Minor changes

workitem/enum_type.go

@@ -157,15 +157,17 @@ func containsAll(a []interface{}, v []interface{}) bool {
 	return result
 }
 
+// ConvertFromModel implements the FieldType interface
 func (t EnumType) ConvertFromModel(value interface{}) (interface{}, error) {
+	if value == nil {
+		return nil, nil
+	}
 	converted, err := t.BaseType.ConvertFromModel(value)
 	if err != nil {
 		return nil, fmt.Errorf("error converting enum value: %s", err.Error())
 	}
-	if value != nil {
-		if !contains(t.Values, converted) {
-			return nil, fmt.Errorf("value: %+v (%[1]T) is not part of allowed enum values: %+v", value, t.Values)
-		}
+	if !contains(t.Values, converted) {
+		return nil, fmt.Errorf("value: %+v (%[1]T) is not part of allowed enum values: %+v", value, t.Values)
 	}
 	return converted, nil
 }

workitem/enum_type_blackbox_test.go

@@ -345,11 +345,11 @@ func TestEnumType_ConvertFromModel(t *testing.T) {
 			},
 			[]testCase{
 				{"ok", "second", "second", false},
+				{"ok - nil", nil, nil, false},
 				{"fail - invalid string", "fourth", nil, true},
 				{"fail - int", 11, nil, true},
 				{"fail - float", 1.3, nil, true},
 				{"fail - empty string", "", nil, true},
-				{"fail - nil", nil, nil, true},
 				{"fail - list", []string{"x", "y"}, nil, true},
 			},
 		},
@@ -362,11 +362,11 @@ func TestEnumType_ConvertFromModel(t *testing.T) {
 			},
 			[]testCase{
 				{"ok", 4, 4, false},
+				{"ok - nil", nil, nil, false},
 				{"fail - invalid int", 2, nil, true},
 				{"fail - string", "11", nil, true},
 				{"fail - float", 1.3, nil, true},
 				{"fail - bool", true, nil, true},
-				{"fail - nil", nil, nil, true},
 				{"fail - list", []string{"x", "y"}, nil, true},
 			},
 		},
@@ -379,12 +379,12 @@ func TestEnumType_ConvertFromModel(t *testing.T) {
 			},
 			[]testCase{
 				{"ok", 1.1, 1.1, false},
+				{"ok - nil", nil, nil, false},
 				{"fail - invalid float", 4.4, nil, true},
 				{"fail - int", 1, nil, true},
 				{"fail - string", "11", nil, true},
 				{"fail - bool", true, nil, true},
 				{"fail - list", []string{"x", "y"}, nil, true},
-				{"fail - nil", nil, nil, true},
 			},
 		},
 	}

workitem/simple_type.go

@@ -171,7 +171,7 @@ func (t SimpleType) ConvertToModel(value interface{}) (interface{}, error) {
 	}
 }
 
-// ConvertFromModel implements the t interface
+// ConvertFromModel implements the FieldType interface
 func (t SimpleType) ConvertFromModel(value interface{}) (interface{}, error) {
 	if value == nil {
 		return nil, nil