XPathQueryGenerator XPathQueryGenerator XPathQueryGenerator XPathQueryGenerator Class

Definición

Cuando se da una clase que representa un contrato de datos y metadatos que representan un miembro del contrato, se produce una consulta XPath para el miembro.When given a class representing a data contract, and metadata representing a member of the contract, produces an XPath query for the member.

public ref class XPathQueryGenerator abstract sealed
public static class XPathQueryGenerator
type XPathQueryGenerator = class
Public Class XPathQueryGenerator
Herencia
XPathQueryGeneratorXPathQueryGeneratorXPathQueryGeneratorXPathQueryGenerator

Ejemplos

En el siguiente ejemplo se crean las consultas XPath a partir de dos clases a las que se han aplicado los atributos DataContractAttribute y DataMemberAttribute.The following example creates XPath queries from two classes to which the DataContractAttribute and DataMemberAttribute attributes have been applied.

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Reflection;
using System.Runtime.Serialization;
using System.Xml;

namespace GeneratPathExample
{
    class Program
    {
        static void Main(string[] args)
        {
            // Get the type of the class that defines the data contract.
            Type t = typeof(Order);

            // Get the meta data for the specific members to be used in the query.
            MemberInfo[] mi = t.GetMember("Product");
            MemberInfo[] mi2 = t.GetMember("Value");
            MemberInfo[] mi3 = t.GetMember("Quantity");

            // Call the function below to generate and display the query.
            GenerateXPath(t, mi);
            GenerateXPath(t, mi2);
            GenerateXPath(t, mi3);


            // Get the type of the second class that defines a data contract.
            Type t2 = typeof(Line);

            // Get the meta data for the member to be used in the query.
            MemberInfo[] mi4 = t2.GetMember("Items");
            
            GenerateXPath(t2, mi4);

            Console.ReadLine();
        }

        static void GenerateXPath(Type t, MemberInfo[] mi)
        {

            // Create a new name table and name space manager.
            NameTable nt = new NameTable();
            XmlNamespaceManager xname = new XmlNamespaceManager(nt);


            // Generate the query and print it.
            string query = XPathQueryGenerator.CreateFromDataContractSerializer(
                t, mi, out xname);
            Console.WriteLine(query);
            Console.WriteLine();


            // Display the namespaces and prefixes used in the data contract.
            foreach (string s in xname)
                Console.WriteLine("{0}  = {1}", s, xname.LookupNamespace(s));
           
            Console.WriteLine();       

        }
    }

    [DataContract(Namespace = "http://www.cohowinery.com/")]
    public class Line
    {
        private Order[] itemsValue;

        [DataMember]
        public Order[] Items
        {
            get { return itemsValue; }
            set { itemsValue = value; }
        }

    }

    [DataContract(Namespace = "http://contoso.com")]
    public class Order
    {
        private string productValue;
        private int quantityValue;
        private decimal valueValue;

        [DataMember(Name = "cost")]
        public decimal Value
        {
            get { return valueValue; }
            set { valueValue = value; }
        }

        [DataMember(Name = "quantity")]
        public int Quantity
        {
            get { return quantityValue; }
            set { quantityValue = value; }
        }

        [DataMember(Name = "productName")]
        public string Product
        {
            get { return productValue; }
            set { productValue = value; }
        }
    }
}
Imports System.Collections.Generic
Imports System.Linq
Imports System.Text
Imports System.Reflection
Imports System.Runtime.Serialization
Imports System.Xml

Namespace GeneratPathExample

    Class Program

        Shared Sub Main(ByVal args As String())

            ' Get the type of the class that defines the data contract.
            Dim t As Type = GetType(Order)

            ' Get the meta data for the specific members to be used in the query.
            Dim mi As MemberInfo() = t.GetMember("Product")
            Dim mi2 As MemberInfo() = t.GetMember("Value")
            Dim mi3 As MemberInfo() = t.GetMember("Quantity")

            ' Call the function below to generate and display the query.
            GenerateXPath(t, mi)
            GenerateXPath(t, mi2)
            GenerateXPath(t, mi3)


            ' Get the type of the second class that defines a data contract.
            Dim t2 As Type = GetType(Line)

            ' Get the meta data for the member to be used in the query.
            Dim mi4 As MemberInfo() = t2.GetMember("Items")

            GenerateXPath(t2, mi4)

            Console.ReadLine()
        End Sub

        Shared Sub GenerateXPath(ByVal t As Type, ByVal mi As MemberInfo())


