C# Parsing XML via LINQ to create custom object

Question

I know there are many questions on this very topic but none of the examples I've tried have worked for me.

I have an existing XML document that is constructed like so:

<root>
    <ElementA>
        <element1>sometext</element1>
        <element2>sometext</element2>
        <element3>sometext</element3>
    </ElementA>

    <ElementA>
        <element1>sometext</element1>
        <element2>sometext</element2>
        <element3>sometext</element3>
    </ElementA>

    <ElementB>
        <element1>sometext</element1>
        <element2>sometext</element2>
        <element3>sometext</element3>
        <element4>sometext</element4>
        <element5>sometext</element5>
    </ElementB>

    <ElementB>
        <element1>sometext</element1>
        <element2>sometext</element2>
        <element3>sometext</element3>
        <element4>sometext</element4>
        <element5>sometext</element5>
    </ElementB>

    <ElementC>
        <element1>sometext</element1>
        <element2>sometext</element3>
    </ElementC>

    <ElementC>
        <element1>sometext</element1>
        <element2>sometext</element2>
    </ElementC>
</root>

I need to find all the ElementA, B, and Cs and create a new object of type objA, etc. whose properties correspond to the respective element's child elements. Below is example code that I've tried.

var doc = XElement.Load(filename);
var data = from ele in doc.Elements()
           where ele.Name.LocalName.Equals("ElementA")
           select new objA
           {
                name = ele.Element("element1").Value
                address = ele.Element("element2").Value
           };

But this throws a null exception error when I try iterating through "data" collection. What am I not understanding?

MarcinJuraszek · Accepted Answer · 2013-03-24 14:25:38Z

1

You can get elements by its name using Elements("tagName"):

var data = from ele in doc.Elements("ElementA")
           select new objA
           {
               name = (string)ele.Element("element1"),
               address = (string)ele.Element("element2")
           };

You also should use (string)XElementInstance instead of XElementInstance.Value, to avoid NullReferenceException when element does not exist in XML.

Code pasted above returns 2 elements for your sample input data.

answered Mar 24, 2013 at 14:25

MarcinJuraszek

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8 Comments

Jake Shakesworth Over a year ago

Doesn't work for me. "data" ends up null. I had tried your solution previously but it seems like doc.Elements("ElementA") doesn't find ElementA. That's why I had to use the "where ele.Name.LocalName.Equals()"

MarcinJuraszek Over a year ago

So your real data has to be incorrect. I've tested it with your sample one and works fine.

Jake Shakesworth Over a year ago

True, I am wondering if there is something wonky with this XML doc. The example I gave is not the original data but represents the logical layout. Unfortunately this particular XML file I am forced to work with. I've successfully parsed if previously using foreach loops and switch/cases but it's very ugly.

MarcinJuraszek Over a year ago

The only think I have on my mind is a case, when your ElementA is not directly under root element. You should use Descendants instead of Elements when that is your case.

Fyodor Soikin Over a year ago

Does your real document have a namespace by any chance?

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