Is it possible to use SQLAlchemy mappers (or similar)? #238

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1. petedmarsh

   changed the title [-]Is it possible to use SQLAlchemy mappers?[/-] [+]Is it possible to use SQLAlchemy mappers (or similar)?[/+] on Aug 20, 2020
2. artslob commented on Oct 8, 2020

   

   artslob

   on Oct 8, 2020

   Last edited by artslob

   More actions

   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).
3. ikhomutov commented on Jan 6, 2021

   

   ikhomutov

   on Jan 6, 2021

   Last edited by ikhomutov

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   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)
4. graingert commented on Jan 11, 2021

   

   graingert

   on Jan 11, 2021

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   sqlalchemy 1.4 supports the full ORM when used with asyncio: https://docs.sqlalchemy.org/en/14/orm/extensions/asyncio.html#synopsis-orm
5. lovelydinosaur

   closed this as completedon Mar 25, 2021
6. lovelydinosaur

   reopened this on Mar 25, 2021
7. lovelydinosaur

   closed this as completedon Apr 1, 2021
8. encode

   locked and limited conversation to collaborators on Apr 1, 2021