            ' Create a new name table and name space manager.
            Dim nt As New NameTable()
            Dim xname As New XmlNamespaceManager(nt)


            ' Generate the query and print it.
            Dim query As String = XPathQueryGenerator.CreateFromDataContractSerializer( _
                t, mi, xname)
            Console.WriteLine(query)
            Console.WriteLine()


            ' Display the namespaces and prefixes used in the data contract.
            Dim s As String
            For Each s In xname
                Console.WriteLine("{0}  = {1}", s, xname.LookupNamespace(s))
            Next

            Console.WriteLine()

        End Sub
    End Class


    <DataContract(Namespace:="http://www.cohowinery.com/")> _
        Public Class Line

        Private itemsValue As Order()

        <DataMember()>
        Public Property Item() As Order()

            Get
                Return itemsValue
            End Get
            Set(ByVal value As Order())
                itemsValue = value
            End Set
        End Property

    End Class

    <DataContract(Namespace:="http://contoso.com")> _
    Public Class Order

        Private productValue As String
        Private quantityValue As Integer
        Private valueValue As Decimal

        <DataMember(Name:="cost")>
        Public Property Value() As String

            Get
                Return valueValue
            End Get
            Set(ByVal value As String)
                valueValue = value
            End Set
        End Property

        <DataMember(Name:="quantity")> _
        Public Property Quantity() As Integer

            Get
                Return quantityValue
            End Get
            set(ByVal value As Integer)
                quantityValue = value
            End Set
        End Property


        <DataMember(Name:="productName")> _
        Public Property Product() As String

            Get
                Return productValue
            End Get
            Set(ByVal value As String)
                productValue = value
            End Set
        End Property
    End Class
End Namespace

Comentarios

Para obtener más información sobre los contratos de datos, consulte uso de contratos de datos.For more information about data contracts, see Using Data Contracts.

Para utilizar la clase, hay cuatro pasos:To use the class, there are four steps:

  1. Cree el tipo de contrato de datos aplicando el atributo DataContractAttribute y DataMemberAttribute al tipo y sus campos o propiedades según corresponda.Create the data contract type by applying the DataContractAttribute and DataMemberAttribute as appropriate to the type and its fields or properties.

  2. Utilice el método GetMember de la clase Type para generar la matriz MemberInfo.Use the GetMember method of the Type class to generate the MemberInfo array.

  3. Pase el tipo y la matriz al método.Pass the type and the array to the method.

  4. Si es necesario, utilice el XmlNamespaceManager devuelto por el parámetro namespaces para examinar los espacios de nombres XML a los que hacen referencia los prefijos de espacios de nombres de la consulta XPath.If needed, use the XmlNamespaceManager returned by the namespaces parameter to examine the XML namespaces referenced by the namespaces prefixes in the XPath query.

Nota

El prefijo de espacio de nombres "xg" (para "Generador de XPath") se utiliza como valor predeterminado en el XPath.The namespace prefix "xg" (for "XPath Generator") is used as the default in the XPath. Esto no puede modificarse.This cannot be changed. En su lugar, vea la colección NameTable para ver con qué espacio de nombres esa asociado el prefijo.Instead, refer to the NameTable collection to see what namespace the prefix is associated with.

Métodos

CreateFromDataContractSerializer(Type, MemberInfo[], XmlNamespaceManager) CreateFromDataContractSerializer(Type, MemberInfo[], XmlNamespaceManager) CreateFromDataContractSerializer(Type, MemberInfo[], XmlNamespaceManager) CreateFromDataContractSerializer(Type, MemberInfo[], XmlNamespaceManager)

Crea un elemento XPath a partir de un contrato de datos con los elementos especificados (tipo de contrato de datos, matriz de elementos de metadatos y espacios de nombres).Creates an XPath from a data contract using the specified data contract type, array of metadata elements, and namespaces.

CreateFromDataContractSerializer(Type, MemberInfo[], StringBuilder, XmlNamespaceManager) CreateFromDataContractSerializer(Type, MemberInfo[], StringBuilder, XmlNamespaceManager) CreateFromDataContractSerializer(Type, MemberInfo[], StringBuilder, XmlNamespaceManager) CreateFromDataContractSerializer(Type, MemberInfo[], StringBuilder, XmlNamespaceManager)

Crea un XPath a partir de un contrato de datos mediante el tipo de datos del contrato, la matriz de elementos de metadatos, el elemento de nivel superior y los espacios de nombres especificados.Creates an XPath from a data contract using the specified contract data type, array of metadata elements, the top level element, and namespaces.

Se aplica a