I have an xml file that returns a set of elements that are unique by a attribute value. This presents a problem, as I can not select a node by its name:
<doc>
<float name="score">1.2873721</float>
<arr name="2_category">
<long>3021</long>
</arr>
<arr name="ATR_FamilyName">
<str>Some Cookbook </str>
</arr>
<arr name="ATR_IsFamily">
<str>0</str>
</arr>
<arr name="ATR_SellPrice">
<str>49.95</str>
</arr>
<arr name="ATR_VendorId">
<str>ABC</str>
</arr>
<arr name="ATR_VendorName">
<str>WROX</str>
</arr>
</doc>
I am using linq to populate a "Product" class. I am able to select the elements by position, however this becomes a problem if the node doesn't exist. Is there a way to select a node based on the value of its attribute? In the below example, can I get the arr node if the @name attribute = "ATR_FamilyName"? In xpath it would be:
doc/arr[@name = 'ATR_FamilyName']/str
here is my linq to xml query:
var query = from rt in results
where (String)rt.Descendants().ElementAt(5).Element("str").Value == "0"
select new Product.Product
{
FamilyName = (String)rt.Descendants().ElementAt(3).Value
// doc/arr[@name = 'ATR_FamilyName']/str - select Family Name is arr/@name 'ATR_FamilyName'
MorePropertiestoset....
};
The most important advantage of LINQ to XML is its integration with Language-Integrated Query (LINQ). This integration enables you to write queries on the in-memory XML document to retrieve collections of elements and attributes.
Attributes are part of XML elements. An element can have multiple unique attributes. Attribute gives more information about XML elements. To be more precise, they define properties of elements.
The XElement class is one of the fundamental classes in LINQ to XML. It represents an XML element. The following list shows what you can use this class for: Create elements. Change the content of the element.
Node. Everything in an XML document is a node. For example, the entire document is the document node, and every element is an element node. Root node. The topmost node of a tree.
Like AS-CII's answer, but without using a query expression (except for the outer one), and with the cast for XAttribute
, and selecting the str
element value inside an anonymous type:
select new Product.Product
{
FamilyName = rt.Descendants("arr")
.Where(x => (string) x.Attribute("name") == "ATR_FamilyName")
.Select(x => (string) x.Element("str"))
.FirstOrDefault(),
MorePropertiesToSet....
};
Note that the use of a cast for the result of the call to Attribute("name")
means that if there are any elements which don't have the attribute, the cast will result in a null reference (which isn't equal to the string literal). If you use the Value
property, you'll get an exception. Sometimes an exception may be better - if that indicates that the data is fundamentally broken and you want to find out about it rather than just not match the value.
(The same is true for the cast of the XElement
to string
.)
With LINQ you can easily select just the nodes that have a specified attribute, like this:
var query = from node in results.Descendants("arr") // I believe you could use results.Elements("arr") here
where node.Attribute("name").Value == "ATR_FamilyName"
select new Product
{
FamilyName = node.Element("str").Value
};
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