Odata Webapi - 如何在 7.0 核心中注入 ODataResourceDeserializer？

Question

文档非常少，我尝试过的所有结果都注入了反序列化程序，但正常的 odata url 不再起作用了。

https://github.com/OData/WebApi/issues/158 有针对 5.6 的解决方案。

最后的相关评论是：

@dbenzhuser - 在该提交中，查看 ODataFormatterTests.cs 以了解如何 注入自定义反序列化器/反序列化器提供程序。你仍然可以使用 一个自定义的 DeserializerProvider 但它是通过 DI 而不是 通过 ODataMediaTypeFormatters 注入。

这是毫无意义的。我在那里尝试了代码，但正如我所说，它破坏了 URL。

现在我的 Odata 设置很简单：

    services.AddMvc()
        .SetCompatibilityVersion(CompatibilityVersion.Version_2_1);
    services.AddOData();

\UnitTest\Microsoft.AspNet.OData.Test.Shared\Formatter\ODataFormatterTests.cs

有注入它们的示例（如第 379-383 行）

        config.MapODataServiceRoute("IgnoredRouteName", null, builder =>
            builder.AddService(Microsoft.OData.ServiceLifetime.Singleton, sp => ODataTestUtil.GetEdmModel())
                .AddService<ODataSerializerProvider>(ServiceLifetime.Singleton, sp => new CustomSerializerProvider())
                .AddService<IEnumerable<IODataRoutingConvention>>(ServiceLifetime.Singleton, sp =>
                    ODataRoutingConventions.CreateDefaultWithAttributeRouting("IgnoredRouteName", config)));

但如果不删除核心 odata 路由，我似乎无法正常工作。

有人知道如何在不破坏基本功能的情况下将其用于当前版本吗？

Answer 1

如果要维护基本功能，分为三个步骤：

1. 您的 DeserializerProvider 实现应该默认为您的自定义 Deserializer 无法管理的所有场景的基本实现。在以下示例中，自定义反序列化器仅对资源而不是集合进行操作：

   public class EntityTypeDeserializerProvider : DefaultODataDeserializerProvider
   {
       private readonly DataContractDeserializer _dataContractDeserializer;
       public EntityTypeDeserializerProvider(IServiceProvider rootContainer)
           : base(rootContainer)
       {
           _dataContractDeserializer = new DataContractDeserializer(this);
       }
   
       public override ODataEdmTypeDeserializer GetEdmTypeDeserializer(IEdmTypeReference edmType)
       {
           if(edmType.Definition.TypeKind == EdmTypeKind.Complex || edmType.Definition.TypeKind == EdmTypeKind.Entity)
               return _dataContractDeserializer;
           else 
               return base.GetEdmTypeDeserializer(edmType);
       }
   }
   

2. 与 provider 一样，您的自定义 _Deserializer 应该调用您不需要自定义的所有内容的基本实现。在以下实现中，我们仅尝试强制执行反序列化的属性的顺序以及调用 DataContract OnDeserializing 和 OnDeserialized 方法，其余的反序列化不受影响：

   /// <summary>
   /// OData serializer that oberys the DataMember Order Attribute and OnDeserializing and OnDeserialized attributes on the resource definition
   /// </summary>
   public class DataContractDeserializer : ODataResourceDeserializer
   {
       public DataContractDeserializer(ODataDeserializerProvider provider)
           : base(provider) { }
   
       public override object CreateResourceInstance(IEdmStructuredTypeReference structuredType, ODataDeserializerContext readContext)
       {
           var resource = base.CreateResourceInstance(structuredType, readContext);
           var type = resource.GetType();
           if(type.GetCustomAttributesData().Any(x => x.AttributeType == typeof(DataContractAttribute)))
           {
               // manually call OnDeserializing
               var init = type.GetMethods(System.Reflection.BindingFlags.Instance | System.Reflection.BindingFlags.Public | System.Reflection.BindingFlags.NonPublic).FirstOrDefault(x => x.GetCustomAttributesData().Any(a => a.AttributeType == typeof(OnDeserializingAttribute)));
               if(init != null)
               {
                   init.Invoke(resource, new object[] { new StreamingContext(StreamingContextStates.Remoting, readContext ) });
               }
           }
           return resource;
       }
   
       public override object ReadResource(ODataResourceWrapper resourceWrapper, IEdmStructuredTypeReference structuredType, ODataDeserializerContext readContext)
       {
           var resource = base.ReadResource(resourceWrapper, structuredType, readContext);
           var type = resource.GetType();
           if (type.GetCustomAttributesData().Any(x => x.AttributeType == typeof(DataContractAttribute)))
           {
               // manually call OnDeserialized
               var final = type.GetMethods(System.Reflection.BindingFlags.Instance | System.Reflection.BindingFlags.Public | System.Reflection.BindingFlags.NonPublic).FirstOrDefault(x => x.GetCustomAttributesData().Any(a => a.AttributeType == typeof(OnDeserializedAttribute)));
               if (final != null)
               {
                   final.Invoke(resource, new object[] { new StreamingContext(StreamingContextStates.Remoting, readContext) });
               }
           }
           return resource;
       }
       public override void ApplyStructuralProperties(object resource, ODataResourceWrapper resourceWrapper, IEdmStructuredTypeReference structuredType, ODataDeserializerContext readContext)
       {
           var type = resource.GetType();
           var memberDescriptors = type.GetProperties().Where(x => x.HasAttribute<DataMemberAttribute>());
           if (memberDescriptors.Any())
           {
               var orderedProperties = from p in resourceWrapper.Resource.Properties
                                       let clsProperty = memberDescriptors.FirstOrDefault(m => m.Name == p.Name)
                                       let memberAtt = (DataMemberAttribute)(clsProperty?.GetCustomAttributes(true).FirstOrDefault(a => a.GetType() == typeof(DataMemberAttribute)))
                                       orderby (memberAtt?.Order).GetValueOrDefault()
                                       select p;
               foreach (var property in orderedProperties)
               {
                   ApplyStructuralProperty(resource, property, structuredType, readContext);
               }
           }
           else
               base.ApplyStructuralProperties(resource, resourceWrapper, structuredType, readContext);
       }
   }
   

3. 最后，你需要用你自己的替换默认的DeserializerProvider注册，下面是一个重载到MapODataServiceRoute的例子，它注册了之前的DeserializerProvider 2 个示例。
   我已经注释掉了一个注册特定 SerializerProvider 的示例

   private static ODataRoute MapODataServiceRoute(this HttpConfiguration configuration, string routeName,
       string routePrefix, IEdmModel model, ODataBatchHandler batchHandler = null, ODataUriResolver uriResolver = null, IList<IODataRoutingConvention> routingConventions = null)
   {
        return configuration.MapODataServiceRoute(routeName, routePrefix, builder =>
            builder
                .AddService(ServiceLifetime.Singleton, sp => model)
                //.AddService<ODataSerializerProvider>(ServiceLifetime.Singleton, sp => new DefaultODataSerializerProvider(sp))
                .AddService<ODataDeserializerProvider>(ServiceLifetime.Singleton, sp => new EntityTypeDeserializerProvider(sp))
                .AddService(ServiceLifetime.Singleton, sp => batchHandler ?? new DefaultODataBatchHandler(GlobalConfiguration.DefaultServer))
                .AddService(ServiceLifetime.Singleton, sp => uriResolver ?? new ODataUriResolver())
                .AddService<IEnumerable<IODataRoutingConvention>>(ServiceLifetime.Singleton, sp =>
                        routingConventions ??
                            ODataRoutingConventions.CreateDefaultWithAttributeRouting(routeName, configuration)
                       )
                   );
       }