $i/itemno }
{ $i/description }
<high_bid>{ max($b/bid) }</high_bid>
</item_tuple>
}
</result> C#
XNode items = XDocument.Load("items.xml");
XNode bids = XDocument.Load("bids.xml");
XNode result = new XDocument(
new XElement("result",
(from item in items.XPath2SelectElements("//item_tuple")
.OrderBy((elem) => (string)elem.Element("itemno"))
let bid = bids.XPath2Select<XElement>("//bid_tuple[itemno = $i/itemno]", new { i = item })
where ((string)item.Element("description")).Contains("Bicycle")
select new XElement("item_tuple",
item.Element("itemno"),
item.Element("description"),
!bid.Any() ? null :
new XElement("high_bid",
bid.AsQueryable().Max((elem) => (double)elem.Element("bid"))))))
);XQuery (RQ3.xq)
<result>
{
for $u in doc("users.xml")//user_tuple
for $i in doc("items.xml")//item_tuple
where $u/rating > "C"
and $i/reserve_price > 1000
and $i/offered_by = $u/userid
return
<warning>
{ $u/name }
{ $u/rating }
{ $i/description }
{ $i/reserve_price }
</warning>
}
</result>C#
XNode users = XDocument.Load("users.xml");
XNode items = XDocument.Load("items.xml");
XNode result =
new XElement("result",
(from user in users.XPath2SelectElements("//user_tuple")
from item in items.XPath2SelectElements("//item_tuple")
where (bool)XPath2Expression.Evaluate(@"$u/rating > 'C' and $i/reserve_price > 1000
and $i/offered_by = $u/userid", new { u = user, i = item })
select new XElement("warning",
user.Element("name"),
user.Element("rating"),
item.Element("description"),
item.Element("reserve_price"))));XQuery (RQ9.xq)
<result>
{
let $end_dates := doc("items.xml")//item_tuple/end_date
for $m in distinct-values(for $e in $end_dates
return month-from-date($e))
let $item := doc("items.xml")
//item_tuple[year-from-date(end_date) = 1999
and month-from-date(end_date) = $m]
order by $m
return
<monthly_result>
<month>{ $m }</month>
<item_count>{ count($item) }</item_count>
</monthly_result>
}
</result>C#
XNode items = XDocument.Load("items.xml");
var endDates = items.XPath2SelectElements("//item_tuple/end_date");
XNode result =
new XElement("result",
(from month in XPath2Expression.SelectValues(@"distinct-values(for $e in $end_dates
return month-from-date($e))", new { end_dates = endDates }).OrderBy((arg) => arg)
let item = items.XPath2SelectElements(@"//item_tuple[year-from-date(end_date) = 1999
and month-from-date(end_date) = $m]", new { m = month })
select new XElement("monthly_result",
new XElement("month", month),
new XElement("item_count", item.Count())
)));