Add Discriminator Serialization policy (auto/always/never)

dahomey-technologies · Sep 12, 2019 · cd99186 · cd99186
1 parent 898dd4a
commit cd99186
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Showing 10 changed files with 143 additions and 30 deletions.
diff --git a/src/Dahomey.Cbor.Tests/DiscriminatorTests.cs b/src/Dahomey.Cbor.Tests/DiscriminatorTests.cs
@@ -0,0 +1,51 @@
+using Dahomey.Cbor.Attributes;
+using Xunit;
+
+namespace Dahomey.Cbor.Tests
+{
+    public class DiscriminatorTests
+    {
+        [Fact]
+        public void ReadPolymorphicObject()
+        {
+            const string hexBuffer = "A16A426173654F626A656374A3625F746A4E616D654F626A656374644E616D6563666F6F62496401";
+            BaseObjectHolder obj = Helper.Read<BaseObjectHolder>(hexBuffer);
+        }
+
+        [Theory]
+        [InlineData(CborDiscriminatorPolicy.Default, "A26A426173654F626A656374A3625F746A4E616D654F626A656374644E616D6563666F6F624964016A4E616D654F626A656374A2644E616D656362617262496402")]
+        [InlineData(CborDiscriminatorPolicy.Auto, "A26A426173654F626A656374A3625F746A4E616D654F626A656374644E616D6563666F6F624964016A4E616D654F626A656374A2644E616D656362617262496402")]
+        [InlineData(CborDiscriminatorPolicy.Never, "A26A426173654F626A656374A2644E616D6563666F6F624964016A4E616D654F626A656374A2644E616D656362617262496402")]
+        [InlineData(CborDiscriminatorPolicy.Always, "A26A426173654F626A656374A3625F746A4E616D654F626A656374644E616D6563666F6F624964016A4E616D654F626A656374A3625F746A4E616D654F626A656374644E616D656362617262496402")]
+        public void WritePolymorphicObject(CborDiscriminatorPolicy discriminatorPolicy, string hexBuffer)
+        {
+            CborOptions options = new CborOptions();
+            options.Registry.ObjectMappingRegistry.Register<NameObject>(om =>
+            {
+                om.AutoMap();
+                om.SetDiscriminatorPolicy(discriminatorPolicy);
+            });
+            options.Registry.ObjectMappingRegistry.Register<BaseObject>(om =>
+            {
+                om.AutoMap();
+                om.SetDiscriminatorPolicy(discriminatorPolicy);
+            });
+
+            BaseObjectHolder obj = new BaseObjectHolder
+            {
+                BaseObject = new NameObject
+                {
+                    Id = 1,
+                    Name = "foo"
+                },
+                NameObject = new NameObject
+                {
+                    Id = 2,
+                    Name = "bar"
+                }
+            };
+
+            Helper.TestWrite(obj, hexBuffer, null, options);
+        }
+    }
+}
diff --git a/src/Dahomey.Cbor.Tests/Issues/Issue0027.cs b/src/Dahomey.Cbor.Tests/Issues/Issue0027.cs
@@ -0,0 +1,26 @@
+using Dahomey.Cbor.Attributes;
+using Xunit;
+
+namespace Dahomey.Cbor.Tests.Issues
+{
+    public class Issue0027
+    {
+        [CborDiscriminator("somediscriminator", Policy = CborDiscriminatorPolicy.Always)]
+        public class Car
+        {
+            public string Description { get; set; }
+        }
+
+        [Fact]
+        public void Test()
+        {
+            var car = new Car()
+            {
+                Description = "n"
+            };
+
+            string hexBuffer = "A2625F7471736F6D656469736372696D696E61746F726B4465736372697074696F6E616E";
+            Helper.TestWrite(car, hexBuffer);
+        }
+    }
+}
diff --git a/src/Dahomey.Cbor.Tests/ObjectTests.cs b/src/Dahomey.Cbor.Tests/ObjectTests.cs
@@ -449,28 +449,6 @@ public void ReadWithNamingConvention()
             Assert.Equal(12, obj.MyValue);
         }
 
