Refactor updates of relations tables.

[plomtask] / plomtask / db.py

diff --git a/plomtask/db.py b/plomtask/db.py
index e0a5d4f5df5426512c8a7552ca889c598dcaabfe..bf633e2c9826f464c690b03b75dfda4a33df7234 100644 (file)
--- a/plomtask/db.py
+++ b/plomtask/db.py
@@ -1,9 +1,9 @@
 """Database management."""
 from os.path import isfile
 from difflib import Differ
-from sqlite3 import connect as sql_connect, Cursor
-from typing import Any
-from plomtask.misc import HandledException
+from sqlite3 import connect as sql_connect, Cursor, Row
+from typing import Any, Dict
+from plomtask.exceptions import HandledException
 
 PATH_DB_SCHEMA = 'scripts/init.sql'
 
@@ -23,7 +23,7 @@ class DatabaseFile:  # pylint: disable=too-few-public-methods
         self._check()
 
     def _check(self) -> None:
-        """Check file exists and is of proper schema."""
+        """Check file exists, and is of proper schema."""
         self.exists = isfile(self.path)
         if self.exists:
             self._validate_schema()
@@ -49,6 +49,11 @@ class DatabaseConnection:
     def __init__(self, db_file: DatabaseFile) -> None:
         self.file = db_file
         self.conn = sql_connect(self.file.path)
+        self.cached_todos: Dict[int, Any] = {}
+        self.cached_days: Dict[str, Any] = {}
+        self.cached_process_steps: Dict[int, Any] = {}
+        self.cached_processes: Dict[int, Any] = {}
+        self.cached_conditions: Dict[int, Any] = {}
 
     def commit(self) -> None:
         """Commit SQL transaction."""
@@ -61,3 +66,75 @@ class DatabaseConnection:
     def close(self) -> None:
         """Close DB connection."""
         self.conn.close()
+
+    def rewrite_relations(self, table_name: str, key: str, target: int,
+                          rows: list[list[Any]]) -> None:
+        """Rewrite relations in table_name to target, with rows values."""
+        self.exec(f'DELETE FROM {table_name} WHERE {key} = ?', (target,))
+        for row in rows:
+            values = tuple([target] + row)
+            q_marks = self.__class__.q_marks_from_values(values)
+            self.exec(f'INSERT INTO {table_name} VALUES {q_marks}', values)
+
+    @staticmethod
+    def q_marks_from_values(values: tuple[Any]) -> str:
+        """Return placeholder to insert values into SQL code."""
+        return '(' + ','.join(['?'] * len(values)) + ')'
+
+
+class BaseModel:
+    """Template for most of the models we use/derive from the DB."""
+    table_name = ''
+    to_save: list[str] = []
+    id_: None | int | str
+    id_type: type[Any] = int
+
+    @classmethod
+    def from_table_row(cls, db_conn: DatabaseConnection,
+                       row: Row | list[Any]) -> Any:
+        """Make from DB row, write to DB cache."""
+        obj = cls(*row)
+        assert isinstance(obj.id_, cls.id_type)
+        cache = getattr(db_conn, f'cached_{cls.table_name}')
+        cache[obj.id_] = obj
+        return obj
+
+    @classmethod
+    def _by_id(cls,
+               db_conn: DatabaseConnection,
+               id_: int | str) -> tuple[Any, bool]:
+        """Return instance found by ID, or None, and if from cache or not."""
+        from_cache = False
+        obj = None
+        cache = getattr(db_conn, f'cached_{cls.table_name}')
+        if id_ in cache.keys():
+            obj = cache[id_]
+            from_cache = True
+        else:
+            for row in db_conn.exec(f'SELECT * FROM {cls.table_name} '
+                                    'WHERE id = ?', (id_,)):
+                obj = cls.from_table_row(db_conn, row)
+                cache[id_] = obj
+                break
+        return obj, from_cache
+
+    def set_int_id(self, id_: int | None) -> None:
+        """Set id_ if >= 1 or None, else fail."""
+        if (id_ is not None) and id_ < 1:
+            msg = f'illegal {self.__class__.__name__} ID, must be >=1: {id_}'
+            raise HandledException(msg)
+        self.id_ = id_
+
+    def save_core(self, db_conn: DatabaseConnection,
+                  update_with_lastrowid: bool = True) -> None:
+        """Write bare-bones self (sans connected items), ensuring self.id_."""
+        values = tuple([self.id_] + [getattr(self, key)
+                                     for key in self.to_save])
+        q_marks = DatabaseConnection.q_marks_from_values(values)
+        table_name = self.table_name
+        cursor = db_conn.exec(f'REPLACE INTO {table_name} VALUES {q_marks}',
+                              values)
+        if update_with_lastrowid:
+            self.id_ = cursor.lastrowid
+        cache = getattr(db_conn, f'cached_{table_name}')
+        cache[self.id_] = self