Activer le Service de Données WCF pour accepter/retour JSON par défaut

Afin de permettre json via le format $balise comme ceci:

host:8038/YourService.svc/?$format=json

Ajouter cet attribut à votre déclaration de service:

[JSONPSupportBehavior]
public class Service : DataService<YourEntities>

Ajouter une classe à votre service:

using System;
using System.ServiceModel;
using System.ServiceModel.Channels;
using System.ServiceModel.Description;
using System.ServiceModel.Dispatcher;
using System.Text;
using System.Xml;
namespace YourNamespaceHere.Service
{
public class JSONPSupportInspector : IDispatchMessageInspector
{
//Assume utf-8, note that Data Services supports
//charset negotation, so this needs to be more
//sophisticated (and per-request) if clients will 
//use multiple charsets
private static Encoding encoding = Encoding.UTF8;
#region IDispatchMessageInspector Members
public object AfterReceiveRequest(ref System.ServiceModel.Channels.Message request, IClientChannel channel, InstanceContext instanceContext)
{
if (request.Properties.ContainsKey("UriTemplateMatchResults"))
{
HttpRequestMessageProperty httpmsg = (HttpRequestMessageProperty)request.Properties[HttpRequestMessageProperty.Name];
UriTemplateMatch match = (UriTemplateMatch)request.Properties["UriTemplateMatchResults"];
string format = match.QueryParameters["$format"];
if ("json".Equals(format, StringComparison.InvariantCultureIgnoreCase))
{
//strip out $format from the query options to avoid an error
//due to use of a reserved option (starts with "$")
match.QueryParameters.Remove("$format");
//replace the Accept header so that the Data Services runtime 
//assumes the client asked for a JSON representation
httpmsg.Headers["Accept"] = "application/json";
string callback = match.QueryParameters["$callback"];
if (!string.IsNullOrEmpty(callback))
{
match.QueryParameters.Remove("$callback");
return callback;
}
}
}
return null;
}
public void BeforeSendReply(ref System.ServiceModel.Channels.Message reply, object correlationState)
{
if (correlationState != null && correlationState is string)
{
//if we have a JSONP callback then buffer the response, wrap it with the
//callback call and then re-create the response message
string callback = (string)correlationState;
XmlDictionaryReader reader = reply.GetReaderAtBodyContents();
reader.ReadStartElement();
string content = JSONPSupportInspector.encoding.GetString(reader.ReadContentAsBase64());
content = callback + "(" + content + ")";
Message newreply = Message.CreateMessage(MessageVersion.None, "", new Writer(content));
newreply.Properties.CopyProperties(reply.Properties);
reply = newreply;
}
}
#endregion
class Writer : BodyWriter
{
private string content;
public Writer(string content)
: base(false)
{
this.content = content;
}
protected override void OnWriteBodyContents(XmlDictionaryWriter writer)
{
writer.WriteStartElement("Binary");
byte[] buffer = JSONPSupportInspector.encoding.GetBytes(this.content);
writer.WriteBase64(buffer, 0, buffer.Length);
writer.WriteEndElement();
}
}
}
//Simply apply this attribute to a DataService-derived class to get
//JSONP support in that service
[AttributeUsage(AttributeTargets.Class)]
public class JSONPSupportBehaviorAttribute : Attribute, IServiceBehavior
{
#region IServiceBehavior Members
void IServiceBehavior.AddBindingParameters(ServiceDescription serviceDescription, ServiceHostBase serviceHostBase, System.Collections.ObjectModel.Collection<ServiceEndpoint> endpoints, System.ServiceModel.Channels.BindingParameterCollection bindingParameters)
{
}
void IServiceBehavior.ApplyDispatchBehavior(ServiceDescription serviceDescription, ServiceHostBase serviceHostBase)
{
foreach (ChannelDispatcher cd in serviceHostBase.ChannelDispatchers)
{
foreach (EndpointDispatcher ed in cd.Endpoints)
{
ed.DispatchRuntime.MessageInspectors.Add(new JSONPSupportInspector());
}
}
}
void IServiceBehavior.Validate(ServiceDescription serviceDescription, ServiceHostBase serviceHostBase)
{
}
#endregion
}
}

OriginalL'auteur George