Re-fixes the issue with using IDataValueSetter.SetValue on the DefaultData implementation and ensures that when there is a null value that it reverts to an empty string since this was what the default value was in the Value getter of DefaultData when there was no value. Have added a couple unit tests to support.

Shazwazza · Shazwazza · commit 5989d19f7f25 · 2013-09-02T13:27:48.000+10:00
diff --git a/src/Umbraco.Core/Models/PropertyExtensions.cs b/src/Umbraco.Core/Models/PropertyExtensions.cs
@@ -43,7 +43,7 @@ internal static XElement ToXml(this Property property, IDataTypeService dataType
             //This seems to fail during testing 
             //SD: With the new null checks below, this shouldn't fail anymore.
             var dt = property.PropertyType.DataType(property.Id, dataTypeService);
-            if (dt != null && dt.Data != null && dt.Data.Value != null)
+            if (dt != null && dt.Data != null)
             {
                 //We've already got the value for the property so we're going to give it to the 
                 // data type's data property so it doesn't go re-look up the value from the db again.
diff --git a/src/Umbraco.Tests/Models/DataValueSetterTests.cs b/src/Umbraco.Tests/Models/DataValueSetterTests.cs
@@ -66,8 +66,7 @@ public void SetValue_Is_Called_When_Executing_ToXml_On_A_Property_With_DataType_
             var dataTypeId = Guid.NewGuid();
             
             var dataTypeData = MockRepository.GenerateMock<IData, IDataValueSetter>();
-            //needs to have a value for SetValue to be called
-            dataTypeData.Stub(data => data.Value).Return(string.Empty);
+            
             dataTypeData
                 .Stub(data => data.ToXMl(Arg<XmlDocument>.Is.Anything))
                 .Return(null) // you have to call Return() even though we're about to override it
@@ -100,5 +99,18 @@ public void SetValue_Is_Called_When_Executing_ToXml_On_A_Property_With_DataType_
             ((IDataValueSetter)dataTypeData).AssertWasCalled(setter => setter.SetValue("Hello world", DataTypeDatabaseType.Nvarchar.ToString()));
         }
 
+        [TestCase(DataTypeDatabaseType.Nvarchar)]
+        [TestCase(DataTypeDatabaseType.Date)]
+        [TestCase(DataTypeDatabaseType.Integer)]
+        [TestCase(DataTypeDatabaseType.Ntext)]
+        public void DefaultData_SetValue_Ensures_Empty_String_When_Null_Value_Any_Data_Type(DataTypeDatabaseType type)
+        {
+            var defaultData = new DefaultData(MockRepository.GenerateMock<BaseDataType>());
+
+            ((IDataValueSetter)defaultData).SetValue(null, type.ToString());
+
+            Assert.AreEqual(string.Empty, defaultData.Value);
+        }
+
     }
 }
diff --git a/src/umbraco.cms/businesslogic/datatype/DefaultData.cs b/src/umbraco.cms/businesslogic/datatype/DefaultData.cs
@@ -65,6 +65,17 @@ public virtual void Initialize(object InitValue, int InitPropertyId)
         /// <param name="strDbType"></param>
         void IDataValueSetter.SetValue(object val, string strDbType)
         {
+            //We need to ensure that val is not a null value, if it is then we'll convert this to an empty string.
+            //The reason for this is because by default the DefaultData.Value property returns an empty string when 
+            // there is no value, this is based on the PropertyDataDto.GetValue return value which defaults to an 
+            // empty string (which is called from this class's method LoadValueFromDatabase). 
+            //Some legacy implementations of DefaultData are expecting an empty string when there is 
+            // no value so we need to keep this consistent.
+            if (val == null)
+            {
+                val = string.Empty;
+            }
+
             _value = val;
             //now that we've set our value, we can update our BaseDataType object with the correct values from the db
             //instead of making it query for itself. This is a peformance optimization enhancement.

Original file line number	Diff line number	Diff line change
`@@ -43,7 +43,7 @@ internal static XElement ToXml(this Property property, IDataTypeService dataType`
`43`	`43`	`//This seems to fail during testing`
`44`	`44`	`//SD: With the new null checks below, this shouldn't fail anymore.`
`45`	`45`	`var dt = property.PropertyType.DataType(property.Id, dataTypeService);`
`46`		`- if (dt != null && dt.Data != null && dt.Data.Value != null)`
	`46`	`+ if (dt != null && dt.Data != null)`
`47`	`47`	`{`
`48`	`48`	`//We've already got the value for the property so we're going to give it to the`
`49`	`49`	`// data type's data property so it doesn't go re-look up the value from the db again.`