Prepare to replacing package buildable flag with enumeration

Note that changing the data member type is not automatically handled by the
ODB migration machinery. Thus, we split the schema change into two steps, with
this commit implementing the first step (see migrate/migrate.cxx for details).

1 files changed, 21 insertions, 2 deletions

diff --git a/migrate/migrate.cxx b/migrate/migrate.cxx
index 81c4543..1577f1b 100644
--- a/migrate/migrate.cxx
+++ b/migrate/migrate.cxx
@@ -206,7 +206,6 @@ create (database& db, bool extra_only) const
 
 // Register the data migration functions for the package database schema.
 //
-#if 0
 template <schema_version v>
 using package_migration_entry_base =
   data_migration_entry<v, LIBBREP_PACKAGE_SCHEMA_VERSION_BASE>;
@@ -218,11 +217,31 @@ struct package_migration_entry: package_migration_entry_base<v>
       : package_migration_entry_base<v> (f, "package") {}
 };
 
+// Migrate the package buildable member data while changing its type from
+// boolean to enumeration.
+
+// Note that changing the data member type is not automatically handled by the
+// migration machinery. Thus, we split the schema change into two steps,
+// delaying the second step until the next commit:
+//
+// - Rename the buildable data member column preserving its boolean type and
+//   migrate the data copying it from the original column into the new
+//   temporary column (package schema version 18). Note that the original
+//   column is deleted at the end of the migration.
+//
+// - Change the buildable data member type to the buildable_status
+//   enumeration, revert the column name and migrate the data by filling the
+//   originally-named column based on the temporary column (package schema
+//   version 19). Note that the temporary column is deleted at the end of the
+//   migration.
+//
 static const package_migration_entry<18>
 package_migrate_v18 ([] (database& db)
 {
+  // Copy the buildable flag values into the new temporary column.
+  //
+  db.execute ("UPDATE package SET buildable_ = buildable");
 });
-#endif
 
 // main() function
 //