使用自定义 WCF 正文反序列化而不更改 URI 模板反序列化 [英] Using Custom WCF Body Deserialization without changing URI Template Deserialization
问题描述
来自这篇博文，我能够创建一个使用 JSON.NET 序列化的自定义 WCF IDispatchMessageFormatter.它工作得很好，但有一个警告:将它与 UriTemplate 一起使用不一定能按预期工作.
From this blog post, I was able to create a custom WCF IDispatchMessageFormatter that uses JSON.NET serialization. It works great with one caveat: using it with UriTemplate doesn't necessarily work as expected.
这是博客文章提供的实现:
Here's the implementation provided by the blog post:
class NewtonsoftJsonDispatchFormatter : IDispatchMessageFormatter
{
private readonly OperationDescription od;
private readonly ServiceEndpoint ep;
private readonly Dictionary<string, int> parameterNames = new Dictionary<string, int>();
public NewtonsoftJsonDispatchFormatter(OperationDescription od, ServiceEndpoint ep, bool isRequest)
{
this.od = od;
this.ep = ep;
if (isRequest)
{
int operationParameterCount = od.Messages[0].Body.Parts.Count;
if (operationParameterCount > 1)
{
this.parameterNames = new Dictionary<string, int>();
for (int i = 0; i < operationParameterCount; i++)
{
this.parameterNames.Add(od.Messages[0].Body.Parts[i].Name, i);
}
}
}
}
public void DeserializeRequest(Message message, object[] parameters)
{
if (message.IsEmpty)
return;
object bodyFormatProperty;
if (!message.Properties.TryGetValue(WebBodyFormatMessageProperty.Name, out bodyFormatProperty) ||
(bodyFormatProperty as WebBodyFormatMessageProperty).Format != WebContentFormat.Raw)
{
throw new InvalidOperationException("Incoming messages must have a body format of Raw. Is a ContentTypeMapper set on the WebHttpBinding?");
}
XmlDictionaryReader bodyReader = message.GetReaderAtBodyContents();
bodyReader.ReadStartElement("Binary");
byte[] rawBody = bodyReader.ReadContentAsBase64();
using (MemoryStream ms = new MemoryStream(rawBody))
using (StreamReader sr = new StreamReader(ms))
{
if (parameters.Length == 1)
parameters[0] = Helper.serializer.Deserialize(sr, od.Messages[0].Body.Parts[0].Type);
else
{
// multiple parameter, needs to be wrapped
using (Newtonsoft.Json.JsonReader reader = new Newtonsoft.Json.JsonTextReader(sr))
{
reader.Read();
if (reader.TokenType != Newtonsoft.Json.JsonToken.StartObject)
throw new InvalidOperationException("Input needs to be wrapped in an object");
reader.Read();
while (reader.TokenType == Newtonsoft.Json.JsonToken.PropertyName)
{
string parameterName = reader.Value as string;
reader.Read();
if (this.parameterNames.ContainsKey(parameterName))
{
int parameterIndex = this.parameterNames[parameterName];
parameters[parameterIndex] = Helper.serializer.Deserialize(reader, this.od.Messages[0].Body.Parts[parameterIndex].Type);
}
else
reader.Skip();
reader.Read();
}
}
}
}
}
public Message SerializeReply(MessageVersion messageVersion, object[] parameters, object result) { ... }
}
基本上，DeserializeMethod签名中的object[]参数就是这个方法需要实例化的out参数.
Basically, the object[] parameters in the DeserializeMethod signature are out parameters that this method needs to instantiate.
因此，这对于处理这样的 REST 端点非常有用:
So, this does a great job to handle a REST endpoint like this:
[WebInvoke(Method="POST", UriTemplate="foo/")]
public Foo MakeFoo(Foo foo) { ... }
或者像这样:
[WebInvoke(Method="POST", UriTemplate="FooBar/")]
public FooBar FooBar(Foo foo, Bar bar) { .. }
但它目前没有将 URI 模板参数映射到方法参数，例如像这样:
but it currently doesn't map the URI template parameters to the method parameters, e.g. something like this:
[WebGet(UriTemplate="Foo/{id}")]
public Foo GetFoo(string id) { ... }
Microsoft 写在重写的 GetRequestDispatchFormatter:
Microsoft writes on the overriden GetRequestDispatchFormatter:
这是一个扩展点，派生行为可以使用它来提供自己的 IDispatchMessageFormatter 实现，该实现被调用以从请求消息中反序列化服务操作的输入参数.服务操作的 UriTemplate 中指定的参数必须从请求消息的 To URI 中反序列化，其他参数必须从请求消息的正文中反序列化.
