one to many orm

Steven Chen · Steven Chen · commit f7b771ad119f · 2023-11-10T01:18:16.000-08:00
diff --git a/10_one_to_many_orm/__init__.py b/10_one_to_many_orm/__init__.py
diff --git a/10_one_to_many_orm/db_init.py b/10_one_to_many_orm/db_init.py
@@ -0,0 +1,46 @@
+import datetime
+
+from sqlalchemy import create_engine, String, ForeignKey
+from sqlalchemy.ext.declarative import declarative_base
+from sqlalchemy.orm import sessionmaker, Mapped, mapped_column, relationship
+from typing_extensions import Annotated
+from typing import List
+
+
+engine = create_engine('mysql://root:test@localhost/testdb', echo=True)
+Base = declarative_base()
+
+
+int_pk = Annotated[int, mapped_column(primary_key=True)]
+required_unique_name = Annotated[str, mapped_column(String(128), unique=True, nullable=False)]
+timestamp_not_null = Annotated[datetime.datetime, mapped_column(nullable=False)]
+
+
+class Department(Base):
+    __tablename__ = "department"
+
+    id: Mapped[int_pk]
+    name: Mapped[required_unique_name]
+
+    employees: Mapped[List["Employee"]] = relationship(back_populates="department")
+
+    def __repr__(self):
+        return f'id: {self.id}, name: {self.name}'
+
+
+class Employee(Base):
+    __tablename__ = "employee"
+
+    id: Mapped[int_pk]
+    dep_id: Mapped[int] = mapped_column(ForeignKey("department.id"))
+    name: Mapped[required_unique_name]
+    birthday: Mapped[timestamp_not_null]
+
+    department: Mapped[Department] = relationship(lazy=False, back_populates="employees")
+
+    def __repr__(self):
+        return f'id: {self.id}, dep_id: {self.dep_id}, name: {self.name}, birthday: {self.birthday}'
+
+
+Base.metadata.create_all(engine)
+Session = sessionmaker(bind=engine)
diff --git a/10_one_to_many_orm/query.py b/10_one_to_many_orm/query.py
@@ -0,0 +1,30 @@
+from db_init import Session, Department, Employee
+
+
+def insert_records(session):
+    d1 = Department(name="hr")
+    e1 = Employee(department=d1, name="Jack", birthday="2000-10-1")
+    session.add(e1)
+
+    session.commit()
+
+
+def select_employee(session):
+    emp = session.query(Employee).filter(Employee.id == 1).one()
+
+    print(emp)
+    print(emp.department)
+
+
+def select_department(session):
+    dep = session.query(Department).filter(Department.id == 1).one()
+
+    print(dep)
+    print(dep.employees)
+
+
+session = Session()
+
+# insert_records(session)
+# select_employee(session)
+select_department(session)
