XAttribute.Value Properti

public:
 property System::String ^ Value { System::String ^ get(); void set(System::String ^ value); };

public string Value { get; set; }

member this.Value : string with get, set

Public Property Value As String

Nilai Properti

yang String berisi nilai atribut ini.

Pengecualian

Contoh

Contoh berikut membuat elemen dengan atribut . Kemudian mengambil nilai atribut, lalu mengaturnya.

Perhatikan bahwa contoh Visual Basic menggunakan properti atribut XML.

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)

Contoh ini menghasilkan output berikut:

content
new text

Contoh berikut menunjukkan manfaat menggunakan operator konversi eksplisit untuk mendapatkan nilai atribut yang mungkin tidak ada:

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"))

Contoh ini menghasilkan output berikut:

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

Keterangan

Anda dapat menggunakan properti ini untuk mendapatkan atau mengatur nilai atribut.

Mengatur properti ini akan memunculkan ChangedChanging dan peristiwa.

Jika Anda mendapatkan nilai dan atribut mungkin tidak ada, lebih mudah untuk menggunakan operator konversi eksplisit, dan menetapkan atribut ke jenis nullable seperti string atau Nullable<T> dari Int32. Jika atribut tidak ada, maka jenis nullable diatur ke null. Sebelum menggunakan properti ini, Anda harus memastikan bahwa Attribute metode tidak mengembalikan null.

Lihat juga

• SetValue(Object)
• Name
• ToString()
• Gambaran umum LINQ ke XML