This is an extensibility point that derived behaviors can use to supply their own implementation of IDispatchMessageFormatter that is called to deserialize the input parameters of the service operation from the request message. Parameters specified in the UriTemplate of the service operation must be deserialized from the To URI of the request message and other parameters must be deserialized from the body of the request message.
所以，太好了.我更新了消息正文中参数的反序列化.但我不想覆盖 UriTemplate 中的参数反序列化.有没有办法使用现有代码将传入的 URI 请求映射到参数，并使用 UriTemplate 的默认处理方式?
So, great. I updated the deserialization of the parameters from the body of a message. But I don't want to override deserializing the parameters in the UriTemplate. Is there any way to use existing code to map the incoming URI request to the parameters with the default way UriTemplate is handled?
看来我需要使用类似 UriTemplateDispatchFormatter 但我不确定如何实现它，而且它是非公开的.
It seems I need to use something like the UriTemplateDispatchFormatter but I'm not sure how to implement this, and it's non-public.
推荐答案
好吧，这可能是我不得不做的最可笑的事情，但是复制 UriTemplateDispatchFormatter 的源代码，你可以只需返回一个 UriTemplateDispatchFormatter 和一个内部"IDispatchFormatter，它对应于我在此处提供的 IDispatchFormatter.不知道为什么这个类是内部的>_>
Well, this is maybe the most ridiculous thing I've had to do, but copying the source code for UriTemplateDispatchFormatter, you can simply return a UriTemplateDispatchFormatter with an "inner" IDispatchFormatter that corresponds to the IDispatchFormatter I provided here. Not sure why this class was made internal >_>
以下类定义:
class UriTemplateDispatchFormatter : IDispatchMessageFormatter
{
internal Dictionary<int, string> pathMapping;
internal Dictionary<int, KeyValuePair<string, Type>> queryMapping;
Uri baseAddress;
IDispatchMessageFormatter bodyFormatter;
string operationName;
QueryStringConverter qsc;
int totalNumUTVars;
UriTemplate uriTemplate;
public UriTemplateDispatchFormatter(OperationDescription operationDescription, IDispatchMessageFormatter bodyFormatter, QueryStringConverter qsc, string contractName, Uri baseAddress)
{
this.bodyFormatter = bodyFormatter;
this.qsc = qsc;
this.baseAddress = baseAddress;
this.operationName = operationDescription.Name;
Populate(
out this.pathMapping,
out this.queryMapping,
out this.totalNumUTVars,
out this.uriTemplate,
operationDescription,
qsc,
contractName);
}
public void DeserializeRequest(Message message, object[] parameters)
{
object[] bodyParameters = new object[parameters.Length - this.totalNumUTVars];
if (bodyParameters.Length != 0)
{
this.bodyFormatter.DeserializeRequest(message, bodyParameters);
}
int j = 0;
UriTemplateMatch utmr = null;
string UTMRName = "UriTemplateMatchResults";
if (message.Properties.ContainsKey(UTMRName))
{
utmr = message.Properties[UTMRName] as UriTemplateMatch;
}
else
{
if (message.Headers.To != null && message.Headers.To.IsAbsoluteUri)
{
utmr = this.uriTemplate.Match(this.baseAddress, message.Headers.To);
}
}
NameValueCollection nvc = (utmr == null) ? new NameValueCollection() : utmr.BoundVariables;
for (int i = 0; i < parameters.Length; ++i)
{
if (this.pathMapping.ContainsKey(i) && utmr != null)
{
parameters[i] = nvc[this.pathMapping[i]];
}
else if (this.queryMapping.ContainsKey(i) && utmr != null)
{
string queryVal = nvc[this.queryMapping[i].Key];
parameters[i] = this.qsc.ConvertStringToValue(queryVal, this.queryMapping[i].Value);
}
else
{
parameters[i] = bodyParameters[j];
++j;
}
}
}
public Message SerializeReply(MessageVersion messageVersion, object[] parameters, object result)
{
throw new NotImplementedException();
}
private static void Populate(out Dictionary<int, string> pathMapping,
out Dictionary<int, KeyValuePair<string, Type>> queryMapping,
out int totalNumUTVars,
out UriTemplate uriTemplate,
OperationDescription operationDescription,
QueryStringConverter qsc,
string contractName)
{
pathMapping = new Dictionary<int, string>();
queryMapping = new Dictionary<int, KeyValuePair<string, Type>>();
string utString = GetUTStringOrDefault(operationDescription);
uriTemplate = new UriTemplate(utString);
List<string> neededPathVars = new List<string>(uriTemplate.PathSegmentVariableNames);
List<string> neededQueryVars = new List<string>(uriTemplate.QueryValueVariableNames);
