问题描述
限时送ChatGPT账号..我正在尝试通过 WCF 传递一个具有 Dictionary 属性的类,它对一种方法失败,但对另一种方法有效.当该类在 List
内返回时,它会起作用.但是当在 DataTable
中返回该类时,客户端只是说连接已断开并且没有出现错误.
这是导致问题的类:
[数据契约]公共类 DetailLog{[数据成员]公共字符串名称{得到;放;}[数据成员]公共字符串 SubAction{得到;放;}[数据成员]公共字典<字符串,字符串>字段{得到;放;}[数据成员]公共字符串用户名{得到;放;}}
我开始创建一个没有问题的方法:
public ListGetDetailLog(List IDs, List actionTypeIds, List userIds, DateTime beginDate, DateTime endDate)
然后我们需要创建一些非常动态的报告,所以我使用了我们以前用于其他动态报告的 DataTable.
但我需要传递 DetailLog 类,所以我创建了一个该类型的 DataTable 列:
public DataTable GetCustomDetailReport(int CustomReportID, List reportFilters){数据表数据 = 新数据表();...data.Columns.Add("DetailLog", typeof(DetailLog));...}
此方法会在 WCF 主机端正常退出,但客户端会出现连接丢失的错误.我尝试在界面中为 OperationContract 添加 ServiceKnownType 但它没有修复它:
[操作契约][ServiceKnownType(typeof(DetailLog))]DataTable GetCustomUserAuditReport(int CustomReportID, List reportFilters);
当该方法返回 DataTable 时,我无法真正调试序列化,因此我将此代码添加到 GetCustomDetailReport() 的末尾以捕获错误.
DataContractSerializer ser = new DataContractSerializer(typeof(DataTable), new List { typeof(DetailLog) });ser.WriteObject(Stream.Null, 数据);
当我这样做时,我看到了一个例外
<块引用>无法序列化 System.Collections.Generic.Dictionary`2 类型的成员 ...,因为它实现了 IDictionary.
解决方案您的问题如下:
Dictionary
由 数据协定序列化程序 在 WCF 中使用,如 文档.这就是为什么您的 DetailLog
类可以通过 WCF 作为根对象成功通过网络发送.
此序列化程序还支持 IXmlSerializable
允许类型将自己手动序列化为 XML.
DataTable
实现了 IXmlSerializable
.
在内部,DataTable
使用序列化非原始条目.serialization.xmlserializer%28v=vs.110%29.aspx" rel="nofollow">XmlSerializer
-- 一个完全不同的序列化器,使用完全不同的代码库.
XmlSerializer
不支持字典.因此,当嵌套在 DataTable
中时,您的 DetailLog
无法通过 WCF 通过网络发送.
作为一个无关的问题,你还需要设置数据表名,如果不设置,序列化会抛出异常:
data.TableName = "CustomDetailReport";//例如
要解决字典的问题,您需要使 DetailLog
类可被两个序列化器序列化.问题 如何序列化/反序列化为Dictionary
来自不使用 XElement 的自定义 XML? 提供了多种方法来序列化其字典属性,包括使用代理数组属性:
[XmlType("KeyValue"), XmlRoot("KeyValue")]公共类 SerializableKeyValuePair{公共 TKey 密钥 { 获取;放;}公共 TValue 值 { 获取;放;}}公共静态类 SerializableKeyValuePairExtensions{公共静态 SerializableKeyValuePairToSerializablePair(这个 KeyValuePair 对){返回新的 SerializableKeyValuePair{ Key = pair.Key, Value = pair.Value };}}[数据合约]公共类 DetailLog{[数据成员]公共字符串名称{获取;放;}[数据成员]公共字符串 SubAction { 获取;放;}[数据成员][XmlIgnore]公共字典<字符串,字符串>字段{获取;放;}[忽略数据成员][XmlArray("字段")][Browsable(false), EditorBrowsable(EditorBrowsableState.Never), DebuggerBrowsable(DebuggerBrowsableState.Never)]public SerializableKeyValuePair[] FieldsArray{得到{返回字段 == null ?null : Fields.Select(p => p.ToSerializablePair()).ToArray();}放{字段 = 值 == 空?null : value.ToDictionary(p => p.Key, p => p.Value);}}[数据成员]公共字符串用户名 { 获取;放;}}
WCF 现在应该能够通过网络成功发送您的 DataTable
.
