SignalR 2.0.0 beta2 IJsonSerializer 可扩展性

Question

我想添加一些自定义序列化逻辑，以便转换后的 json 包含驼峰式属性。

出于这个原因，我尝试用我在此链接中找到的 IJsonSerializer 替换默认的 IJsonSerializer：

https://github.com/SignalR/SignalR/issues/500

但是似乎有问题。更具体地说，JsonNetSerializer 和 IJsonSerializer 类不存在于任何 signalR 程序集中。在这方面，最新版本的 signalR 是否发生了任何变化？

Answer 1

只是为了澄清一点，从 SignalR 2 开始，您不能将序列化程序替换为不是来自 JSON.NET 的序列化程序。但是，SinglR 使用的 JSON.NET 序列化程序可以使用 DependacyResolver 创建和设置。

这是一个创建新 JsonSerializer 来处理引用循环的示例：

  protected void Application_Start()
  {
     var serializerSettings = new JsonSerializerSettings();
     serializerSettings.ReferenceLoopHandling = ReferenceLoopHandling.Serialize;
     serializerSettings.PreserveReferencesHandling = PreserveReferencesHandling.Objects;

     var serializer = JsonSerializer.Create(serializerSettings);
     GlobalHost.DependencyResolver.Register(typeof(JsonSerializer), () => serializer); 
  }

Answer 2

在 SignalR 2.0 中，您无法替换 JsonSerializer，不再有 IJsonSerializer 抽象。它总是 JSON.NET。

Answer 3

这是一个使用 StructureMap 覆盖 SignalR 依赖解析器的示例。 在这个特定示例中，我将转换为 camelCase 属性并将枚举转换为字符串。

在启动期间：

Microsoft.AspNet.SignalR.GlobalHost.DependencyResolver = new StructureMapSignalRDependencyResolver();

课程如下：

public class StructureMapSignalRDependencyResolver : Microsoft.AspNet.SignalR.DefaultDependencyResolver
{
    public override object GetService(Type serviceType)
    {
        object service;
        if (!serviceType.IsAbstract && !serviceType.IsInterface && serviceType.IsClass)
        {
            // Concrete type resolution
            service = StructureMap.ObjectFactory.GetInstance(serviceType);
        }
        else
        {
            // Other type resolution with base fallback
            service = StructureMap.ObjectFactory.TryGetInstance(serviceType) ?? base.GetService(serviceType);
        }

        return service;
    }

    public override IEnumerable<object> GetServices(Type serviceType)
    {
        var objects = StructureMap.ObjectFactory.GetAllInstances(serviceType).Cast<object>();
        return objects.Concat(base.GetServices(serviceType));
    }
}

StructureMap 的设置是：

ObjectFactory.Configure(c =>
    {
        c.Scan(a =>
            {
                // scan the assembly that SignalR is referenced by
                a.AssemblyContainingType<AppHost>(); 
                a.WithDefaultConventions();
            });

        c.For<Newtonsoft.Json.JsonSerializer>()
         .Singleton()
         .Use(new Newtonsoft.Json.JsonSerializer 
             { 
                 ContractResolver = new SignalRContractResolver(), 
                 Converters = { new Newtonsoft.Json.Converters.StringEnumConverter() } 
             });
    });

这是合同解析器：

public class SignalRContractResolver : Newtonsoft.Json.Serialization.IContractResolver
{
    private readonly Assembly _assembly;
    private readonly Newtonsoft.Json.Serialization.IContractResolver _camelCaseContractResolver;
    private readonly Newtonsoft.Json.Serialization.IContractResolver _defaultContractSerializer;

    public SignalRContractResolver()
    {
        _defaultContractSerializer = new Newtonsoft.Json.Serialization.DefaultContractResolver();
        _camelCaseContractResolver = new Newtonsoft.Json.Serialization.CamelCasePropertyNamesContractResolver();
        _assembly = typeof(Connection).Assembly;
    }

    public Newtonsoft.Json.Serialization.JsonContract ResolveContract(Type type)
    {
        if (type.Assembly.Equals(_assembly))
        {
            return _defaultContractSerializer.ResolveContract(type);
        }

        return _camelCaseContractResolver.ResolveContract(type);
    }
}