XPathQueryGenerator XPathQueryGenerator XPathQueryGenerator XPathQueryGenerator Class

定義

當提供代表資料合約的類別,以及代表合約成員的中繼資料時,會產生該成員的 XPath 查詢。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
繼承
XPathQueryGeneratorXPathQueryGeneratorXPathQueryGeneratorXPathQueryGenerator

範例

下列範例會從兩個類別建立 XPath 查詢,這兩個類別均已套用 DataContractAttributeDataMemberAttribute 屬性。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
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

備註

如需有關資料合約的詳細資訊,請參閱Using Data ContractsFor more information about data contracts, see Using Data Contracts.

使用類別有四個步驟:To use the class, there are four steps:

  1. 視需要,將 DataContractAttributeDataMemberAttribute 套用至型別及其欄位或屬性,以建立資料合約型別。Create the data contract type by applying the DataContractAttribute and DataMemberAttribute as appropriate to the type and its fields or properties.

  2. 使用 GetMember 類別的 Type 方法產生 MemberInfo 陣列。Use the GetMember method of the Type class to generate the MemberInfo array.

  3. 將型別及陣列貼至方法。Pass the type and the array to the method.

  4. 如有需要,請使用 XmlNamespaceManager 參數所傳回的 namespaces 檢查 XPath 查詢中的命名空間前置詞參考的 XML 命名空間。If needed, use the XmlNamespaceManager returned by the namespaces parameter to examine the XML namespaces referenced by the namespaces prefixes in the XPath query.

注意

XPath 中預設會使用命名空間前置詞 "xg" (表示「XPath 產生器」)。The namespace prefix "xg" (for "XPath Generator") is used as the default in the XPath. 這項設定無法變更。This cannot be changed. 請改為參考 NameTable 集合,查看與該前置詞關聯的命名空間。Instead, refer to the NameTable collection to see what namespace the prefix is associated with.

方法

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

使用指定的資料合約類型、中繼資料項目陣列及命名空間,從資料合約建立 XPath。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)

使用指定的資料合約型別、中繼資料項目陣列、最上層項目及命名空間,從資料合約建立 XPath。Creates an XPath from a data contract using the specified contract data type, array of metadata elements, the top level element, and namespaces.

適用於