DataContractSerializer.IsStartObject Method

Definition

Namespace:

System.Runtime.Serialization

Assembly:

System.Runtime.Serialization.Xml.dll

Determines whether the reader is positioned on an object that can be deserialized.

Overloads

IsStartObject(XmlReader)	Determines whether the XmlReader is positioned on an object that can be deserialized.
IsStartObject(XmlDictionaryReader)	Determines whether the XmlDictionaryReader is positioned on an object that can be deserialized.

IsStartObject(XmlReader)

Source:

DataContractSerializer.cs

Determines whether the XmlReader is positioned on an object that can be deserialized.

public:
 override bool IsStartObject(System::Xml::XmlReader ^ reader);

public override bool IsStartObject (System.Xml.XmlReader reader);

override this.IsStartObject : System.Xml.XmlReader -> bool

Public Overrides Function IsStartObject (reader As XmlReader) As Boolean

Parameters

reader

XmlReader

The XmlReader used to read the XML stream.

Returns

Boolean

true if the reader is at the start element of the stream to read; otherwise, false.

IsStartObject(XmlDictionaryReader)

Source:

DataContractSerializer.cs

Determines whether the XmlDictionaryReader is positioned on an object that can be deserialized.

public:
 override bool IsStartObject(System::Xml::XmlDictionaryReader ^ reader);

public override bool IsStartObject (System.Xml.XmlDictionaryReader reader);

override this.IsStartObject : System.Xml.XmlDictionaryReader -> bool

Public Overrides Function IsStartObject (reader As XmlDictionaryReader) As Boolean

Parameters

reader

XmlDictionaryReader

An XmlDictionaryReader used to read the XML stream.

Returns

Boolean

true if the reader is at the start element of the stream to read; otherwise, false.

Examples

The following example uses the IsStartObject property to determine whether the start of the data has been found.

public static void ReadObjectData(string path)
{
    // Create the reader.
    FileStream fs = new FileStream(path, FileMode.Open);
    XmlDictionaryReader reader =
        XmlDictionaryReader.CreateTextReader(fs, new XmlDictionaryReaderQuotas());

    // Create the DataContractSerializer specifying the type,
    // root and namespace to use. The root value corresponds
    // to the DataContract.Name value, and the namespace value
    // corresponds to the DataContract.Namespace value.
    DataContractSerializer ser =
        new DataContractSerializer(typeof(Person),
        "Customer", @"http://www.contoso.com");

    // Test if the serializer is on the start of the
    // object data. If so, read the data and write it
    // to the console.
    while (reader.Read())
    {
        if (ser.IsStartObject(reader))
        {
            Console.WriteLine("Found the element");
            Person p = (Person)ser.ReadObject(reader);
            Console.WriteLine("{0} {1}    id:{2}",
                p.FirstName, p.LastName, p.ID);
        }

        Console.WriteLine(reader.Name);
        break;
    }
    fs.Flush();
    fs.Close();
}

Public Shared Sub ReadObjectData(ByVal path As String) 
    ' Create the reader.
    Dim fs As New FileStream(path, FileMode.Open)
    Dim reader As XmlDictionaryReader = _
        XmlDictionaryReader.CreateTextReader(fs, New XmlDictionaryReaderQuotas())
    
    ' Create the DataContractSerializer specifying the type, 
    ' root and namespace to use. The root value corresponds
    ' to the DataContract.Name value, and the namespace value
    ' corresponds to the DataContract.Namespace value.
    Dim ser As New DataContractSerializer(GetType(Person), _
        "Customer", "http://www.contoso.com")
    
    ' Test if the serializer is on the start of the 
    ' object data. If so, read the data and write it 
    ' to the console.
    While reader.Read()
        If ser.IsStartObject(reader) Then
            Console.WriteLine("Found the element")
            Dim p As Person = CType(ser.ReadObject(reader), Person)
            Console.WriteLine("{0} {1}    id:{2}", p.FirstName, p.LastName, p.ID)
        End If
                
        Console.WriteLine(reader.Name)
    End While
    
    fs.Flush()
    fs.Close()

End Sub

Remarks

The IsStartObject determines whether it can read an object by checking that it is positioned on an XML element. It also examines the name and namespace of the XML element that the reader is positioned at and compares the values to the expected name and namespace. The expected name and namespace can be set with the following: the data contract name and namespace of the type passed into the constructor, or the rootName and rootNamespace values passed into the constructor (if present).