Add f key on delete cascading (#64)

* Added ondelete argument to ForeignKey to allow cascading deletion if foreign model matching key is removed

* Added SQLiteConnection connection factory to sqlite connections to support pragma f-key constraint handling

* added foreign key delete cascading to test models & tests

* Added Parent, Child tables to database_with_cache fixture

* Added pydantic versioning limit

* added pydantic max version limit

* Added ondelete CASCADE example with ForeignKey usage

---------

Co-authored-by: Joshua (codemation) <[email protected]>

docs/model-usage.md

@@ -356,7 +356,7 @@ class EmployeeInfo(DataBaseModel):
 class Employee(DataBaseModel):
     __tablename__ = "employee" # instead of Employee
     employee_id: str = PrimaryKey()
-    emp_ssn: Optional[int] = ForeignKey(EmployeeInfo, 'ssn')
+    emp_ssn: Optional[int] = ForeignKey(EmployeeInfo, 'ssn', ondelete="CASCADE")
     employee_info: Optional[EmployeeInfo] = Relationship("EmployeeInfo", 'employee_id', 'bio_id')
     position: List[Optional[Positions]] = []
     salary: float

pydbantic/core.py

@@ -151,12 +151,20 @@ def PrimaryKey(
 
 
 def ForeignKey(
-    foreign_model: Union[T, str], foreign_model_key: str, default=None
+    foreign_model: Union[T, str],
+    foreign_model_key: str,
+    default=None,
+    ondelete: Optional[str] = None,
 ) -> Any:
+    """
+    ondelete:
+        "CASCADE"
+    """
     return get_field_config(
         foreign_model=foreign_model,
         foreign_model_key=foreign_model_key,
         default=default,
+        foreign_model_ondelete=ondelete,
     )
 
 
@@ -205,6 +213,7 @@ def get_field_config(
     autoincrement: Optional[bool] = None,
     foreign_model: Any = None,
     foreign_model_key: Optional[str] = None,
+    foreign_model_ondelete: Optional[str] = None,
     relationship_model: Optional[str] = None,
     relationship_local_column: Optional[str] = None,
     relationship_model_column: Optional[str] = None,
@@ -227,6 +236,8 @@ def get_field_config(
     if foreign_model is not None:
         config["foreign_model"] = foreign_model
         config["foreign_model_key"] = foreign_model_key
+        if foreign_model_ondelete is not None:
+            config["ondelete"] = foreign_model_ondelete
     if relationship_model is not None:
         config["relationship_model"] = relationship_model
         config["relationship_local_column"] = relationship_local_column
@@ -761,12 +772,16 @@ def convert_fields_to_columns(
                     if "foreign_model_key" not in config
                     else config["foreign_model_key"]
                 )
-
+                ondelete_config = {}
+                if "ondelete" in config:
+                    ondelete_config["ondelete"] = config["ondelete"]
                 # foreign_model_sqlalchemy_type = cls.__metadata__.tables[foreign_model_name]['column_map'][foreign_model_key][0]
                 # sqlalchemy_type_config[field_property] = foreign_model_sqlalchemy_type
 
                 field_constraints[field_property].append(
-                    sqlalchemy.ForeignKey(f"{foreign_table_name}.{foreign_model_key}")
+                    sqlalchemy.ForeignKey(
+                        f"{foreign_table_name}.{foreign_model_key}", **ondelete_config
+                    )
                 )
             if "relationship_model" in config:
                 relationship_definitions[config["relationship_model"]] = {

pydbantic/database.py

@@ -1,5 +1,6 @@
 import asyncio
 import logging
+import sqlite3
 import time
 import uuid
 from copy import deepcopy
@@ -11,13 +12,20 @@
 from alembic.migration import MigrationContext
 from alembic.operations import Operations
 from databases import Database as _Database
+from databases import backends
 from sqlalchemy import create_engine
 
 from pydbantic.cache import Redis
 from pydbantic.core import BaseMeta, DatabaseInit, DataBaseModel, TableMeta
 from pydbantic.translations import DEFAULT_TRANSLATIONS
 
 
+class SQLiteConnection(sqlite3.Connection):
+    def __init__(self, *args, **kwargs):
+        super().__init__(*args, **kwargs)
+        self.execute("pragma foreign_keys=1")
+
+
 class Database:
     def __init__(
         self,
@@ -679,7 +687,11 @@ async def _migrate(self):
         return self
 
     async def db_connection(self):
-        async with _Database(self.DB_URL) as connection:
+        conn_factory = (
+            {"factory": SQLiteConnection} if "sqlite" in self.DB_URL.lower() else {}
+        )
+
+        async with _Database(self.DB_URL, **conn_factory) as connection:
             while True:
                 status = yield connection
                 if status == "finished":

requirements.txt

@@ -1,7 +1,7 @@
 SQLAlchemy==1.4.28
 databases==0.6.0
 redis>=4.2.0
-pydantic>=1.9.1
+pydantic>=1.9.1,<2
 asyncpg==0.24.0
 aiosqlite==0.17.0
 alembic==1.8.1

setup.py

@@ -4,7 +4,7 @@
     "SQLAlchemy==1.4.28",
     "databases==0.5.3",
     "redis>=4.2.0",
-    "pydantic>=1.9.1",
+    "pydantic>=1.9.1,pydantic<2",
     "alembic==1.8.1",
 ]
 MYSQL_REQUIREMENTS = [

tests/conftest.py

@@ -8,7 +8,7 @@
 
 from pydbantic import Database
 from pydbantic.cache import Redis
-from tests.models import Department, Employee, EmployeeInfo, Positions
+from tests.models import Child, Department, Employee, EmployeeInfo, Parent, Positions
 
 DB_PATH = {
     "sqlite": "sqlite:///test.db",
@@ -52,7 +52,7 @@ async def database_with_cache(request):
 
     db = await Database.create(
         request.param,
-        tables=[EmployeeInfo, Employee, Positions, Department],
+        tables=[EmployeeInfo, Employee, Positions, Department, Parent, Child],
         cache_enabled=False,
         testing=True,
     )

tests/models/__init__.py

@@ -11,6 +11,16 @@ def uuid_str():
     return str(uuid4())
 
 
+class Parent(DataBaseModel):
+    name: str = PrimaryKey()
+    sex: str
+
+
+class Child(DataBaseModel):
+    name: str = PrimaryKey()
+    parent: str = ForeignKey(Parent, foreign_model_key="name", ondelete="CASCADE")
+
+
 class Department(DataBaseModel):
     department_id: str = PrimaryKey()
     name: str

tests/test_models.py

@@ -1,7 +1,7 @@
 import pytest
 
 from pydbantic import Database
-from tests.models import Employee
+from tests.models import Child, Employee, Parent
 
 
 @pytest.mark.asyncio
@@ -53,3 +53,14 @@ async def test_models(database_with_cache):
     assert result[0].position[0].name == employee.position[0].name
     assert result[0].salary == employee.salary
     assert result[0].is_employed == employee.is_employed
+
+    parent = await Parent.create(name="bob", sex="MALE")
+    child = await Child.create(name="joe", parent=parent.name)
+
+    assert await Parent.all()
+    assert await Child.all()
+
+    await parent.delete()
+
+    assert not await Parent.all()
+    assert not await Child.all()