Hide (almost all) remaining SQL code in DB module.

[plomtask] / plomtask / db.py

diff --git a/plomtask/db.py b/plomtask/db.py
index 01bc3e940767eafcd7a3e728a5d73caf7b04aa79..848e750f1a3feccc3d9fb75c192c47a0a4edd4de 100644 (file)
--- a/plomtask/db.py
+++ b/plomtask/db.py
@@ -1,7 +1,7 @@
 """Database management."""
 from os.path import isfile
 from difflib import Differ
-from sqlite3 import connect as sql_connect, Cursor
+from sqlite3 import connect as sql_connect, Cursor, Row
 from typing import Any, Dict
 from plomtask.exceptions import HandledException
 
@@ -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()
@@ -53,6 +53,7 @@ class DatabaseConnection:
         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."""
@@ -65,3 +66,96 @@ 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)) + ')'
+
+
+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.row_where(cls.table_name, '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