I am trying to pass a class with a Dictionary property over WCF and it is failing for one method but works for another. When the class is returned inside a List
, it works. But when the class is returned inside a DataTable
, the client just says the connection was disconnected and no error shows up.
Here is the class causing issues:
[DataContract]
public class DetailLog
{
[DataMember]
public string Name
{
get;
set;
}
[DataMember]
public string SubAction
{
get;
set;
}
[DataMember]
public Dictionary<string, string> Fields
{
get;
set;
}
[DataMember]
public string UserName
{
get;
set;
}
}
I started out creating a method that works without issue:
public List<DetailLog> GetDetailLog(List<int> IDs, List<int> actionTypeIds, List<int> userIds, DateTime beginDate, DateTime endDate)
Then we needed to create some very dynamic reports so I used a DataTable which we have used previously for other dynamic reports.
But I needed to pass along the DetailLog class so I created a DataTable column of that type:
public DataTable GetCustomDetailReport(int CustomReportID, List<CustomReportFilter> reportFilters)
{
DataTable data = new DataTable();
...
data.Columns.Add("DetailLog", typeof(DetailLog));
...
}
This method would would exit fine on the WCF host side but the client side would error about the connection being lost. I tried adding ServiceKnownType for the OperationContract in the interface but it did not fix it:
[OperationContract]
[ServiceKnownType(typeof(DetailLog))]
DataTable GetCustomUserAuditReport(int CustomReportID, List<CustomReportFilter> reportFilters);
I cannot really debug the serialization when the method returns the DataTable so I added this code to the end of the GetCustomDetailReport() to catch the error.
DataContractSerializer ser = new DataContractSerializer(typeof(DataTable), new List<Type> { typeof(DetailLog) });
ser.WriteObject(Stream.Null, data);
When I did, I saw an exception
Cannot serialize member ... of type System.Collections.Generic.Dictionary`2 because it implements IDictionary.
解决方案
Your issue is as follows:
Dictionary<TKey, TValue>
is supported by the data contract serializer used in WCF, as explained in the docs. This is why your DetailLog
class can be sent over the wire successfully by WCF as a root object.
This serializer also supports IXmlSerializable
to allow types to manually serialize themselves to XML.
DataTable
implements IXmlSerializable
.
Internally, DataTable
serializes non-primitive entries using XmlSerializer
-- a completely different serializer that uses a completely different code base.
XmlSerializer
does not support dictionaries. Thus your DetailLog
cannot be sent over the wire by WCF when nested in a DataTable
.
As an unrelated problem, you also need to set the data table name, serialization will throw an exception if you do not:
data.TableName = "CustomDetailReport"; // For instance
To work around the issue with dictionaries, you need to make your DetailLog
class serializable by both serializers. The question How to serialize/deserialize to Dictionary<int, string>
from custom XML not using XElement? gives a variety of ways to serialize its dictionary property, including using a proxy array property:
[XmlType("KeyValue"), XmlRoot("KeyValue")]
public class SerializableKeyValuePair<TKey, TValue>
{
public TKey Key { get; set; }
public TValue Value { get; set; }
}
public static class SerializableKeyValuePairExtensions
{
public static SerializableKeyValuePair<TKey, TValue> ToSerializablePair<TKey, TValue>(this KeyValuePair<TKey, TValue> pair)
{
return new SerializableKeyValuePair<TKey, TValue> { Key = pair.Key, Value = pair.Value };
}
}
[DataContract]
public class DetailLog
{
[DataMember]
public string Name { get; set; }
[DataMember]
public string SubAction { get; set; }
[DataMember]
[XmlIgnore]
public Dictionary<string, string> Fields { get; set; }
[IgnoreDataMember]
[XmlArray("Fields")]
[Browsable(false), EditorBrowsable(EditorBrowsableState.Never), DebuggerBrowsable(DebuggerBrowsableState.Never)]
public SerializableKeyValuePair<string, string>[] FieldsArray
{
get
{
return Fields == null ? null : Fields.Select(p => p.ToSerializablePair()).ToArray();
}
set
{
Fields = value == null ? null : value.ToDictionary(p => p.Key, p => p.Value);
}
}
[DataMember]
public string UserName { get; set; }
}
WCF should now be able to send your DataTable
over the wire successfully.
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