Add the decorator, add ignore db files

.gitignore

@@ -1 +1,2 @@
 .idea/*
+src/*.db

src/datalite.py

@@ -1,27 +1,35 @@
 from os.path import exists
+from pathlib import Path
 import sqlite3 as sql
-from dataclasses import Field, _MISSING_TYPE
-from typing import List, Dict, Optional
-
+from dataclasses import Field, _MISSING_TYPE, dataclass
+from typing import List, Dict, Optional, Callable
 
 """
 The default type table for conversion between
 Python types and SQLite3 Datatypes.
 """
-type_table: Dict[Optional[type], str] = {None: "NULL", int: "INTEGER", float: "REAL",
-                                         str: "TEXT", bytes: "BLOB"}
 
 
-def _database_exists(db_name: str) -> bool:
+
+def _database_exists(db_path: str) -> bool:
     """
     Check if a given database exists.
-    :param db_name: Name of the database, including the extension.
+    :param db_path: Relative path of the database, including the extension.
     :return: True if database exists, False otherwise.
     """
-    return exists(db_name)
+    return exists(db_path)
 
 
-def _sqlify(type_: Optional[type], type_overload: Dict[Optional[type], str]) -> str:
+def _create_db(db_path: str) -> None:
+    """
+    Create the database file.
+    :param db_path: Relative path of the database file, including the extension.
+    :return: None.
+    """
+    Path(db_path).touch()
+
+
+def _convert_type(type_: Optional[type], type_overload: Dict[Optional[type], str]) -> str:
     """
     Given a Python type, return the str name of its
     SQLlite equivalent.
@@ -29,29 +37,28 @@ def _sqlify(type_: Optional[type], type_overload: Dict[Optional[type], str]) ->
     :param type_overload: A type table to overload the custom type table.
     :return: The str name of the sql type.
     """
-    types_dict = type_table.copy()
-    types_dict.update(type_overload)
     try:
-        return types_dict[type_]
+        return type_overload[type_]
     except KeyError:
         raise TypeError("Requested type not in the default or overloaded type table.")
 
 
-def get_default(default_object: object) -> str:
+def _get_default(default_object: object, type_overload: Dict[Optional[type], str]) -> str:
     """
     Check if the field's default object is filled,
     if filled return the string to be put in the,
     database.
     :param default_object: The default field of the field.
+    :param type_overload: Type overload table.
     :return: The string to be put on the table statement,
     empty string if no string is necessary.
     """
-    if isinstance(default_object, _MISSING_TYPE):
-        return ""
-    elif isinstance(default_object, str):
+    if type(default_object) in type_overload:
+        if isinstance(default_object, str):
             return f' DEFAULT "{default_object}"'
         else:
             return f" DEFAULT {str(default_object)}"
+    return ""
 
 
 def _create_table(class_: type, cursor: sql.Cursor, type_overload: Dict[Optional[type], str]) -> None:
@@ -65,6 +72,23 @@ def _create_table(class_: type, cursor: sql.Cursor, type_overload: Dict[Optional
     """
     fields: List[Field] = [class_.__dataclass_fields__[key] for
                            key in class_.__dataclass_fields__.keys()]
-    sql_fields = ', '.join(f"{field.name} {_sqlify(field.type, type_overload)}"
-                           f"{get_default(field.default)}" for field in fields)
-    cursor.execute(f"CREATE TABLE {class_.__name__.lower} ({sql_fields})")
+    sql_fields = ', '.join(f"{field.name} {_convert_type(field.type, type_overload)}"
+                           f"{_get_default(field.default, type_overload)}" for field in fields)
+    sql_fields = "obj_id INTEGER PRIMARY KEY AUTOINCREMENT, " + sql_fields
+    cursor.execute(f"CREATE TABLE IF NOT EXISTS {class_.__name__.lower()} ({sql_fields});")
+
+
+def sqlify(db_path: str, type_overload: Optional[Dict[Optional[type], str]] = None,
+           *args, **kwargs) -> Callable:
+    def decorator(dataclass_: type, *args_i, **kwargs_i):
+        if not _database_exists(db_path):
+            _create_db(db_path)
+        type_table: Dict[Optional[type], str] = {None: "NULL", int: "INTEGER", float: "REAL",
+                                                 str: "TEXT", bytes: "BLOB"}
+        if type_overload is not None:
+            type_table.update(type_overload)
+        with sql.connect(db_path) as con:
+            cur: sql.Cursor = con.cursor()
+            _create_table(dataclass_, cur, type_table)
+        return dataclass_
+    return decorator