DataSet.GetXml Método
Definición
Importante
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Devuelve la representación XML de los datos almacenados en DataSet.
public:
System::String ^ GetXml();public string GetXml ();member this.GetXml : unit -> stringPublic Function GetXml () As StringDevoluciones
Cadena que es una representación de los datos almacenados en DataSet.
Ejemplos
En el ejemplo siguiente se crea y DataSetDataTable, se agregan datos de ejemplo y, a continuación, se muestran los datos en formato XML.
private static void DemonstrateGetXml()
{
// Create a DataSet with one table containing
// two columns and 10 rows.
DataSet dataSet = new DataSet("dataSet");
DataTable table = dataSet.Tables.Add("Items");
table.Columns.Add("id", typeof(int));
table.Columns.Add("Item", typeof(string));
// Add ten rows.
DataRow row;
for(int i = 0; i <10;i++)
{
row = table.NewRow();
row["id"]= i;
row["Item"]= "Item" + i;
table.Rows.Add(row);
}
// Display the DataSet contents as XML.
Console.WriteLine( dataSet.GetXml() );
}
Private Shared Sub DemonstrateGetXml()
' Create a DataSet with one table
' containing two columns and 10 rows.
Dim dataSet As New DataSet("dataSet")
Dim table As DataTable = dataSet.Tables.Add("Items")
table.Columns.Add("id", Type.GetType("System.Int32"))
table.Columns.Add("Item", Type.GetType("System.String"))
' Add ten rows.
Dim row As DataRow
Dim i As Integer
For i = 0 To 9
row = table.NewRow()
row("id") = i
row("Item")= "Item" & i
table.Rows.Add(row)
Next
' Display the DataSet contents as XML.
Console.WriteLine( dataSet.GetXml() )
End Sub
En este ejemplo se muestra cómo escribir datos en un archivo XML desde un DataSet y leer datos en DataSet desde XML. En este ejemplo se creará un conjunto de datos con dos tablas, se usarán dos maneras de exportar un conjunto de datos a los archivos XML (WriteXml y GetXml) y usar dos maneras (ReadXml e InferXmlSchema) para importar un conjunto de datos de los archivos XML.
Antes de compilar y ejecutar el ejemplo, debe crear cuatro archivos XML en el directorio de ejemplo. En primer lugar, cree ElementsWithAttributes.xml:
<MySchool>
<Course CourseID="C1045" Year="2012" Title="Calculus" Credits="4" DepartmentID="7">New</Course>
<Course CourseID="C1061" Year="2012" Title="Physics" Credits="4" DepartmentID="1" />
<Department DepartmentID="1" Name="Engineering" Budget="350000" StartDate="2007-09-01T00:00:00+08:00" Administrator="2" />
<Department DepartmentID="7" Name="Mathematics" Budget="250024" StartDate="2007-09-01T00:00:00+08:00" Administrator="3">Cancelled</Department>
</MySchool>
A continuación, cree ElementsWithChildElementsxml.xml:
<MySchool>
<Course>
<CourseID>C1045</CourseID>
<Year>2012</Year>
<Title>Calculus</Title>
<Credits>4</Credits>
<DepartmentID>7</DepartmentID>
</Course>
<Course>
<CourseID>C1061</CourseID>
<Year>2012</Year>
<Title>Physics</Title>
<Credits>4</Credits>
<DepartmentID>1</DepartmentID>
</Course>
<Course>
<CourseID>C2021</CourseID>
<Year>2012</Year>
<Title>Composition</Title>
<Credits>3</Credits>
<DepartmentID>2</DepartmentID>
</Course>
<Course>
<CourseID>C2042</CourseID>
<Year>2012</Year>
<Title>Literature</Title>
<Credits>4</Credits>
<DepartmentID>2</DepartmentID>
</Course>
<Department>
<DepartmentID>1</DepartmentID>
<Name>Engineering</Name>
<Budget>350000</Budget>
<StartDate>2007-09-01T00:00:00+08:00</StartDate>
<Administrator>2</Administrator>
</Department>
<Department>
<DepartmentID>2</DepartmentID>
<Name>English</Name>
<Budget>120000</Budget>
<StartDate>2007-09-01T00:00:00+08:00</StartDate>
<Administrator>6</Administrator>
</Department>
<Department>
<DepartmentID>4</DepartmentID>
<Name>Economics</Name>
<Budget>200000</Budget>
<StartDate>2007-09-01T00:00:00+08:00</StartDate>
<Administrator>4</Administrator>
</Department>
<Department>
<DepartmentID>7</DepartmentID>
<Name>Mathematics</Name>
<Budget>250024</Budget>
<StartDate>2007-09-01T00:00:00+08:00</StartDate>
<Administrator>3</Administrator>
</Department>
</MySchool>
Ahora cree ElementsWithOnlyAttributes.xml:
<MySchool>
<Course CourseID="C1045" Year="2012" Title="Calculus" Credits="4" DepartmentID="7" />
<Course CourseID="C1061" Year="2012" Title="Physics" Credits="4" DepartmentID="1" />
<Department DepartmentID="1" Name="Engineering" Budget="350000" StartDate="2007-09-01T00:00:00+08:00" Administrator="2" />
<Department DepartmentID="7" Name="Mathematics" Budget="250024" StartDate="2007-09-01T00:00:00+08:00" Administrator="3" />
</MySchool>
Y, por último, cree RepeatingElements.xml:
<MySchool>
<Course>C1045</Course>
<Course>C1061</Course>
<Department>Engineering</Department>
<Department>Mathematics</Department>
</MySchool>
Ahora puede compilar y ejecutar el código fuente siguiente.
