Document export size estimation APIexport-size-estimation-api

Signed-off-by: Christopher Ng <chrng8@gmail.com>

1 files changed, 13 insertions, 1 deletions

diff --git a/developer_manual/digging_deeper/user_migration.rst b/developer_manual/digging_deeper/user_migration.rst
index ff4798ddb..4e0b73611 100644
--- a/developer_manual/digging_deeper/user_migration.rst
+++ b/developer_manual/digging_deeper/user_migration.rst
@@ -30,12 +30,13 @@ whenever a user export or import begins.
   use OCP\UserMigration\IExportDestination;
   use OCP\UserMigration\IImportSource;
   use OCP\UserMigration\IMigrator;
+  use OCP\UserMigration\ISizeEstimationMigrator;
   use OCP\UserMigration\TMigratorBasicVersionHandling;
   use OCP\UserMigration\UserMigrationException;
   use Symfony\Component\Console\Output\OutputInterface;
   use Throwable;
 
-  class MyAppMigrator implements IMigrator {
+  class MyAppMigrator implements IMigrator, ISizeEstimationMigrator {
     use TMigratorBasicVersionHandling;
 
     private IMyAppManager $myAppManager;
@@ -55,6 +56,17 @@ whenever a user export or import begins.
     }
 
     /**
+     * Returns an estimate of the exported data size in KiB.
+     * Should be fast, favor performance over accuracy.
+     *
+     * @since 25.0.0
+     */
+    public function getEstimatedExportSize(IUser $user): int {
+      $size = 100; // 100KiB for user data JSON
+      return $size;
+    }
+
+    /**
      * Export user data
      *
      * @throws UserMigrationException