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Is it possible to use SQLAlchemy mappers (or similar)? #238
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[-]Is it possible to use SQLAlchemy mappers?[/-][+]Is it possible to use SQLAlchemy mappers (or similar)?[/+]on Aug 20, 2020 Try pydantic. Parsing list of db rows would be look like this:
from typing import List from pydantic import BaseModel class Note(BaseModel): a: int b: str # rows from database provide dict-like interface x: List[dict] = [dict(a=1, b="2"), dict(a=3, b="4")] y: List[Note] = [Note.parse_obj(i) for i in x] print(y)
Output:
[Note(a=1, b='2'), Note(a=3, b='4')]Pydantic also allows to parse complicated and nested dictionaries to objects and supports type hinting (if you use IDE, eg PyCharm).
I can share my workaround for this. Hope this will be helpful.
notes = sqlalchemy.Table( "notes", metadata, sqlalchemy.Column("id", sqlalchemy.Integer, primary_key=True), sqlalchemy.Column("text", sqlalchemy.String(length=100)), sqlalchemy.Column("completed", sqlalchemy.Boolean), ) from dataclasses import dataclass, fields @dataclass class DBModel: __table__ = None @classmethod def from_db(cls, record): d = {} for field in fields(cls): d.update({field.name: record[cls.__table__.c[field.name]]}) # If we use outerjoin and corresponding record not exist if d['id'] is None: return None return cls(**d) @dataclass class Note: id: int text: str completed: bool __table__ = notes
Now you can convert your Record object into Note object
rows = await databse.fetch_all(select([notes])) for row in rows: note = Note.from_db(row)
sqlalchemy 1.4 supports the full ORM when used with asyncio: https://docs.sqlalchemy.org/en/14/orm/extensions/asyncio.html#synopsis-orm
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on Apr 1, 2021
Is there a way to automatically map a result row from a query to a class, something like SQLAlchemy's mappers, e.g.:
For simple cases like the above I can do the mapping myself fairly easily but for complicated joins the code becomes ugly and repetitive.
For clarity, I don't want/or need a full ORM, I just want to map the database rows to some data classes for ease of use elsewhere.