[tracker/wip/carlosg/backports-3.3: 3/7] core: Handle conversion of values for superproperties with differing types

[Carlos Garnacho <carlosg src gnome org>]

commit 5bd60c940ba89d64377bf96a1749f5874fe35eff
Author: Carlos Garnacho <carlosg gnome org>
Date:   Thu Jun 30 00:30:36 2022 +0200

    core: Handle conversion of values for superproperties with differing types
    
    This is not quite correct, but it is the most straightforward way to sort
    of handle situations in our own Nepomuk ontology that superproperties have
    different rdfs:range than their subproperties.
    
    For these cases, handle the conversion of the value. Since the worst case
    (and the one we happen to exercise) is about converting resource ROWIDs to
    strings, handle this specific situation.
    
    This helps in serialization and deserialization of this data, since the
    ROWIDs were not something that could be replicated in other databases
    without mismatches (e.g. the resource having a different ROWID in the
    new database importing the data) or worse (e.g. cardinality or other
    constraints broken).

 src/libtracker-data/tracker-data-update.c | 60 +++++++++++++++++++++++++++++--
 1 file changed, 58 insertions(+), 2 deletions(-)
---
diff --git a/src/libtracker-data/tracker-data-update.c b/src/libtracker-data/tracker-data-update.c
index 2b5935a1a..bee4fcc50 100644
--- a/src/libtracker-data/tracker-data-update.c
+++ b/src/libtracker-data/tracker-data-update.c
@@ -1775,6 +1775,36 @@ process_domain_indexes (TrackerData     *data,
        }
 }
 
+static gboolean
+maybe_convert_value (TrackerData         *data,
+                     TrackerPropertyType  source,
+                     TrackerPropertyType  target,
+                     const GValue        *value,
+                     GValue              *value_out)
+{
+       if (source == TRACKER_PROPERTY_TYPE_RESOURCE &&
+           target == TRACKER_PROPERTY_TYPE_STRING &&
+           G_VALUE_HOLDS_INT64 (value)) {
+               TrackerDBInterface *iface;
+               gchar *str;
+
+               iface = tracker_data_manager_get_writable_db_interface (data->manager);
+               str = tracker_data_query_resource_urn (data->manager, iface,
+                                                      g_value_get_int64 (value));
+
+               if (!str) {
+                       str = g_strdup_printf ("urn:bnode:%" G_GINT64_FORMAT,
+                                              g_value_get_int64 (value));
+               }
+
+               g_value_init (value_out, G_TYPE_STRING);
+               g_value_take_string (value_out, str);
+               return TRUE;
+       }
+
+       return FALSE;
+}
+
 static gboolean
 cache_insert_metadata_decomposed (TrackerData      *data,
                                   TrackerProperty  *property,
@@ -1806,6 +1836,8 @@ cache_insert_metadata_decomposed (TrackerData      *data,
        while (*super_properties) {
                gboolean super_is_multi;
                GArray *super_old_values;
+               GValue converted = G_VALUE_INIT;
+               const GValue *val;
 
                super_is_multi = tracker_property_get_multiple_values (*super_properties);
                super_old_values = get_old_property_values (data, *super_properties, &new_error);
@@ -1817,14 +1849,25 @@ cache_insert_metadata_decomposed (TrackerData      *data,
                data->resource_buffer->fts_updated |=
                        tracker_property_get_fulltext_indexed (*super_properties);
 
+               if (maybe_convert_value (data,
+                                        tracker_property_get_data_type (property),
+                                        tracker_property_get_data_type (*super_properties),
+                                        object,
+                                        &converted))
+                       val = &converted;
+               else
+                       val = object;
+
                if (super_is_multi || super_old_values->len == 0) {
-                       change |= cache_insert_metadata_decomposed (data, *super_properties, object,
+                       change |= cache_insert_metadata_decomposed (data, *super_properties, val,
                                                                    &new_error);
                        if (new_error) {
+                               g_value_unset (&converted);
                                g_propagate_error (error, new_error);
                                return FALSE;
                        }
                }
+               g_value_unset (&converted);
                super_properties++;
        }
 
@@ -1951,8 +1994,21 @@ delete_metadata_decomposed (TrackerData      *data,
        /* also delete super property values */
        super_properties = tracker_property_get_super_properties (property);
        while (*super_properties) {
-               change |= delete_metadata_decomposed (data, *super_properties, object, error);
+               GValue converted = G_VALUE_INIT;
+               const GValue *val;
+
+               if (maybe_convert_value (data,
+                                        tracker_property_get_data_type (property),
+                                        tracker_property_get_data_type (*super_properties),
+                                        object,
+                                        &converted))
+                       val = &converted;
+               else
+                       val = object;
+
+               change |= delete_metadata_decomposed (data, *super_properties, val, error);
                super_properties++;
+               g_value_unset (&converted);
        }
 
        return change;