[gnome-photos/sam/tracker3: 9/27] tracker 3: Check if variables are bound before querying

[Sam Thursfield <sthursfield src gnome org>]

commit 9d044fd3a35dd4ea8a6490fbdd25e47d72a184cd
Author: Sam Thursfield <sam afuera me uk>
Date:   Wed May 27 13:44:25 2020 +0200

    tracker 3: Check if variables are bound before querying
    
    This happened to work in Tracker 2, but in Tracker 3 it raises an
    assertion if you try to get the value of something that wasn't found.

 src/photos-base-item.c | 18 ++++++++++++++----
 1 file changed, 14 insertions(+), 4 deletions(-)
---
diff --git a/src/photos-base-item.c b/src/photos-base-item.c
index 143431f9..b34706f2 100644
--- a/src/photos-base-item.c
+++ b/src/photos-base-item.c
@@ -2756,6 +2756,16 @@ photos_base_item_update_info_from_type (PhotosBaseItem *self)
 }
 
 
+static gdouble
+get_double_with_default (TrackerSparqlCursor *cursor, PhotosQueryColumns column, gdouble default_value)
+{
+  if (tracker_sparql_cursor_is_bound (cursor, column)) {
+    return tracker_sparql_cursor_get_double (cursor, column);
+  } else {
+    return default_value;
+  }
+}
+
 static void
 photos_base_item_populate_from_cursor (PhotosBaseItem *self, TrackerSparqlCursor *cursor)
 {
@@ -2891,10 +2901,10 @@ photos_base_item_populate_from_cursor (PhotosBaseItem *self, TrackerSparqlCursor
       priv->width = height;
     }
 
-  priv->exposure_time = tracker_sparql_cursor_get_double (cursor, PHOTOS_QUERY_COLUMNS_EXPOSURE_TIME);
-  priv->fnumber = tracker_sparql_cursor_get_double (cursor, PHOTOS_QUERY_COLUMNS_FNUMBER);
-  priv->focal_length = tracker_sparql_cursor_get_double (cursor, PHOTOS_QUERY_COLUMNS_FOCAL_LENGTH);
-  priv->iso_speed = tracker_sparql_cursor_get_double (cursor, PHOTOS_QUERY_COLUMNS_ISO_SPEED);
+  priv->exposure_time = get_double_with_default (cursor, PHOTOS_QUERY_COLUMNS_EXPOSURE_TIME, 0.0);
+  priv->fnumber = get_double_with_default (cursor, PHOTOS_QUERY_COLUMNS_FNUMBER, 0.0);
+  priv->focal_length = get_double_with_default (cursor, PHOTOS_QUERY_COLUMNS_FOCAL_LENGTH, 0.0);
+  priv->iso_speed = get_double_with_default (cursor, PHOTOS_QUERY_COLUMNS_ISO_SPEED, 0.0);
 
   flash = tracker_sparql_cursor_get_string (cursor, PHOTOS_QUERY_COLUMNS_FLASH, NULL);
   priv->flash = g_quark_from_string (flash);