-        [Fact]
-        public void ReadPolymorphicObject()
-        {
-            const string hexBuffer = "A16A426173654F626A656374A3625F746A4E616D654F626A656374644E616D6563666F6F62496401";
-            BaseObjectHolder obj = Helper.Read<BaseObjectHolder>(hexBuffer);
-        }
-
-        [Fact]
-        public void WritePolymorphicObject()
-        {
-            const string hexBuffer = "A16A426173654F626A656374A3625F746A4E616D654F626A656374644E616D6563666F6F62496401";
-            BaseObjectHolder obj = new BaseObjectHolder
-            {
-                BaseObject = new NameObject
-                {
-                    Id = 1,
-                    Name = "foo"
-                }
-            };
-            Helper.TestWrite(obj, hexBuffer);
-        }
-
         [Fact]
         public void ReadWithCustomConverterOnProperty()
         {

diff --git a/src/Dahomey.Cbor.Tests/SampleClasses.cs b/src/Dahomey.Cbor.Tests/SampleClasses.cs
@@ -160,6 +160,7 @@ public class ObjectWithNamingConvention
     public class BaseObjectHolder
     {
         public BaseObject BaseObject { get; set; }
+        public NameObject NameObject { get; set; }
     }
 
     public class BaseObject

diff --git a/src/Dahomey.Cbor/Attributes/CborDiscriminatorAttribute.cs b/src/Dahomey.Cbor/Attributes/CborDiscriminatorAttribute.cs
@@ -2,6 +2,29 @@
 
 namespace Dahomey.Cbor.Attributes
 {
+    /// <summary>
+    /// Specify the discriminators serialization policy
+    /// </summary>
+    public enum CborDiscriminatorPolicy
+    {
+        Default = 0,
+
+        /// <summary>
+        /// Discriminator will never be written
+        /// </summary>
+        Never,
+
+        /// <summary>
+        /// Discriminator will always be written
+        /// </summary>
+        Always,
+
+        /// <summary>
+        /// Discriminator will be written only if the declaring type and the actual type of the object being written differ.
+        /// </summary>
+        Auto
+    }
+
     [AttributeUsage(AttributeTargets.Class)]
     public class CborDiscriminatorAttribute : Attribute
     {
@@ -11,5 +34,7 @@ public CborDiscriminatorAttribute(string discriminator)
         }
 
         public string Discriminator { get; set; }
+
+        public CborDiscriminatorPolicy Policy { get; set; }
     }
 }
diff --git a/src/Dahomey.Cbor/CborOptions.cs b/src/Dahomey.Cbor/CborOptions.cs
@@ -1,4 +1,5 @@
-using Dahomey.Cbor.Serialization;
+using Dahomey.Cbor.Attributes;
+using Dahomey.Cbor.Serialization;
 using Dahomey.Cbor.Serialization.Conventions;
 
 namespace Dahomey.Cbor
@@ -31,6 +32,7 @@ public class CborOptions
         public DateTimeFormat DateTimeFormat { get; set; }
         public bool IsIndented { get; set; }
         public IDiscriminatorConvention DiscriminatorConvention { get; set; }
+        public CborDiscriminatorPolicy DiscriminatorPolicy { get; set; }
 
         public CborOptions()
         {

diff --git a/src/Dahomey.Cbor/Serialization/Converters/Mappings/DefaultObjectMappingConvention.cs b/src/Dahomey.Cbor/Serialization/Converters/Mappings/DefaultObjectMappingConvention.cs
@@ -28,6 +28,11 @@ public class DefaultObjectMappingConvention : IObjectMappingConvention
 
             registry.DefaultDiscriminatorConvention.RegisterType(type, discriminator);
 
+            if (discriminatorAttribute != null)
+            {
+                objectMapping.SetDiscriminatorPolicy(discriminatorAttribute.Policy);
+            }
+
             Type namingConventionType = type.GetCustomAttribute<CborNamingConventionAttribute>()?.NamingConventionType;
             if (namingConventionType != null)
             {

diff --git a/src/Dahomey.Cbor/Serialization/Converters/Mappings/IObjectMapping.cs b/src/Dahomey.Cbor/Serialization/Converters/Mappings/IObjectMapping.cs
@@ -1,4 +1,5 @@
-using Dahomey.Cbor.Serialization.Conventions;
+using Dahomey.Cbor.Attributes;
+using Dahomey.Cbor.Serialization.Conventions;
 using System;
 using System.Collections.Generic;
 
