Add field option for fetch_from

README.md

@@ -62,10 +62,11 @@ inserted onto the system.
 > :warning: **Limitation! Fetch can only fetch limited classes correctly**: int, float and str!
 
 Finally, you may wish to recreate objects from a table that already exist, for
-this purpose we have the function `fetch_from(class_, object_id)` as well
+this purpose we have the function `fetch_from(class_, value, field)` as well
 as `is_fetchable(className, object_id)` former fetches a record from the
-SQL database whereas the latter checks if it is fetchable (most likely
-to check if it exists.)
+SQL database given a field and value. If only the value is provided,
+ field defaults to 'obj_id' which is unique for all objects,
+ whereas the latter checks if it is fetchable (most likely to check if it exists.)
 
 ```python
 >>> fetch_from(Student, 2)

datalite/__init__.py

@@ -171,21 +171,19 @@ def _get_table_cols(cur: sql.Cursor, table_name: str) -> List[str]:
     return [row_info[1] for row_info in cur.fetchall()][1:]
 
 
-def fetch_from(class_: type, obj_id: int) -> Any:
+def fetch_from(class_: type, value: Any, field: str = 'obj_id') -> Any:
     """
     Fetch a class_ type variable from its bound db.
     :param class_: Class to fetch.
-    :param obj_id: Unique object id of the class.
+    :param field: Field to check for, by default, object id.
+    :param value: Value of the field to check for.
     :return: The object whose data is taken from the database.
     """
     table_name = class_.__name__.lower()
-    if not is_fetchable(class_, obj_id):
-        raise KeyError(f"An object with the id {obj_id} in table {table_name} does not exist."
-                       f"or is otherwise unable to be fetched.")
     with sql.connect(getattr(class_, 'db_path')) as con:
         cur: sql.Cursor = con.cursor()
-        cur.execute(f"SELECT * FROM {class_.__name__.lower()} WHERE obj_id = {obj_id};")  # Guaranteed to work.
-        field_values: List[str] = list(cur.fetchone())[1:]
+        cur.execute(f"SELECT * FROM {table_name} WHERE {field} = {_convert_sql_format(value)};")
+        obj_id, *field_values = list(cur.fetchone())
         field_names: List[str] = _get_table_cols(cur, class_.__name__.lower())
     kwargs = dict(zip(field_names, field_values))
     obj = class_(**kwargs)

setup.py

@@ -5,7 +5,7 @@ with open("README.md", "r") as fh:
 
 setuptools.setup(
     name="datalite", # Replace with your own username
-    version="0.4.1",
+    version="0.4.2",
     author="Ege Ozkan",
     author_email="egeemirozkan24@gmail.com",
     description="A small package that binds dataclasses to an sqlite database",
@@ -14,9 +14,9 @@ setuptools.setup(
     url="https://github.com/ambertide/datalite",
     packages=setuptools.find_packages(),
     classifiers=[
-        "Programming Language :: Python :: 3",
+        "Programming Language :: Python :: 3.7",
         "License :: OSI Approved :: MIT License",
         "Operating System :: OS Independent",
     ],
-    python_requires='>=3.6',
+    python_requires='>=3.7',
 )

test/main_tests.py

@@ -82,6 +82,10 @@ class DatabaseFetchCalls(unittest.TestCase):
         t_obj = fetch_from(FetchClass, self.objs[0].obj_id)
         self.assertEqual(self.objs[0], t_obj)
 
+    def testFetchFromDif(self):
+        t_obj = fetch_from(FetchClass, self.objs[0].str_, 'str_')
+        self.assertEqual(self.objs[0], t_obj)
+
     def testFetchAll(self):
         t_objs = fetch_all(FetchClass)
         self.assertEqual(tuple(self.objs), t_objs)
@@ -97,5 +101,6 @@ class DatabaseFetchCalls(unittest.TestCase):
     def tearDown(self) -> None:
         [obj.remove_entry() for obj in self.objs]
 
+
 if __name__ == '__main__':
     unittest.main()