fix: user-feedback-on-schema-mismatch (#1558)

* validate schema version on restore

* show user error on backup failure

mealie/services/backups_v2/backup_file.py

@@ -5,6 +5,8 @@ from pathlib import Path
 
 
 class BackupContents:
+    _tables: dict = None
+
     def __init__(self, file: Path) -> None:
         self.base = file
         self.data_directory = self.base / "data"
@@ -22,9 +24,22 @@ class BackupContents:
 
         return True
 
+    def schema_version(self) -> str:
+        tables = self.read_tables()
+
+        alembic_version = tables.get("alembic_version", [])
+
+        if not alembic_version:
+            return ""
+
+        return alembic_version[0].get("version_num", "")
+
     def read_tables(self) -> dict:
-        with open(self.tables) as f:
-            return json.loads(f.read())
+        if self._tables is None:
+            with open(self.tables, "r") as f:
+                self._tables = json.load(f)
+
+        return self._tables
 
 
 class BackupFile:

mealie/services/backups_v2/backup_v2.py

@@ -9,6 +9,10 @@ from mealie.services.backups_v2.alchemy_exporter import AlchemyExporter
 from mealie.services.backups_v2.backup_file import BackupFile
 
 
+class BackupSchemaMismatch(Exception):
+    ...
+
+
 class BackupV2(BaseService):
     def __init__(self, db_url: str = None) -> None:
         super().__init__()
@@ -73,18 +77,28 @@ class BackupV2(BaseService):
             self._postgres()
 
         with backup as contents:
+            # ================================
+            # Validation
             if not contents.validate():
                 self.logger.error(
                     "Invalid backup file. file does not contain required elements (data directory and database.json"
                 )
                 raise ValueError("Invalid backup file")
 
-            # Purge the Database
+            database_json = contents.read_tables()
+
+            if not AlchemyExporter.validate_schemas(database_json, self.db_exporter.dump()):
+                self.logger.error("Invalid backup file. Database schemas do not match")
+                raise BackupSchemaMismatch("Invalid backup file. Database schemas do not match")
+
+            # ================================
+            # Purge Database
 
             self.logger.info("dropping all database tables")
             self.db_exporter.drop_all()
 
-            database_json = contents.read_tables()
+            # ================================
+            # Restore Database
 
             self.logger.info("importing database tables")
             self.db_exporter.restore(database_json)