Fixed default value when there value is NOT DbNull

src/DbReader.Tests/InstanceReaderTests.cs

@@ -410,6 +410,17 @@ public void ShouldUseDefaultValue()
             instance.Property.Value.ShouldBe(42);
         }
 
+        [Fact]
+        public void ShouldNotUseDefaultValue()
+        {
+            var dataRecord = new { Id = 1, Property = 42 }.ToDataRecord();
+            DbReaderOptions.WhenReading<CustomValueType>().Use((dr, i) => new CustomValueType(dr.GetInt32(i))).WithDefaultValue(new CustomValueType(82));
+            var reader = GetReader<ClassWithProperty<CustomValueType>>();
+            var instance = reader.Read(dataRecord, string.Empty);
+            instance.Property.Value.ShouldBe(42);
+        }
+
+
 
         public class CustomValueType
         {

src/DbReader/Construction/ConstructorReaderMethodBuilder.cs

@@ -10,7 +10,7 @@
     /// an instance of <typeparamref name="T"/> using constructor arguments.
     /// </summary>
     /// <typeparam name="T">The type of object to be created.</typeparam>
-    public class ConstructorReaderMethodBuilder<T> : ReaderMethodBuilder<T> 
+    public class ConstructorReaderMethodBuilder<T> : ReaderMethodBuilder<T>
     {
         private readonly IConstructorSelector constructorSelector;
 
@@ -50,7 +50,7 @@ private void LoadConstructorArguments(ILGenerator il, ConstructorInfo constructo
             for (int parameterIndex = 0; parameterIndex < parameters.Length; parameterIndex++)
             {
                 EmitCheckForValidOrdinal(il, parameterIndex, tryLoadNullValue);
-                EmitCheckForDbNull(il, parameterIndex, tryLoadNullValue);
+                EmitGoLabelIfDbNull(il, parameterIndex, tryLoadNullValue);
             }
 
             for (int i = 0; i < parameters.Length; i++)

src/DbReader/Construction/PropertyReaderMethodBuilder.cs

@@ -133,13 +133,16 @@ private void EmitPropertySetters(ILGenerator generator, LocalBuilder instanceVar
         private void EmitPropertySetter(ILGenerator il, PropertyInfo property, int propertyIndex, LocalBuilder instanceVariable)
         {
             MethodInfo getMethod = MethodSelector.Execute(property.PropertyType);
+            var checkForDefaultValueLabel = il.DefineLabel();
             var endLabel = il.DefineLabel();
-            EmitCheckForValidOrdinal(il, propertyIndex, endLabel);
-            EmitCheckForDbNull(il, propertyIndex, endLabel);
+            EmitCheckForValidOrdinal(il, propertyIndex, checkForDefaultValueLabel);
+            EmitGoLabelIfDbNull(il, propertyIndex, checkForDefaultValueLabel);
             LoadInstance(il, instanceVariable);
             EmitGetValue(il, propertyIndex, getMethod, property.PropertyType);
             EmitCallPropertySetterMethod(il, property);
-            il.MarkLabel(endLabel);
+            il.MarkLabel(checkForDefaultValueLabel);
+            EmitCheckForValidOrdinal(il, propertyIndex, endLabel);
+            EmitGoLabelIfNotDbNull(il, propertyIndex, endLabel);
             if (ValueConverter.HasDefaultValue(property.PropertyType))
             {
                 var openGenericGetDefaultValueMethod = typeof(ValueConverter).GetMethod(nameof(ValueConverter.GetDefaultValue), BindingFlags.Static | BindingFlags.NonPublic);
@@ -148,6 +151,7 @@ private void EmitPropertySetter(ILGenerator il, PropertyInfo property, int prope
                 il.Emit(OpCodes.Call, getDefaultValueMethod);
                 EmitCallPropertySetterMethod(il, property);
             }
+            il.MarkLabel(endLabel);
         }
     }
 }

src/DbReader/Construction/ReaderMethodBuilder.cs

@@ -66,7 +66,7 @@
             LoadOrdinal(il, index);
             LoadIntegerValueOfMinusOne(il);
             EmitCompareValues(il);
-            EmitGotoEndLabelIfValueIsTrue(il, trueLabel);
+            EmitGotoLabelIfValueIsTrue(il, trueLabel);
         }
 
         /// <summary>
@@ -76,12 +76,20 @@
         /// <param name="index">The index of the ordinal to check.</param>
         /// <param name="trueLabel">The <see cref="Label"/> that represents where to jump if 
         /// the value about to be read from the <see cref="IDataRecord"/> is <see cref="DBNull"/>.</param>
-        protected void EmitCheckForDbNull(ILGenerator il, int index, Label trueLabel)
+        protected void EmitGoLabelIfDbNull(ILGenerator il, int index, Label trueLabel)
         {
             LoadDataRecord(il);
             LoadOrdinal(il, index);
             EmitCallIsDbNullMethod(il);
-            EmitGotoEndLabelIfValueIsTrue(il, trueLabel);
+            EmitGotoLabelIfValueIsTrue(il, trueLabel);
+        }
+
+        protected void EmitGoLabelIfNotDbNull(ILGenerator il, int index, Label falseLabel)
+        {
+            LoadDataRecord(il);
+            LoadOrdinal(il, index);
+            EmitCallIsDbNullMethod(il);
+            EmitGotoLabelIfValueIsFalse(il, falseLabel);
         }
 
         /// <summary>
@@ -168,9 +176,14 @@
             il.Emit(OpCodes.Ceq);
         }
 
-        private static void EmitGotoEndLabelIfValueIsTrue(ILGenerator il, Label endLabel)
+        private static void EmitGotoLabelIfValueIsTrue(ILGenerator il, Label trueLabel)
+        {
+            il.Emit(OpCodes.Brtrue, trueLabel);
+        }
+
+        private static void EmitGotoLabelIfValueIsFalse(ILGenerator il, Label trueLabel)
         {
-            il.Emit(OpCodes.Brtrue, endLabel);
+            il.Emit(OpCodes.Brfalse, trueLabel);
         }
 
         private static Func<IDataRecord, int[], T> CreateDelegate(IMethodSkeleton methodSkeleton)