WCF中的复合类型错误

Question

WCF新手寻求帮助。我在做什么错在这里： ICardService

[ServiceContract(Namespace = "http://xxxx.xxxxxx.xxxx/xx/xxxxxx")] 
interface ICardService 
{ 
    [OperationContract] 
    Coupon CreateCouponCard(string cardDefinitionCode); 
} 

---

public class CardService : ICardService 
    { 
     public Coupon CreateCouponCard(string cardDefinitionCode) 
     { 
      Coupon composite = new Coupon(); 

      if (composite == null) 
      { 
       throw new ArgumentNullException("composite"); 
      } 
      if (composite.BoolValue) 
      { 
       composite.PassTypeIdentifier="sdfsdf"; 
       composite.Icon.DisplayGroup = "czxczxczx"; 
      } 
      return composite; 
     } 
    } 

---

[DataContract(Namespace = "")] 
    public class Coupon : CardCommonDefinition 
     { 
      [DataMember] 
      public string Description {get; set;} 

[DataMember] 
public bool BoolValue 
     { 
      get { return boolValue; } 
      set { boolValue = value; } 
     } 

} 

---

[DataContract(Namespace = "")] 
    public class CardCommonDefinition 
    { 
     [DataMember] 
     public string PassTypeIdentifier {get; set;} 
    [DataMember] 
     public CardFieldDefinitionEntity Icon {get; set;} 
    } 

---

[DataContract(Namespace = "")] 
    public class CardFieldDefinitionEntity 
    { 

     [DataMember] 
     public string DisplayGroup {get; set;} 
} 

---

当我运行它时，它在composite.Icon.DisplayGroup =“czxczxczx”;失败。对象未设置为对象的实例。

我没有任何线索来解决它，你能帮我吗？

Answer 1

你可以通过两种方式解决这个问题。

One-Initialize Icon property before using it。

public Coupon CreateCouponCard(string cardDefinitionCode) 
{ 

    Coupon composite = new Coupon(); 
    if (composite == null) 
    { 
     throw new ArgumentNullException("composite"); 
    } 
    if (composite.BoolValue) 
    { 
     composite.PassTypeIdentifier="sdfsdf"; 
     composite.Icon = new CardFieldDefinitionEntity(); 
     composite.Icon.DisplayGroup = "czxczxczx"; 
    } 
    return composite; 
} 

两个 - 有CardCommonDefinition构造和它初始化Icon属性，使你不必担心它被空。

[DataContract(Namespace = "")] 
public class CardCommonDefinition 
{ 
    public CardCommonDefinition() 
    { 
     this.Icon = new CardFieldDefinitionEntity(); 
    } 
    [DataMember] 
    public string PassTypeIdentifier {get; set;} 
    [DataMember] 
    public CardFieldDefinitionEntity Icon {get; set;} 
} 

[DataContract(Namespace = "")] 
public class Coupon : CardCommonDefinition 
{ 
    public Coupon : base() 
    { } 
    [DataMember] 
    public string Description {get; set;} 
    [DataMember] 
    public bool BoolValue 
    { 
     get { return boolValue; } 
     set { boolValue = value; } 
    } 
}