X-Git-Url: https://plomlompom.com/repos/berlin_corona.txt?a=blobdiff_plain;f=plomtask%2Fdb.py;h=bf2b79f758b313525816581620a792330fdbd9a2;hb=23c7ff7f9833ff5b0e547c19a4ad85325a5d3400;hp=f53a94c4f085f3664d66f0b0cc38863b217741e1;hpb=56b8aa166d51d139edb41f0ef250b1854a5e93e8;p=plomtask

diff --git a/plomtask/db.py b/plomtask/db.py
index f53a94c..bf2b79f 100644
--- a/plomtask/db.py
+++ b/plomtask/db.py
@@ -1,11 +1,13 @@
 """Database management."""
+from __future__ import annotations
 from os.path import isfile
 from difflib import Differ
-from sqlite3 import connect as sql_connect, Cursor
-from typing import Any, Dict
+from sqlite3 import connect as sql_connect, Cursor, Row
+from typing import Any, Self, TypeVar, Generic
 from plomtask.exceptions import HandledException
 
 PATH_DB_SCHEMA = 'scripts/init.sql'
+EXPECTED_DB_VERSION = 0
 
 
 class DatabaseFile:  # pylint: disable=too-few-public-methods
@@ -23,11 +25,22 @@ 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 DB version and schema."""
         self.exists = isfile(self.path)
         if self.exists:
+            self._validate_user_version()
             self._validate_schema()
 
+    def _validate_user_version(self) -> None:
+        """Compare DB user_version with EXPECTED_DB_VERSION."""
+        sql_for_db_version = 'PRAGMA user_version'
+        with sql_connect(self.path) as conn:
+            db_version = list(conn.execute(sql_for_db_version))[0][0]
+            if db_version != EXPECTED_DB_VERSION:
+                msg = f'Wrong DB version, expected '\
+                        f'{EXPECTED_DB_VERSION}, got {db_version}.'
+                raise HandledException(msg)
+
     def _validate_schema(self) -> None:
         """Compare found schema with what's stored at PATH_DB_SCHEMA."""
         sql_for_schema = 'SELECT sql FROM sqlite_master ORDER BY sql'
@@ -49,11 +62,6 @@ 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."""
@@ -66,3 +74,124 @@ 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.delete_where(table_name, 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)
+
+    def row_where(self, table_name: str, key: str,
+                  target: int | str) -> list[Row]:
+        """Return list of Rows at table where key == target."""
+        return list(self.exec(f'SELECT * FROM {table_name} WHERE {key} = ?',
+                              (target,)))
+
+    def column_where(self, table_name: str, column: str, key: str,
+                     target: int | str) -> list[Any]:
+        """Return column of table where key == target."""
+        return [row[0] for row in
+                self.exec(f'SELECT {column} FROM {table_name} '
+                          f'WHERE {key} = ?', (target,))]
+
+    def column_all(self, table_name: str, column: str) -> list[Any]:
+        """Return complete column of table."""
+        return [row[0] for row in
+                self.exec(f'SELECT {column} FROM {table_name}')]
+
+    def delete_where(self, table_name: str, key: str, target: int) -> None:
+        """Delete from table where key == target."""
+        self.exec(f'DELETE FROM {table_name} WHERE {key} = ?', (target,))
+
+    @staticmethod
+    def q_marks_from_values(values: tuple[Any]) -> str:
+        """Return placeholder to insert values into SQL code."""
+        return '(' + ','.join(['?'] * len(values)) + ')'
+
+
+X = TypeVar('X', int, str)
+T = TypeVar('T', bound='BaseModel[Any]')
+
+
+class BaseModel(Generic[X]):
+    """Template for most of the models we use/derive from the DB."""
+    table_name = ''
+    to_save: list[str] = []
+    id_: None | X
+    cache_: dict[X, Self] = {}
+
+    @classmethod
+    def from_table_row(cls: type[T],
+                       # pylint: disable=unused-argument
+                       db_conn: DatabaseConnection,
+                       row: Row | list[Any]) -> T:
+        """Make from DB row, write to DB cache."""
+        obj = cls(*row)
+        obj.cache()
+        return obj
+
+    @classmethod
+    def _by_id(cls,
+               db_conn: DatabaseConnection,
+               id_: X) -> tuple[Self | None, bool]:
+        """Return instance found by ID, or None, and if from cache or not."""
+        from_cache = False
+        obj = cls.get_cached(id_)
+        if obj:
+            from_cache = True
+        else:
+            for row in db_conn.row_where(cls.table_name, 'id', id_):
+                obj = cls.from_table_row(db_conn, row)
+                obj.cache()
+                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_  # type: ignore[assignment]
+
+    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  # type: ignore[assignment]
+        self.cache()
+
+    @classmethod
+    def get_cached(cls: type[T], id_: X) -> T | None:
+        """Get object of id_ from class's cache, or None if not found."""
+        # pylint: disable=consider-iterating-dictionary
+        if id_ in cls.cache_.keys():
+            obj = cls.cache_[id_]
+            assert isinstance(obj, cls)
+            return obj
+        return None
+
+    def cache(self) -> None:
+        """Update object in class's cache."""
+        if self.id_ is None:
+            raise HandledException('Cannot cache object without ID.')
+        self.__class__.cache_[self.id_] = self
+
+    def uncache(self) -> None:
+        """Remove self from cache."""
+        if self.id_ is None:
+            raise HandledException('Cannot un-cache object without ID.')
+        del self.__class__.cache_[self.id_]
+
+    @classmethod
+    def empty_cache(cls) -> None:
+        """Empty class's cache."""
+        cls.cache_ = {}