Linq query to select all the nodes based on an attribute value

Question

<Category id=1>
<MyLines>
      <Line GroupID="0" Cache="15" />
  <Rect GroupID="0" Cache="16"/>
  <Ellipse GroupID="0" Cache="16"/>
</MyLines>

My XML document contains many Category tags. Could you please let me know what is the best way to get each of the sub elements of MyLines whose Cache = 16 and remove them.

I am looking to achieve this using linq.

I was trying as below:

       var q = from node in doc.Descendants("MyLines")
                let attr = node.Attribute("Cache")
                where attr != null && Convert.ToInt32(attr.Value) == 16
                select node;
        q.ToList().ForEach(x => x.Remove());

Do you have a special reason to use LINQ? To me it looks like an XSL-transformation is the thing to do it... — ChriPf
– ChriPf, Commented Sep 11, 2012 at 9:05

smartcaveman · Accepted Answer · 2012-09-11 09:27:24Z

2

I have tested the following code:

string xml = 
@"<Category id=""1"">
<MyLines>
    <Line GroupID=""0"" Cache=""15"" />
<Rect GroupID=""0"" Cache=""16""/>
<Ellipse GroupID=""0"" Cache=""16""/>
</MyLines>
</Category>";

void Main()
{
    var doc = XDocument.Parse(xml);

    doc.Descendants("MyLines")
    .Elements()
    .Where(el => el.Attribute("Cache").Value == "16") 
    .ToList()
    .ForEach(el => el.Remove());

    doc.Root.ToString().Dump();
}

It prints:

<Category id="1">
   <MyLines>
      <Line GroupID="0" Cache="15" />
   </MyLines>
</Category>

The problem is that you were looking for the Cache attribute on the MyLines elements instead of on the MyLines elements' children.

edited Sep 11, 2012 at 9:27

answered Sep 11, 2012 at 9:05

smartcaveman

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3 Comments

smartcaveman Over a year ago

@KishoreBorra, I don't know if there was a typo in my original post, but I tested it and reposted. Try the updated code

Kishore Borra Over a year ago

Yes. The above code is working. But in my case I have multiple Category tags with a parent tag with a name <MyDocument xmlns="urn:Mylines.xsd" >. would it be creating any problem?

Kishore Borra Over a year ago

I figured out the solution. Yes the namespace would cause an issue while querying. It needs to be queried little differently. Please refer to the below link. social.msdn.microsoft.com/forums/en-US/linqprojectgeneral/…

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