using System;
using System.Data;
using System.IO;
using System.Text;
using System.Xml;
// Use WriteXml method to export the dataset.
static class DataTableHelper {
public static void WriteDataSetToXML(DataSet dataset, String xmlFileName) {
using (FileStream fsWriterStream = new FileStream(xmlFileName, FileMode.Create)) {
using (XmlTextWriter xmlWriter = new XmlTextWriter(fsWriterStream, Encoding.Unicode)) {
dataset.WriteXml(xmlWriter, XmlWriteMode.WriteSchema);
Console.WriteLine("Write {0} to the File {1}.", dataset.DataSetName, xmlFileName);
Console.WriteLine();
}
}
}
// Use GetXml method to get the XML data of the dataset and then export to the file.
public static void GetXMLFromDataSet(DataSet dataset, String xmlFileName) {
using (StreamWriter writer = new StreamWriter(xmlFileName)) {
writer.WriteLine(dataset.GetXml());
Console.WriteLine("Get Xml data from {0} and write to the File {1}.", dataset.DataSetName, xmlFileName);
Console.WriteLine();
}
}
// Use ReadXml method to import the dataset from the dataset.
public static void ReadXmlIntoDataSet(DataSet newDataSet, String xmlFileName) {
using (FileStream fsReaderStream = new FileStream(xmlFileName, FileMode.Open)) {
using (XmlTextReader xmlReader = new XmlTextReader(fsReaderStream)) {
newDataSet.ReadXml(xmlReader, XmlReadMode.ReadSchema);
}
}
}
// Display the columns and value of DataSet.
public static void ShowDataSet(DataSet dataset) {
foreach (DataTable table in dataset.Tables) {
Console.WriteLine("Table {0}:", table.TableName);
ShowDataTable(table);
}
}
// Display the columns and value of DataTable.
private static void ShowDataTable(DataTable table) {
foreach (DataColumn col in table.Columns) {
Console.Write("{0,-14}", col.ColumnName);
}
Console.WriteLine("{0,-14}", "");
foreach (DataRow row in table.Rows) {
if (row.RowState == DataRowState.Deleted) {
foreach (DataColumn col in table.Columns) {
if (col.DataType.Equals(typeof(DateTime))) {
Console.Write("{0,-14:d}", row[col, DataRowVersion.Original]);
}
else if (col.DataType.Equals(typeof(Decimal))) {
Console.Write("{0,-14:C}", row[col, DataRowVersion.Original]);
}
else {
Console.Write("{0,-14}", row[col, DataRowVersion.Original]);
}
}
}
else {
foreach (DataColumn col in table.Columns) {
if (col.DataType.Equals(typeof(DateTime))) {
Console.Write("{0,-14:d}", row[col]);
}
else if (col.DataType.Equals(typeof(Decimal))) {
Console.Write("{0,-14:C}", row[col]);
}
else {
Console.Write("{0,-14}", row[col]);
}
}
}
Console.WriteLine("{0,-14}", "");
}
}
// Display the columns of DataSet.
public static void ShowDataSetSchema(DataSet dataSet) {
Console.WriteLine("{0} contains the following tables:", dataSet.DataSetName);
foreach (DataTable table in dataSet.Tables) {
Console.WriteLine(" Table {0} contains the following columns:", table.TableName);
ShowDataTableSchema(table);
}
}
// Display the columns of DataTable
private static void ShowDataTableSchema(DataTable table) {
String columnString = "";
foreach (DataColumn col in table.Columns) {
columnString += col.ColumnName + " ";
}
Console.WriteLine(columnString);
}
}
class Program {
static void Main(string[] args) {
// Create the DataSet
DataSet school = new DataSet("MySchool");
DataTable course = CreateCourse();
DataTable department = CreateDepartment();
school.Tables.Add(course);
school.Tables.Add(department);
// Define the constraint between the tables.
