├── models.py
├── tables.py
├── mapper.py
└── main.py


/models.py:
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 1 | from dataclasses import dataclass
 2 | from datetime import datetime
 3 | 
 4 | 
 5 | @dataclass
 6 | class User:
 7 |     id: int | None
 8 |     username: str
 9 |     about: str | None
10 | 
11 | 
12 | @dataclass
13 | class Post:
14 |     id: int
15 |     text: str
16 | 
17 | 
18 | @dataclass
19 | class PostFull:
20 |     id: int | None
21 |     text: str
22 |     created_at: datetime
23 |     author: User
24 | 


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/tables.py:
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 1 | from sqlalchemy import Table, Column, MetaData, Integer, String, ForeignKey
 2 | 
 3 | metadata = MetaData()
 4 | 
 5 | users_table = Table(
 6 |     'users',
 7 |     metadata,
 8 |     Column('id', Integer, primary_key=True),
 9 |     Column('name', String),
10 | )
11 | 
12 | profiles_table = Table(
13 |     'profiles',
14 |     metadata,
15 |     Column('user_id', Integer, ForeignKey('users.id'), primary_key=True),  # TODO `id`
16 |     Column('about', String),
17 | )
18 | 
19 | posts_table = Table(
20 |     'posts',
21 |     metadata,
22 |     Column('id', Integer, primary_key=True),
23 |     Column('user_id', Integer, ForeignKey('users.id')),
24 |     Column('text', String),
25 |     Column('date', String),
26 | )
27 | 


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/mapper.py:
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 1 | from sqlalchemy import select, join
 2 | from sqlalchemy.orm import registry, relationship, column_property
 3 | from sqlalchemy.testing.schema import mapped_column
 4 | 
 5 | from models import User, Post, PostFull
 6 | from tables import users_table, posts_table, profiles_table, metadata
 7 | 
 8 | mapper_registry = registry(metadata=metadata)
 9 | mapper_registry.map_imperatively(Post, posts_table)
10 | mapper_registry.map_imperatively(
11 |     PostFull,
12 |     posts_table,
13 |     properties={
14 |         "user": relationship(User)
15 |     }
16 | )
17 | 
18 | users_query = join(users_table, profiles_table)
19 | mapper_registry.map_imperatively(
20 |     User,
21 |     users_query,
22 |     properties={
23 |         "username":users_table.c.name,
24 |         "id":users_table.c.id,
25 |     }
26 | )
27 | 


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/main.py:
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 1 | from datetime import datetime
 2 | 
 3 | from sqlalchemy import create_engine, select
 4 | from sqlalchemy.orm import sessionmaker
 5 | 
 6 | from mapper import mapper_registry
 7 | from models import User, PostFull, Post
 8 | 
 9 | 
10 | def main():
11 |     engine = create_engine("sqlite:///file.db", echo=True)
12 |     mapper_registry.metadata.create_all(engine)
13 | 
14 |     sm = sessionmaker(bind=engine)
15 | 
16 |     with sm() as session:
17 |         user1 = User(id=None, username="hello", about="world")
18 |         user2 = User(id=None, username="hello", about="world")
19 |         post1 = PostFull(
20 |             id=None,
21 |             text="lorem ipsum",
22 |             created_at=datetime.now(),
23 |             author=user1,
24 |         )
25 |         session.add_all([user1, user2, post1])
26 |         session.commit()
27 | 
28 |     with sm() as session:
29 |         posts = session.execute(select(Post)).all()
30 |         print(posts)
31 | 
32 | 
33 | if __name__ == "__main__":
34 |     main()
35 | 


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