Added Database Schema checks

The database schema is now checked if the correct (and only the correct) tables are present.

ArtNet/db/db_adapter.py

@@ -5,6 +5,9 @@ from psycopg2.errorcodes import UNIQUE_VIOLATION
 
 class DBAdapter:
 
+    EXPECTED_TABLES = ['art', 'artist', 'tag', 'topic', 'presence', 'artist_topic', 'art_author',
+                       'art_tag', 'tag_alias', 'tag_implication', 'tag_category']
+
     def __init__(self, user: str, password: str, host: str = "localhost", port: int = 5432, database: str = "artnet"):
         self.db = None
         self.db_cursor = None
@@ -16,6 +19,34 @@ class DBAdapter:
             raise ValueError("Invalid DB credentials!")
         print("DB connection to {0}:{1}/{2}".format(host, port, database))
 
+        if not self.check_tables():
+            raise ValueError("Invalid DB schema")
+
+    def check_tables(self) -> bool:
+        """
+        Check if all the expected tables are present in the connected database.
+        :return:
+        """
+        self.db_cursor.execute("select relname from pg_class where relkind='r' and relname !~ '^(pg_|sql_)';")
+        present_tables = self.db_cursor.fetchall()
+        unknown_tables = []
+        missing = [x for x in DBAdapter.EXPECTED_TABLES]
+        for table in present_tables:
+            table = table[0]
+            if table not in DBAdapter.EXPECTED_TABLES:
+                unknown_tables.append(table)
+            else:
+                missing.remove(table)
+
+        if len(missing) > 0:
+            print("The following tables are missing from the currently connected database: {0}".format(missing))
+            return False
+
+        if len(unknown_tables) > 0:
+            print("The following tables are unknown and not expected inside the database: {0}".format(unknown_tables))
+
+        return True
+
     def save_image(self, ID: str, title: str, authors: list, path: str, tags: list, link: str, md5_hash: str):
         """
         Updates or saves the given image data to the DB