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How to retrieve the value of an element (LINQ to XML)

  • Article

This article shows how to get the value of elements. There are two main ways to get the value:

  • Cast an XElement or an XAttribute to the desired type. The explicit conversion operator then converts the contents of the element or attribute to the specified type and assigns it to your variable.

  • Use the XElement.Value or XAttribute.Value properties. You can also set the value using these properties.

With C#, casting is generally the better approach. If you cast the element or attribute to a nullable value type, the code is simpler to write when retrieving the value of an element (or attribute) that may not exist. The last example in this article demonstrates this. However, you can't set the contents of an element through casting, as you can through XElement.Value property.

With Visual Basic, the better approach is to use the XElement.Value property.

String cast example

To retrieve the value of an element, cast the XElement object to your desired type. You can cast an element to a string, as follows:

XElement e = new XElement("StringElement", "abcde");
Console.WriteLine(e);
Console.WriteLine("Value of e:" + (string)e);

Dim e As XElement = <StringElement>abcde</StringElement>
Console.WriteLine(e)
Console.WriteLine("Value of e:" & e.Value)

This example produces the following output:

<StringElement>abcde</StringElement>
Value of e:abcde

Integer cast example

You can also cast elements to types other than string. For example, if you have an element that contains an integer, you can cast it to int, as shown in the following code:

XElement e = new XElement("Age", "44");
Console.WriteLine(e);
Console.WriteLine("Value of e:" + (int)e);

Dim e As XElement = <Age>44</Age>
Console.WriteLine(e)
Console.WriteLine("Value of e:" & CInt(e))

This example produces the following output:

<Age>44</Age>
Value of e:44

LINQ to XML provides explicit cast operators for the following data types: string, bool, bool?, int, int?, uint, uint?, long, long?, ulong, ulong?, float, float?, double, double?, decimal, decimal?, DateTime, DateTime?, TimeSpan, TimeSpan?, GUID, and GUID?.

LINQ to XML provides the same cast operators for XAttribute objects.

Value property example

You can use the Value property to retrieve the contents of an element:

XElement e = new XElement("StringElement", "abcde");
Console.WriteLine(e);
Console.WriteLine("Value of e:" + e.Value);

Dim e As XElement = <StringElement>abcde</StringElement>
Console.WriteLine(e)
Console.WriteLine("Value of e:" & e.Value)

This example produces the following output:

<StringElement>abcde</StringElement>
Value of e:abcde

Element might not exist example

Sometimes you try to retrieve the value of an element even though you're not sure if it exists. In this case, when you assign the casted element to a nullable reference type or nullable value type, if the element doesn't exist, the assigned variable is set to null (C#) or nothing (Visual Basic). The following code shows that when the element may not exist, it's easier to use casting than to use the Value property.

XElement root = new XElement("Root",
    new XElement("Child1", "child 1 content"),
    new XElement("Child2", "2")
);

// The following assignments show why it's easier to use
// casting when the element might or might not exist.

string c1 = (string)root.Element("Child1");
Console.WriteLine("c1:{0}", c1 == null ? "element doesn't exist" : c1);

int? c2 = (int?)root.Element("Child2");
Console.WriteLine("c2:{0}", c2 == null ? "element doesn't exist" : c2.ToString());

string c3 = (string)root.Element("Child3");
Console.WriteLine("c3:{0}", c3 == null ? "element doesn't exist" : c3);

int? c4 = (int?)root.Element("Child4");
Console.WriteLine("c4:{0}", c4 == null ? "element doesn't exist" : c4.ToString());

Console.WriteLine();

// The following assignments show the required code when using
// the Value property when the element might or might not exist.
// Notice that this is more difficult than the casting approach.

XElement e1 = root.Element("Child1");
string v1;
if (e1 == null)
    v1 = null;
else
    v1 = e1.Value;
Console.WriteLine("v1:{0}", v1 == null ? "element doesn't exist" : v1);

XElement e2 = root.Element("Child2");
int? v2;
if (e2 == null)
    v2 = null;
else
    v2 = Int32.Parse(e2.Value);
Console.WriteLine("v2:{0}", v2 == null ? "element doesn't exist" : v2.ToString());

XElement e3 = root.Element("Child3");
string v3;
if (e3 == null)
    v3 = null;
else
    v3 = e3.Value;
Console.WriteLine("v3:{0}", v3 == null ? "element doesn't exist" : v3);

XElement e4 = root.Element("Child4");
int? v4;
if (e4 == null)
    v4 = null;
else
    v4 = Int32.Parse(e4.Value);
Console.WriteLine("v4:{0}", v4 == null ? "element doesn't exist" : v4.ToString());

Dim root As XElement = <Root>
                           <Child1>child 1 content</Child1>
                           <Child2>2</Child2>
                       </Root>

' The following assignments show why it's easier to use
' casting when the element might or might not exist.

Dim c1 As String = CStr(root.Element("Child1"))
Console.WriteLine("c1:{0}", IIf(c1 Is Nothing, "element doesn't exist", c1))

Dim c2 As Nullable(Of Integer) = CType(root.Element("Child2"), Nullable(Of Integer))
Console.WriteLine("c2:{0}", IIf(Not (c2.HasValue), "element doesn't exist", c2.ToString()))

Dim c3 As String = CStr(root.Element("Child3"))
Console.WriteLine("c3:{0}", IIf(c3 Is Nothing, "element doesn't exist", c3))

Dim c4 As Nullable(Of Integer) = CType(root.Element("Child4"), Nullable(Of Integer))
Console.WriteLine("c4:{0}", IIf(Not (c4.HasValue), "element doesn't exist", c4.ToString()))

Console.WriteLine()

' The following assignments show the required code when using
' the Value property when the attribute might or might not exist.
' Notice that this is more difficult than the casting approach.

Dim e1 As XElement = root.Element("Child1")
Dim v1 As String
If (e1 Is Nothing) Then
    v1 = Nothing
Else
    v1 = e1.Value
End If
Console.WriteLine("v1:{0}", IIf(v1 Is Nothing, "element doesn't exist", v1))

Dim e2 As XElement = root.Element("Child2")
Dim v2 As Nullable(Of Integer)
If (e2 Is Nothing) Then
    v2 = Nothing
Else
    v2 = e2.Value
End If
Console.WriteLine("v2:{0}", IIf(Not (v2.HasValue), "element doesn't exist", v2))

Dim e3 As XElement = root.Element("Child3")
Dim v3 As String
If (e3 Is Nothing) Then
    v3 = Nothing
Else
    v3 = e3.Value
End If
Console.WriteLine("v3:{0}", IIf(v3 Is Nothing, "element doesn't exist", v3))

Dim e4 As XElement = root.Element("Child4")
Dim v4 As Nullable(Of Integer)
If (e4 Is Nothing) Then
    v4 = Nothing
Else
    v4 = e4.Value
End If
Console.WriteLine("v4:{0}", IIf(Not (v4.HasValue), "element doesn't exist", v4))

This example produces the following output:

c1:child 1 content
c2:2
c3:element doesn't exist
c4:element doesn't exist

v1:child 1 content
v2:2
v3:element doesn't exist
v4:element doesn't exist

In general, you can write simpler code by casting to retrieve the contents of elements and attributes.

See also