DataSet.ReadXml Method (String, XmlReadMode)
Assembly: System.Data (in system.data.dll)
'Declaration Public Function ReadXml ( _ fileName As String, _ mode As XmlReadMode _ ) As XmlReadMode 'Usage Dim instance As DataSet Dim fileName As String Dim mode As XmlReadMode Dim returnValue As XmlReadMode returnValue = instance.ReadXml(fileName, mode)
The filename (including the path) from which to read.
One of the XmlReadMode values.
Return ValueThe XmlReadMode used to read the data.
The ReadXml method provides a way to read either data only, or both data and schema into a DataSet from an XML document, whereas the ReadXmlSchema method reads only the schema. To read both data and schema, use one of the ReadXML overloads that includes the mode parameter, and set its value to ReadSchema.
Note that the same is true for the WriteXml and WriteXmlSchema methods, respectively. To write XML data, or both schema and data from the DataSet, use the WriteXml method. To write just the schema, use the WriteXmlSchema method.
If an in-line schema is specified, the in-line schema is used to extend the existing relational structure prior to loading the data. If there are any conflicts (for example, the same column in the same table defined with different data types) an exception is raised.
If no in-line schema is specified, the relational structure is extended through inference, as necessary, according to the structure of the XML document. If the schema cannot be extended through inference in order to expose all data, an exception is raised.
The DataSet does not associate an XML elementwith its corresponding DataColumn or DataTable when legal XML characters like ("_") are escaped in the serialized XML. The DataSet itself only escapes illegal XML characters in XML element names and hence can only consume the same. When legal characters in XML element name are escaped, the element is ignored while processing.
If the XML Schema for a DataSet includes a targetNamespace, data may not be read, and you may encounter exceptions when calling ReadXml to load the DataSet with XML that contains elements with no qualifying namespace. To read unqualified elements, set elementFormDefault equal to "qualified" in your XML Schema as the following example demonstrates.
<xsd:schema id="MyDataSet" elementFormDefault="qualified" targetNamespace="http://www.tempuri.org/MyDataSet.xsd" xmlns="http://www.tempuri.org/MyDataSet.xsd" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:msdata="urn:schemas-microsoft-com:xml-msdata"> </xsd:schema>
If the schema for your DataSet contains elements of the same name, but different type, in the same namespace, an exception is thrown when you attempt to read the schema into the DataSet with ReadXml by specifying XmlReadMode.ReadSchema. This exception does not occur if you are using .NET Framework version 1.0.
- FileIOPermission for reading and writing files. Associated enumeration: FileIOPermissionAccess
Windows 98, Windows Server 2000 SP4, Windows CE, Windows Millennium Edition, Windows Mobile for Pocket PC, Windows Mobile for Smartphone, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter EditionThe Microsoft .NET Framework 3.0 is supported on Windows Vista, Microsoft Windows XP SP2, and Windows Server 2003 SP1.