LINQ to XML C# get root element attribute

Question

Lts say i have XElement object doc:

<parameters mode="solve">
  <inputs>
    <a>value_a</a>
      ...
       ...

how do i get the value of the attribute of the first element (parameters), in other words how do i check which mode is it on.

if i write

if ((string)doc.Element("parameters").Attribute("mode").Value == "solve") { mode = 1; }

it gives me null object reference error

Can you add a short but complete program that demonstrates the problem? — dtb
– dtb, Commented Aug 17, 2011 at 14:55
i` mafraid i can`t, the thing is it gives me null object reference error but if i add another element above <parameters it works — pingve
– pingve, Commented Aug 17, 2011 at 14:57

Frédéric Hamidi · Accepted Answer · 2011-08-17 14:57:37Z

5

If doc is an XElement, as you say in your question, then you probably don't need to match it again:

if (doc.Attribute("mode").Value.ToString() == "solve") {
    mode = 1;
}

If it is an XDocument, then you can use its Root property to refer to the document element:

if (doc.Root.Attribute("mode").Value.ToString() == "solve") {
    mode = 1;
}

answered Aug 17, 2011 at 14:57

Frédéric Hamidi

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Ed Schwehm · Accepted Answer · 2011-08-17 15:01:21Z

0

When you are calling doc.Element("parameters"), you are trying to look at the elements below the root element (in this case, the elements at the same level as <inputs>). You want to do this instead:

if (input.Attribute("mode").Value == "solve") { mode = 1; }

answered Aug 17, 2011 at 15:01

Ed Schwehm

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Comments

sloth · Accepted Answer · 2012-08-02 12:23:52Z

0

Just use the Root

if (doc.Root.Attribute("mode").Value.Equals("solve"))
{
   mode = 1;
}

edited Aug 2, 2012 at 12:23

sloth

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answered Aug 17, 2011 at 14:57

msarchet

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