[原创]谈谈WCF中的Data Contract（3）：WCF Data Contract对Collection & Dictionary的支持...

在本篇文章上一部分 Order Processing 的例子中，我们看到原本已 Collection 形式定义的 DetailList 属性（ public IList<TDetail> DetailList ），在 Data Contract 中却以 Array 的方式体现（ public OrderDetail[] DetailList ）。我们现在就来详细地讨论一下基于 Collection & Dictionary 的 Data Contract 。

Data Contract for Collection

我们照例用例子来说明问题，在这里我们创建一个批量处理Order的Service，于是我们创建了一个OrderCollection Type:

namespace Artech.SpecialDataContract.Contract
{
[DataContract]
publicclassOrder
{
[DataMember]
publicGuidOrderID
{get;set;}

[DataMember]
publicDateTimeOrderDate
{get;set;}
}

publicclassOrderCollection:List<Order>
{

}
}

下面是Service Contract的定义：

namespace Artech.SpecialDataContract.Contract
{
[ServiceContract]
publicinterfaceIOrderManager
{
[OperationContract(Name="ProcessWithCollection")]
voidProcess(OrderCollectionorders);
}

面是OrderCollection 在XSD中的呈现：

<? xmlversion="1.0"encoding="utf-8" ?>
< xs:schema elementFormDefault ="qualified" targetNamespace ="http://schemas.datacontract.org/2004/07/Artech.SpecialDataContract.Contract"
xmlns:xs ="http://www.w3.org/2001/XMLSchema" xmlns:tns ="http://schemas.datacontract.org/2004/07/Artech.SpecialDataContract.Contract"
xmlns:ser ="http://schemas.microsoft.com/2003/10/Serialization/" >
< xs:import schemaLocation ="http://artech/Artech.SpecialDataContract/OrderManagerService.svc?xsd=xsd1"
namespace ="http://schemas.microsoft.com/2003/10/Serialization/" />
< xs:complexType name ="ArrayOfOrder" >
< xs:sequence >
< xs:element minOccurs ="0" maxOccurs ="unbounded" name ="Order" nillable ="true" type ="tns:Order" />
</ xs:sequence >
</ xs:complexType >
< xs:element name ="ArrayOfOrder" nillable ="true" type ="tns:ArrayOfOrder" />
< xs:complexType
name ="Order" >
< xs:sequence >
< xs:element minOccurs ="0" name ="OrderDate" type ="xs:dateTime" />
< xs:element
minOccurs ="0" name ="OrderID" type ="ser:guid" />
</ xs:sequence >
</ xs:complexType >
< xs:element
name ="Order" nillable ="true" type ="tns:Order" />
</ xs:schema >

加上通过Add Service Reference默认生成的Class，我们可以很清楚地看出Collection是以Array的形式呈现的（Artech.SpecialDataContract.Client.OrderManagerService.Order[] orders）：

[System.CodeDom.Compiler.GeneratedCodeAttribute( " System.ServiceModel " , " 3.0.0.0 " )]
[System.ServiceModel.ServiceContractAttribute(ConfigurationName = " OrderManagerService.IOrderManager " )]
public interface IOrderManager {
[System.ServiceModel.OperationContractAttribute(Action="http://tempuri.org/IOrderManager/ProcessWithCollection",ReplyAction="http://tempuri.org/IOrderManager/ProcessWithCollectionResponse")]
voidProcessWithCollection(Artech.SpecialDataContract.Client.OrderManagerService.Order[]orders);
}

因为Array相对很Common的数据类型，基本上所有的厂商均提供了对Array的支持，这也是WCF在通过AddService Reference生成Client端代码的时候，会生成Array的原因。不过并不是我们只有唯一的选择，事实上VS为此提供了扩展，允许我们对于基于Collection 的Data Contract生成我们需要的各种类型，我们只需要在Add Service Reference的时候选择“Configure Service Reference”进行相应的配置：

通过上面的截图，我们发现在Collection Type一项我们有若干选项，我们可以选择我们希望生成的数据类型：Array，ArrayList，LinkedList，Generic List，Collection和BindingList。

Data Contract for Dictionary

前面的内容，我们分别讨论了基于Generic和Collection的Data Contract，接下来，我们来讨论最后一个特殊的数据类型的Data Contract：Dictionary。

