Add mass objects

datalite/__init__.py

@@ -1,2 +1,2 @@
-__all__ = ['commons', 'datalite_decorator', 'fetch', 'migrations', 'datalite', 'constraints']
+__all__ = ['commons', 'datalite_decorator', 'fetch', 'migrations', 'datalite', 'constraints', 'mass_actions']
 from .datalite_decorator import datalite

datalite/mass_actions.py

@@ -0,0 +1,62 @@
+"""
+This module includes functions to insert multiple records
+    to a bound database at one time, with one time open and closing
+    of the database file.
+"""
+from typing import TypeVar, Union, List, Tuple
+from dataclasses import asdict
+from .constraints import ConstraintFailedError
+from .commons import _convert_sql_format
+import sqlite3 as sql
+
+T = TypeVar('T')
+
+
+class MisformedCollectionError(Exception):
+    pass
+
+
+def is_homogeneous(objects: Union[List[T], Tuple[T]]) -> bool:
+    """
+    Check if all of the members a Tuple or a List
+        is of the same type.
+
+    :param objects: Tuple or list to check.
+    :return: If all of the members of the same type.
+    """
+    class_ = objects[0].__class__
+    return all([isinstance(obj, class_) for obj in objects])
+
+
+def create_many_entries(objects: Union[List[T], Tuple[T]]) -> None:
+    """
+    Insert many records corresponding to objects
+        in a tuple or a list.
+
+    :param objects: A tuple or a list of objects decorated
+        with datalite.
+    :return: None.
+    """
+    if not objects or not is_homogeneous(objects):
+        raise MisformedCollectionError("Tuple or List is empty or homogeneous.")
+    sql_queries = []
+    first_index: int = 0
+    table_name = objects[0].__class__.__name__.lower()
+    for obj in objects:
+        kv_pairs = asdict(obj).items()
+        sql_queries.append(f"INSERT INTO {table_name}(" +
+                           f"{', '.join(item[0] for item in kv_pairs)})" +
+                           f" VALUES ({', '.join(_convert_sql_format(item[1]) for item in kv_pairs)});")
+    with sql.connect(getattr(objects[0], "db_path")) as con:
+        cur: sql.Cursor = con.cursor()
+        try:
+            cur.execute(f"SELECT obj_id FROM {table_name} ORDER BY obj_id DESC LIMIT 1")
+            index_tuple = cur.fetchone()
+            if index_tuple:
+                first_index = index_tuple[0]
+            cur.executescript('\n'.join(sql_queries))
+        except sql.IntegrityError:
+            raise ConstraintFailedError
+        con.commit()
+    for i, obj in enumerate(objects):
+        setattr(obj, "obj_id", first_index + i)