Update model primary key for dynamic retrieval (#23)

* 删除、更新、查询支持主键名称非ID,从sqlalchemy 模型定义中获取主键

* custom error and update Document

* Update docs for primary key

* fix lint

Author: DavidSche

docs/advanced/primary_key.md

@@ -1,8 +1,22 @@
 !!! note 主键参数命名
 
     由于在 python 内部 id 的特殊性，我们设定 pk (参考 Django) 作为模型主键命名，所以在 crud 方法中，任何涉及到主键的地方，入参都为 `pk`
-    
+
 ```py title="e.g." hl_lines="2"
 async def delete(self, db: AsyncSession, primary_key: int) -> int:
     return self.delete_model(db, pk=primary_key)
 ```
+
+## 主键定义
+
+!!! warning 自动主键
+
+    我们在 SQLAlchemy CRUD Plus 内部通过 [inspect()](https://docs.sqlalchemy.org/en/20/core/inspection.html) 自动搜索表主键，
+    而非强制绑定主键列必须命名为 id，感谢 [@DavidSche](https://github.com/DavidSche) 提供帮助 
+
+```py title="e.g." hl_lines="4"
+class ModelIns(Base):
+    # your sqlalchemy model
+    # define your primary_key
+    custom_id: Mapped[int] = mapped_column(primary_key=True, index=True, autoincrement=True)
+```

docs/usage/delete_model.md

@@ -18,13 +18,15 @@ from pydantic import BaseModel
 
 from sqlalchemy_crud_plus import CRUDPlus
 
+from sqlalchemy import Mapped, mapped_column
 from sqlalchemy import DeclarativeBase as Base
 from sqlalchemy.ext.asyncio import AsyncSession
 
 
 class ModelIns(Base):
     # your sqlalchemy model
-    pass
+    # define your primary_key
+    custom_id: Mapped[int] = mapped_column(primary_key=True, index=True, autoincrement=True)
 
 
 class CreateIns(BaseModel):

docs/usage/select_model.md

@@ -15,13 +15,15 @@ from pydantic import BaseModel
 
 from sqlalchemy_crud_plus import CRUDPlus
 
+from sqlalchemy import Mapped, mapped_column
 from sqlalchemy import DeclarativeBase as Base
 from sqlalchemy.ext.asyncio import AsyncSession
 
 
 class ModelIns(Base):
     # your sqlalchemy model
-    pass
+    # define your primary_key
+    custom_id: Mapped[int] = mapped_column(primary_key=True, index=True, autoincrement=True)
 
 
 class CreateIns(BaseModel):
@@ -30,6 +32,6 @@ class CreateIns(BaseModel):
 
 
 class CRUDIns(CRUDPlus[ModelIns]):
-    async def create(self, db: AsyncSession, pk: int) -> ModelIns:
+    async def select(self, db: AsyncSession, pk: int) -> ModelIns:
         return await self.select_model(db, pk)
 ```

docs/usage/update_model.md

@@ -19,13 +19,15 @@ from pydantic import BaseModel
 
 from sqlalchemy_crud_plus import CRUDPlus
 
+from sqlalchemy import Mapped, mapped_column
 from sqlalchemy import DeclarativeBase as Base
 from sqlalchemy.ext.asyncio import AsyncSession
 
 
 class ModelIns(Base):
     # your sqlalchemy model
-    pass
+    # define your primary_key
+    custom_id: Mapped[int] = mapped_column(primary_key=True, index=True, autoincrement=True)
 
 
 class UpdateIns(BaseModel):

sqlalchemy_crud_plus/crud.py

@@ -2,17 +2,29 @@
 # -*- coding: utf-8 -*-
 from typing import Any, Generic, Iterable, Sequence, Type
 
-from sqlalchemy import Row, RowMapping, Select, delete, select, update
+from sqlalchemy import Row, RowMapping, Select, delete, inspect, select, update
 from sqlalchemy.ext.asyncio import AsyncSession
 
-from sqlalchemy_crud_plus.errors import MultipleResultsError
+from sqlalchemy_crud_plus.errors import CompositePrimaryKeysError, MultipleResultsError
 from sqlalchemy_crud_plus.types import CreateSchema, Model, UpdateSchema
 from sqlalchemy_crud_plus.utils import apply_sorting, count, parse_filters
 
 
 class CRUDPlus(Generic[Model]):
     def __init__(self, model: Type[Model]):
         self.model = model
+        self.primary_key = self._get_primary_key()
+
+    def _get_primary_key(self):
+        """
+        Dynamically retrieve the primary key column(s) for the model.
+        """
+        mapper = inspect(self.model)
+        primary_key = mapper.primary_key
+        if len(primary_key) == 1:
+            return primary_key[0]
+        else:
+            raise CompositePrimaryKeysError('Composite primary keys are not supported')
 
     async def create_model(
         self,
@@ -69,7 +81,7 @@ async def select_model(self, session: AsyncSession, pk: int) -> Model | None:
         :param pk: The database primary key value.
         :return:
         """
-        stmt = select(self.model).where(self.model.id == pk)
+        stmt = select(self.model).where(self.primary_key == pk)
         query = await session.execute(stmt)
         return query.scalars().first()
 
@@ -166,7 +178,7 @@ async def update_model(
             instance_data = obj
         else:
             instance_data = obj.model_dump(exclude_unset=True)
-        stmt = update(self.model).where(self.model.id == pk).values(**instance_data)
+        stmt = update(self.model).where(self.primary_key == pk).values(**instance_data)
         result = await session.execute(stmt)
         if commit:
             await session.commit()
@@ -218,7 +230,7 @@ async def delete_model(
         :param commit: If `True`, commits the transaction immediately. Default is `False`.
         :return:
         """
-        stmt = delete(self.model).where(self.model.id == pk)
+        stmt = delete(self.model).where(self.primary_key == pk)
         result = await session.execute(stmt)
         if commit:
             await session.commit()

sqlalchemy_crud_plus/errors.py

@@ -36,3 +36,10 @@ class MultipleResultsError(SQLAlchemyCRUDPlusException):
 
     def __init__(self, msg: str) -> None:
         super().__init__(msg)
+
+
+class CompositePrimaryKeysError(SQLAlchemyCRUDPlusException):
+    """Error raised when a table have Composite primary keys."""
+
+    def __init__(self, msg: str) -> None:
+        super().__init__(msg)