XAttribute.Value Property
Important
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Gets or sets the value of this attribute.
public:
property System::String ^ Value { System::String ^ get(); void set(System::String ^ value); };public string Value { get; set; }member this.Value : string with get, setPublic Property Value As StringA String containing the value of this attribute.
When setting, the value is null.
The following example creates an element with an attribute. It then retrieves the value of the attribute, and then sets it.
Note that the Visual Basic example uses the XML attribute property.
XElement root = new XElement("Root",
new XAttribute("Att", "content")
);
XAttribute att = root.FirstAttribute;
Console.WriteLine(att.Value);
att.Value = "new text";
Console.WriteLine(att.Value);
Dim root As XElement = <Root Att="content"/>
Console.WriteLine(root.@Att)
root.@Att = "new text"
Console.WriteLine(root.@Att)
This example produces the following output:
content
new text
The following example shows the benefit of using the explicit conversion operators to get the value of an attribute that might not exist:
XElement root = new XElement("Root",
new XAttribute("Att1", "attribute 1 content"),
new XAttribute("Att2", "2")
);
// The following assignments demonstrate why it is easier to use
// casting when the attribute might or might not exist.
string c1 = (string)root.Attribute("Att1");
Console.WriteLine("c1:{0}", c1 == null ? "attribute does not exist" : c1);
int? c2 = (int?)root.Attribute("Att2");
Console.WriteLine("c2:{0}", c2 == null ? "attribute does not exist" : c2.ToString());
string c3 = (string)root.Attribute("Att3");
Console.WriteLine("c3:{0}", c3 == null ? "attribute does not exist" : c3);
int? c4 = (int?)root.Attribute("Att4");
Console.WriteLine("c4:{0}", c4 == null ? "attribute does not exist" : c4.ToString());
Console.WriteLine();
// The following assignments show the necessary code when using
// the value property when the attribute might or might not exist.
XAttribute att1 = root.Attribute("Att1");
string v1;
if (att1 == null)
v1 = null;
else
v1 = att1.Value;
Console.WriteLine("v1:{0}", v1 == null ? "attribute does not exist" : v1);
XAttribute att2 = root.Attribute("Att2");
int? v2;
if (att2 == null)
v2 = null;
else
v2 = Int32.Parse(att2.Value);
Console.WriteLine("v2:{0}", v2 == null ? "attribute does not exist" : v2.ToString());
XAttribute att3 = root.Attribute("Att3");
string v3;
if (att3 == null)
v3 = null;
else
v3 = att3.Value;
Console.WriteLine("v3:{0}", v3 == null ? "attribute does not exist" : v3);
XAttribute att4 = root.Attribute("Att4");
int? v4;
if (att4 == null)
v4 = null;
else
v4 = Int32.Parse(att4.Value);
Console.WriteLine("v4:{0}", v4 == null ? "attribute does not exist" : v4.ToString());
Dim root As XElement = <Root Att1="attribute 1 content" Att2="2"/>
' The following assignments demonstrate why it is easier to use
' casting when the attribute might or might not exist.
Dim c1 As String = CStr(root.Attribute("Att1"))
Console.WriteLine("c1:{0}", IIf(c1 Is Nothing, "attribute does not exist", c1))
Dim c2 As Nullable(Of Integer) = CType(root.Attribute("Att2"), Nullable(Of Integer))
Console.WriteLine("c2:{0}", IIf(c2.HasValue, c2, "attribute does not exist"))
Dim c3 As String = CStr(root.Attribute("Att3"))
Console.WriteLine("c3:{0}", IIf(c3 Is Nothing, "attribute does not exist", c3))
Dim c4 As Nullable(Of Integer) = CType(root.Attribute("Att4"), Nullable(Of Integer))
Console.WriteLine("c4:{0}", IIf(c4.HasValue, c4, "attribute does not exist"))
Console.WriteLine()
' The following assignments show the necessary code when using
' the value property when the attribute might or might not exist.
Dim att1 As XAttribute = root.Attribute("Att1")
Dim v1 As String
If att1 Is Nothing Then
v1 = Nothing
Else
v1 = att1.Value
End If
Console.WriteLine("v1:{0}", IIf(v1 Is Nothing, "attribute does not exist", v1))
Dim att2 As XAttribute = root.Attribute("Att2")
Dim v2 As Nullable(Of Integer)
If att2 Is Nothing Then
v2 = Nothing
Else
v2 = Int32.Parse(att2.Value)
End If
Console.WriteLine("v2:{0}", IIf(v2.HasValue, v2, "attribute does not exist"))
Dim att3 As XAttribute = root.Attribute("Att3")
Dim v3 As String
If att3 Is Nothing Then
v3 = Nothing
Else
v3 = att3.Value
End If
Console.WriteLine("v3:{0}", IIf(v3 Is Nothing, "attribute does not exist", v3))
Dim att4 As XAttribute = root.Attribute("Att4")
Dim v4 As Nullable(Of Integer)
If att4 Is Nothing Then
v4 = Nothing
Else
v4 = Int32.Parse(att4.Value)
End If
Console.WriteLine("v4:{0}", IIf(v4.HasValue, v4, "attribute does not exist"))
This example produces the following output:
c1:attribute 1 content
c2:2
c3:attribute does not exist
c4:attribute does not exist
v1:attribute 1 content
v2:2
v3:attribute does not exist
v4:attribute does not exist
You can use this property to get or set the value of an attribute.
Setting this property will raise the Changed and the Changing events.
If you are getting the value and the attribute might not exist, it is more convenient to use the explicit conversion operators, and assign the attribute to a nullable type such as string or Nullable<T> of Int32. If the attribute does not exist, then the nullable type is set to null. Before using this property, you must make sure that the Attribute method does not return null.
| Product | Versions |
|---|---|
| .NET | Core 1.0, Core 1.1, Core 2.0, Core 2.1, Core 2.2, Core 3.0, Core 3.1, 5, 6, 7, 8, 9, 10 |
| .NET Framework | 3.5, 4.0, 4.5, 4.5.1, 4.5.2, 4.6, 4.6.1, 4.6.2, 4.7, 4.7.1, 4.7.2, 4.8, 4.8.1 |
| .NET Standard | 1.0, 1.1, 1.2, 1.3, 1.4, 1.6, 2.0, 2.1 |
| UWP | 10.0 |
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