延续上面的Order Batch Processing的例子，不过我们现在处理的不是一个OrderCollection对象，而是一个Dictionary对象，线面是Service Contract和Order的定义：

namespace Artech.SpecialDataContract.Contract
{
[ServiceContract]
publicinterfaceIOrderManager
{
[OperationContract(Name="ProcessWithCollection")]
voidProcess(OrderCollectionorders);

[OperationContract(Name="ProcessWithDictionary")]
voidProcess(IDictionary<Guid,Order>orders);
}
}

[DataContract]
public class Order
{
[DataMember]
publicGuidOrderID
{get;set;}

[DataMember]
publicDateTimeOrderDate
{get;set;}
}

闲话少说，我们来看XSD：

<? xmlversion="1.0"encoding="utf-8" ?>
< xs:schema elementFormDefault ="qualified" targetNamespace ="http://schemas.microsoft.com/2003/10/Serialization/Arrays" xmlns:xs ="http://www.w3.org/2001/XMLSchema" xmlns:tns ="http://schemas.microsoft.com/2003/10/Serialization/Arrays" xmlns:ser ="http://schemas.microsoft.com/2003/10/Serialization/" >
< xs:import schemaLocation ="http://artech/Artech.SpecialDataContract/OrderManagerService.svc?xsd=xsd1" namespace ="http://schemas.microsoft.com/2003/10/Serialization/" />
< xs:import schemaLocation ="http://artech/Artech.SpecialDataContract/OrderManagerService.svc?xsd=xsd2" namespace ="http://schemas.datacontract.org/2004/07/Artech.SpecialDataContract.Contract" />
< xs:complexType name ="ArrayOfKeyValueOfguidOrder_SkVQi6O3" >
< xs:annotation >
< xs:appinfo >
< IsDictionary xmlns ="http://schemas.microsoft.com/2003/10/Serialization/" > true </ IsDictionary >
</ xs:appinfo >
</ xs:annotation >
< xs:sequence >
< xs:element minOccurs ="0" maxOccurs ="unbounded" name ="KeyValueOfguidOrder_SkVQi6O3" >
< xs:complexType >
< xs:sequence >
< xs:element name ="Key" type ="ser:guid" />
< xs:element name ="Value" nillable ="true" type ="q1:Order" xmlns:q1 ="http://schemas.datacontract.org/2004/07/Artech.SpecialDataContract.Contract" />
</ xs:sequence >
</ xs:complexType >
</ xs:element >
</ xs:sequence >
</ xs:complexType >
< xs:element name ="ArrayOfKeyValueOfguidOrder_SkVQi6O3" nillable ="true" type ="tns:ArrayOfKeyValueOfguidOrder_SkVQi6O3" />
</ xs:schema >

Data Contract的名称为ArrayOfKeyValueOfguidOrder_SkVQi6O3=ArrayOfKeyValueOf+guid（Key的类型）+Order（Value）+_SkVQi6O3（Hash Value）。从该XSD的结构我们不难看出，只是一个数组，每个元素为Key-Value pair。

我们照例看看通过Add Service Reference方式生成的Client端code中的对应的定义：

[System.CodeDom.Compiler.GeneratedCodeAttribute( " System.ServiceModel " , " 3.0.0.0 " )]
[System.ServiceModel.ServiceContractAttribute(ConfigurationName = " OrderManagerService.IOrderManager " )]
public interface IOrderManager {
[System.ServiceModel.OperationContractAttribute(Action="http://tempuri.org/IOrderManager/ProcessWithDictionary",ReplyAction="http://tempuri.org/IOrderManager/ProcessWithDictionaryResponse")]
voidProcessWithDictionary(System.Collections.Generic.Dictionary<System.Guid,Artech.SpecialDataContract.Client.OrderManagerService.Order>orders);
}

生成的是一个System.Collections.Generic.Dictionary类型。同Collection一样，也依然可以有多种选择：

[原创]谈谈WCF中的Data Contract（1）：Data Contract Overview
[原创]谈谈WCF中的Data Contract（2）：WCF Data Contract对Generic的支持
[原创]谈谈WCF中的Data Contract（3）：WCF Data Contract对Collection & Dictionary的支持
[原创]谈谈WCF中的Data Contract（4）：WCF Data Contract Versioning