ForeignKeyConstraint courseDepartFK = new ForeignKeyConstraint("CourseDepartFK", department.Columns["DepartmentID"], course.Columns["DepartmentID"]);
courseDepartFK.DeleteRule = Rule.Cascade;
courseDepartFK.UpdateRule = Rule.Cascade;
courseDepartFK.AcceptRejectRule = AcceptRejectRule.None;
course.Constraints.Add(courseDepartFK);
InsertDepartments(department);
InsertCourses(course);
// Export the dataset to the XML file.
Console.WriteLine("Data of the whole DataSet {0}", school.DataSetName);
DataTableHelper.ShowDataSet(school);
String xmlWithSchemaFileName = "WriterXMLWithSchema.xml";
String xmlGetDataFileName = "GetXML.xml";
// Use two ways to export the dataset to the Xml file.
DataTableHelper.WriteDataSetToXML(school, xmlWithSchemaFileName);
DataTableHelper.GetXMLFromDataSet(school, xmlGetDataFileName);
// Import the dataset from the XML file.
// Use two ways to import the dataset from the Xml file.
Console.WriteLine("Read Xml document into a new DataSet:");
DataSet newSchool = new DataSet("NewSchool");
DataTableHelper.ReadXmlIntoDataSet(newSchool, xmlWithSchemaFileName);
DataTableHelper.ShowDataSetSchema(newSchool);
Console.WriteLine();
Console.WriteLine("Infer a schema for a DataSet from an XML document:");
InferDataSetSchemaFromXml();
Console.WriteLine("Press any key to exit.");
Console.ReadKey();
}
static DataTable CreateCourse() {
DataTable course = new DataTable("Course");
DataColumn[] cols ={
new DataColumn("CourseID",typeof(String)),
new DataColumn("Year",typeof(Int32)),
new DataColumn("Title",typeof(String)),
new DataColumn("Credits",typeof(Int32)),
new DataColumn("DepartmentID",typeof(Int32))};
course.Columns.AddRange(cols);
course.PrimaryKey = new DataColumn[] { course.Columns["CourseID"], course.Columns["Year"] };
return course;
}
static DataTable CreateDepartment() {
DataTable department = new DataTable("Department");
DataColumn[] cols = {
new DataColumn("DepartmentID", typeof(Int32)),
new DataColumn("Name",typeof(String)),
new DataColumn("Budget",typeof(Decimal)),
new DataColumn("StartDate",typeof(DateTime)),
new DataColumn("Administrator",typeof(Int32))};
department.Columns.AddRange(cols);
department.PrimaryKey = new DataColumn[] { department.Columns["DepartmentID"] };
return department;
}
static void InsertDepartments(DataTable department) {
Object[] rows = {
new Object[]{1,"Engineering",350000.00,new DateTime(2007,9,1),2},
new Object[]{2,"English",120000.00,new DateTime(2007,9,1),6},
new Object[]{4,"Economics",200000.00,new DateTime(2007,9,1),4},
new Object[]{7,"Mathematics",250024.00,new DateTime(2007,9,1),3}};
foreach (Object[] row in rows) {
department.Rows.Add(row);
}
}
static void InsertCourses(DataTable course) {
Object[] rows ={
new Object[]{"C1045",2012,"Calculus",4,7},
new Object[]{"C1061",2012,"Physics",4,1},
new Object[]{"C2021",2012,"Composition",3,2},
new Object[]{"C2042",2012,"Literature",4,2}};
foreach (Object[] row in rows) {
course.Rows.Add(row);
}
}
// Display the results of inferring schema from four types of XML structures
private static void InferDataSetSchemaFromXml() {
String[] xmlFileNames = {
@"ElementsWithOnlyAttributes.xml",
@"ElementsWithAttributes.xml",
@"RepeatingElements.xml",
@"ElementsWithChildElements.xml" };
foreach (String xmlFileName in xmlFileNames) {
Console.WriteLine("Result of {0}", Path.GetFileNameWithoutExtension(xmlFileName));
DataSet newSchool = new DataSet();
newSchool.InferXmlSchema(xmlFileName, null);
DataTableHelper.ShowDataSetSchema(newSchool);
Console.WriteLine();
}
}
}
Comentarios
Llamar a este método es idéntico a llamar a WriteXml con XmlWriteMode establecido en IgnoreSchema.
GetXml devuelve XML como una cadena y, por tanto, requiere más sobrecarga que WriteXml escribir XML en un archivo.
Si crea un DataSet mediante la inferencia de esquema y lo serializa mediante XML o servicios web, el orden de las columnas puede cambiar.
Se aplica a
Consulte también
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