Dictionary<string, byte> alreadyGotVars = new Dictionary<string, byte>(StringComparer.OrdinalIgnoreCase);
totalNumUTVars = neededPathVars.Count + neededQueryVars.Count;
for (int i = 0; i < operationDescription.Messages[0].Body.Parts.Count; ++i)
{
MessagePartDescription mpd = operationDescription.Messages[0].Body.Parts[i];
string parameterName = XmlConvert.DecodeName(mpd.Name);
if (alreadyGotVars.ContainsKey(parameterName))
{
throw new InvalidOperationException();
}
List<string> neededPathCopy = new List<string>(neededPathVars);
foreach (string pathVar in neededPathCopy)
{
if (string.Compare(parameterName, pathVar, StringComparison.OrdinalIgnoreCase) == 0)
{
if (mpd.Type != typeof(string))
{
throw new InvalidOperationException();
}
pathMapping.Add(i, parameterName);
alreadyGotVars.Add(parameterName, 0);
neededPathVars.Remove(pathVar);
}
}
List<string> neededQueryCopy = new List<string>(neededQueryVars);
foreach (string queryVar in neededQueryCopy)
{
if (string.Compare(parameterName, queryVar, StringComparison.OrdinalIgnoreCase) == 0)
{
if (!qsc.CanConvert(mpd.Type))
{
throw new InvalidOperationException();
}
queryMapping.Add(i, new KeyValuePair<string, Type>(parameterName, mpd.Type));
alreadyGotVars.Add(parameterName, 0);
neededQueryVars.Remove(queryVar);
}
}
}
if (neededPathVars.Count != 0)
{
throw new InvalidOperationException();
}
if (neededQueryVars.Count != 0)
{
throw new InvalidOperationException();
}
}
private static string GetUTStringOrDefault(OperationDescription operationDescription)
{
string utString = GetWebUriTemplate(operationDescription);
if (utString == null && GetWebMethod(operationDescription) == "GET")
{
utString = MakeDefaultGetUTString(operationDescription);
}
if (utString == null)
{
utString = operationDescription.Name;
}
return utString;
}
private static string MakeDefaultGetUTString(OperationDescription od)
{
StringBuilder sb = new StringBuilder(XmlConvert.DecodeName(od.Name));
//sb.Append("/*"); // note: not + "/*", see 8988 and 9653
if (!IsUntypedMessage(od.Messages[0]))
{
sb.Append("?");
foreach (MessagePartDescription mpd in od.Messages[0].Body.Parts)
{
string parameterName = XmlConvert.DecodeName(mpd.Name);
sb.Append(parameterName);
sb.Append("={");
sb.Append(parameterName);
sb.Append("}&");
}
sb.Remove(sb.Length - 1, 1);
}
return sb.ToString();
}
private static bool IsUntypedMessage(MessageDescription message)
{
if (message == null)
{
return false;
}
return (message.Body.ReturnValue != null && message.Body.Parts.Count == 0 && message.Body.ReturnValue.Type == typeof(Message)) ||
(message.Body.ReturnValue == null && message.Body.Parts.Count == 1 && message.Body.Parts[0].Type == typeof(Message));
}
private static void EnsureOk(WebGetAttribute wga, WebInvokeAttribute wia, OperationDescription od)
{
if (wga != null && wia != null)
{
throw new InvalidOperationException();
}
}
private static string GetWebUriTemplate(OperationDescription od)
{
// return exactly what is on the attribute
WebGetAttribute wga = od.Behaviors.Find<WebGetAttribute>();
WebInvokeAttribute wia = od.Behaviors.Find<WebInvokeAttribute>();
EnsureOk(wga, wia, od);
if (wga != null)
{
return wga.UriTemplate;
}
else if (wia != null)
{
return wia.UriTemplate;
}
else
{
return null;
}
}
private static string GetWebMethod(OperationDescription od)
{
WebGetAttribute wga = od.Behaviors.Find<WebGetAttribute>();
WebInvokeAttribute wia = od.Behaviors.Find<WebInvokeAttribute>();
EnsureOk(wga, wia, od);
if (wga != null)
{
return "GET";
}
else if (wia != null)
{
return wia.Method ?? "POST";
}
else
{
return "POST";
}
}
}
以及以下行为:
class NewtonsoftJsonBehavior : WebHttpBehavior
{
protected override IDispatchMessageFormatter GetRequestDispatchFormatter(OperationDescription operationDescription, ServiceEndpoint endpoint)
{
return new UriTemplateDispatchFormatter(
operationDescription,
new NewtonsoftJsonDispatchFormatter(operationDescription, endpoint, true),
GetQueryStringConverter(operationDescription),
endpoint.Contract.Name,
endpoint.Address.Uri);
}
protected override IDispatchMessageFormatter GetReplyDispatchFormatter(OperationDescription od, ServiceEndpoint ep)
{
return new NewtonsoftJsonDispatchFormatter(od, ep, false);
}
}
作品
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