@@ -14,5 +15,6 @@ public interface IObjectMapping : IMappingInitialization
         Delegate OnSerializedMethod { get; }
         Delegate OnDeserializingMethod { get; }
         Delegate OnDeserializedMethod { get; }
+        CborDiscriminatorPolicy DiscriminatorPolicy { get; }
     }
 }
diff --git a/src/Dahomey.Cbor/Serialization/Converters/Mappings/ObjectMapping.cs b/src/Dahomey.Cbor/Serialization/Converters/Mappings/ObjectMapping.cs
@@ -1,4 +1,5 @@
-using Dahomey.Cbor.Serialization.Conventions;
+using Dahomey.Cbor.Attributes;
+using Dahomey.Cbor.Serialization.Conventions;
 using Dahomey.Cbor.Util;
 using System;
 using System.Collections.Generic;
@@ -28,6 +29,7 @@ public class ObjectMapping<T> : IObjectMapping
         public Delegate OnSerializedMethod { get; private set; }
         public Delegate OnDeserializingMethod { get; private set; }
         public Delegate OnDeserializedMethod { get; private set; }
+        public CborDiscriminatorPolicy DiscriminatorPolicy { get; private set; }
 
         public ObjectMapping(SerializationRegistry registry)
         {
@@ -186,6 +188,12 @@ public ObjectMapping<T> SetOnDeserializedMethod(Action<T> onDeserializedMethod)
             return this;
         }
 
+        public ObjectMapping<T> SetDiscriminatorPolicy(CborDiscriminatorPolicy discriminatorPolicy)
+        {
+            DiscriminatorPolicy = discriminatorPolicy;
+            return this;
+        }
+
         public void Initialize()
         {
             foreach(IMemberMapping mapping in _memberMappings)

diff --git a/src/Dahomey.Cbor/Serialization/Converters/ObjectConverter.cs b/src/Dahomey.Cbor/Serialization/Converters/ObjectConverter.cs
@@ -1,9 +1,9 @@
-using Dahomey.Cbor.Serialization.Conventions;
+using Dahomey.Cbor.Attributes;
+using Dahomey.Cbor.Serialization.Conventions;
 using Dahomey.Cbor.Serialization.Converters.Mappings;
 using Dahomey.Cbor.Util;
 using System;
 using System.Collections.Generic;
-using System.ComponentModel;
 using System.Linq;
 using System.Reflection;
 
@@ -209,17 +209,32 @@ public override void Write(ref CborWriter writer, T value)
                 obj = value,
             };
 
-            if (_objectMapping.CreatorMapping == null && value.GetType() != typeof(T))
+            Type declaredType = typeof(T);
+            Type actualType = value.GetType();
+
+            if (_objectMapping.CreatorMapping == null && actualType != declaredType)
             {
-                context.state = MapWriterContext.State.Discriminator;
                 context.objectConverter = (IObjectConverter)_registry.ConverterRegistry.Lookup(value.GetType());
             }
             else
             {
-                context.state = MapWriterContext.State.Properties;
                 context.objectConverter = this;
             }
 
+            CborDiscriminatorPolicy discriminatorPolicy = _objectMapping.DiscriminatorPolicy != CborDiscriminatorPolicy.Default ? _objectMapping.DiscriminatorPolicy
+                : (writer.Options.DiscriminatorPolicy != CborDiscriminatorPolicy.Default ? writer.Options.DiscriminatorPolicy : CborDiscriminatorPolicy.Auto);
+
+            if (_objectMapping.CreatorMapping == null &&
+                (discriminatorPolicy == CborDiscriminatorPolicy.Always
+                || discriminatorPolicy == CborDiscriminatorPolicy.Auto && actualType != declaredType))
+            {
+                context.state = MapWriterContext.State.Discriminator;
+            }
+            else
+            {
+                context.state = MapWriterContext.State.Properties;
+            }
+
             writer.WriteMap(this, ref context);
 
             if (_objectMapping.OnSerializedMethod != null)