service/datastore: misc improvements in properties.go

service/datastore/propertytype_string.go

+// generated by stringer -type=PropertyType; DO NOT EDIT
+
+package datastore
+
+import "fmt"
+
+const _PropertyType_name = "PTNullPTIntPTTimePTBoolPTBytesPTStringPTFloatPTGeoPointPTKeyPTBlobKeyPTUnknown"
+
+var _PropertyType_index = [...]uint8{0, 6, 11, 17, 23, 30, 38, 45, 55, 60, 69, 78}
+
+func (i PropertyType) String() string {
+        if i >= PropertyType(len(_PropertyType_index)-1) {
+                return fmt.Sprintf("PropertyType(%d)", i)
+        }
+        return _PropertyType_name[_PropertyType_index[i]:_PropertyType_index[i+1]]
+}