DataSet.GetXml Méthode

public:
 System::String ^ GetXml();

public string GetXml ();

member this.GetXml : unit -> string

Public Function GetXml () As String

Retours

Chaîne qui est une représentation des données stockées dans le DataSet.

Exemples

L’exemple suivant crée un et DataTable, ajoute des DataSet exemples de données, puis affiche les données au format 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

Cet exemple montre comment écrire des données dans un fichier XML à partir d’un DataSet et lire des données dans DataSet à partir de XML. Cet exemple crée un jeu de données avec deux tables, utilise deux façons d’exporter un jeu de données dans les fichiers XML (WriteXml et GetXml) et utilise deux méthodes (ReadXml et InferXmlSchema) pour importer un jeu de données à partir des fichiers XML.

Avant de compiler et d’exécuter l’exemple, vous devez créer quatre fichiers XML dans l’exemple de répertoire. Tout d’abord, créez 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>

Ensuite, créez 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>

Créez maintenant 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>

Enfin, créez RepeatingElements.xml :

<MySchool>
  <Course>C1045</Course>
  <Course>C1061</Course>
  <Department>Engineering</Department>
  <Department>Mathematics</Department>
</MySchool>

Vous pouvez maintenant compiler et exécuter le code source suivant.

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();
      }
   }
}

Remarques

L’appel de cette méthode est identique à l’appel WriteXml avec XmlWriteMode défini sur IgnoreSchema.

GetXml retourne du code XML sous forme de chaîne et nécessite donc plus de surcharge que WriteXml pour écrire du CODE XML dans un fichier.

Si vous générez un à l’aide de DataSet l’inférence de schéma et que vous le sérialisez à l’aide de services XML ou Web, l’ordre des colonnes peut changer.

S’applique à

Voir aussi

• Utilisation de DataSets dans ADO.NET