Re: [sqlalchemy] Usage of sqlalchemy Uuid type in declarative mapping
You are fing awesome Mike.
Thanks for the answer and the links, I will dive into it tomorrow first
thing in the morning.
Le jeu. 6 juil. 2023 à 19:27, Mike Bayer <
mike_not_on_goo...@zzzcomputing.com> a écrit :
>
>
> On Thu, Jul 6, 2023, at 1:21 PM, Pierre Massé wrote:
>
> Dear all,
>
> I am currently working on implementing UUID as primary keys in my database.
>
> I have come across an issue that I cannot find an explanation for: using
> the `sqlalchemy.Uuid` type in declarative mapping yields different results
> at initialization. I sometimes get the following error:
>
> *"The type provided inside the 'id' attribute Mapped annotation is the
> SQLAlchemy type . Expected a Python
> type instead"*
>
>
> this message is referring to the difference between *Python* types and
> *SQLAlchemy* types. A SQLAlchemy type is like "sqlalchemy.Uuid" as you are
> using. The Python type is the Python UUID type:
> https://docs.python.org/3/library/uuid.html#uuid.UUID
>
> the default lookup is documented here:
> https://docs.sqlalchemy.org/en/20/orm/declarative_tables.html#mapped-column-derives-the-datatype-and-nullability-from-the-mapped-annotation
>
> so you would want
>
> import uuid
>
> class XYZ(...):
> # ...
>
>id: Mapped[uuid.UUID] = mapped_column(...)
>
>
>
>
>
>
>
>
> I have a Caregiver table, for which id is a PostgreSQL UUID, and a Match
> Event table holding 2 fields which use the Caregiver id as foreign key.
> Those 2 fields are PostgreSQL UUID as well.
>
> If my classes definitions are as follow, the initialization runs smoothly,
> as well as inserts in the Match Event table:
>
> from sqlalchemy import (
> ForeignKey,
> Uuid,
> )
> from sqlalchemy.orm import (
> Mapped,
> mapped_column,
> relationship,
> )
>
> class MatchEventOrm(Base):
> __tablename__ = "match_event"
>
> id: Mapped[int] = mapped_column(primary_key=True)
> subject_caregiver_id: Mapped[Uuid] = mapped_column(
> ForeignKey("caregiver.id")
> )
> object_caregiver_id: Mapped[Uuid] = mapped_column(
> ForeignKey("caregiver.id")
> )
> subject_caregiver: Mapped["CaregiverOrm"] = relationship(
> back_populates="match_event_subject_of",
> foreign_keys=[subject_caregiver_id],
> )
> object_caregiver: Mapped["CaregiverOrm"] = relationship(
> back_populates="match_event_object_of",
> foreign_keys=[object_caregiver_id],
> )
>
> class CaregiverOrm(Base):
> __tablename__ = "caregiver"
>
> id: Mapped[*str*] = mapped_column(primary_key=True)
> uid: Mapped[str]
> user_email: Mapped[str]
>
> ...
>
>
>
> However, if I change to the following:
> from sqlalchemy import (
> ForeignKey,
> Uuid,
> )
> from sqlalchemy.orm import (
> Mapped,
> mapped_column,
> relationship,
> )
>
> class MatchEventOrm(Base):
> __tablename__ = "match_event"
>
> id: Mapped[int] = mapped_column(primary_key=True)
> subject_caregiver_id: Mapped[Uuid] = mapped_column(
> ForeignKey("caregiver.id")
> )
> object_caregiver_id: Mapped[Uuid] = mapped_column(
> ForeignKey("caregiver.id")
> )
> subject_caregiver: Mapped["CaregiverOrm"] = relationship(
> back_populates="match_event_subject_of",
> foreign_keys=[subject_caregiver_id],
> )
> object_caregiver: Mapped["CaregiverOrm"] = relationship(
> back_populates="match_event_object_of",
> foreign_keys=[object_caregiver_id],
> )
>
> class CaregiverOrm(Base):
> __tablename__ = "caregiver"
>
> id: Mapped[*Uuid*] = mapped_column(primary_key=True)
> uid: Mapped[str]
> user_email: Mapped[str]
>
> ...
>
>
> I get the aforementioned error message.
>
> I may be using type annotations wrong, any insight on what I am doing
> wrong would be welcome.
>
> Thanks a lot for your support.
>
> Regards,
>
> Pierre
>
>
>
> --
> SQLAlchemy -
> The Python SQL Toolkit and Object Relational Mapper
>
> http://www.sqlalchemy.org/
>
> To post example code, please provide an MCVE: Minimal, Complete, and
> Verifiable Example. See http://stackoverflow.com/help/mcve for a full
> description.
> ---
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> To view this discussion on the web visit
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>
> .
>
>
> --
> SQLAlchemy -
> The Python SQL Toolkit and Object Relational Mapper
>
> http://www.sqlalchemy.org/
>
> To post example code, please provide an MCVE: Minimal, Complete, and
> Verifiable Example. See http://stackoverflow.com/help/mcve for a full
> description.
> ---
> You received this message because you are subscribed to the Google Groups
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> To view this discussion on the web visit
>
Re: [sqlalchemy] Usage of sqlalchemy Uuid type in declarative mapping
On Thu, Jul 6, 2023, at 1:21 PM, Pierre Massé wrote:
> Dear all,
>
> I am currently working on implementing UUID as primary keys in my database.
>
> I have come across an issue that I cannot find an explanation for: using the
> `sqlalchemy.Uuid` type in declarative mapping yields different results at
> initialization. I sometimes get the following error:
>
> *"The type provided inside the 'id' attribute Mapped annotation is the
> SQLAlchemy type . Expected a Python
> type instead"*
this message is referring to the difference between *Python* types and
*SQLAlchemy* types. A SQLAlchemy type is like "sqlalchemy.Uuid" as you are
using. The Python type is the Python UUID type:
https://docs.python.org/3/library/uuid.html#uuid.UUID
the default lookup is documented here:
https://docs.sqlalchemy.org/en/20/orm/declarative_tables.html#mapped-column-derives-the-datatype-and-nullability-from-the-mapped-annotation
so you would want
import uuid
class XYZ(...):
# ...
id: Mapped[uuid.UUID] = mapped_column(...)
>
> I have a Caregiver table, for which id is a PostgreSQL UUID, and a Match
> Event table holding 2 fields which use the Caregiver id as foreign key. Those
> 2 fields are PostgreSQL UUID as well.
>
> If my classes definitions are as follow, the initialization runs smoothly, as
> well as inserts in the Match Event table:
>
> from sqlalchemy import (
> ForeignKey,
> Uuid,
> )
> from sqlalchemy.orm import (
> Mapped,
> mapped_column,
> relationship,
> )
>
> class MatchEventOrm(Base):
> __tablename__ = "match_event"
>
> id: Mapped[int] = mapped_column(primary_key=True)
> subject_caregiver_id: Mapped[Uuid] = mapped_column(
> ForeignKey("caregiver.id")
> )
> object_caregiver_id: Mapped[Uuid] = mapped_column(
> ForeignKey("caregiver.id")
> )
> subject_caregiver: Mapped["CaregiverOrm"] = relationship(
> back_populates="match_event_subject_of",
> foreign_keys=[subject_caregiver_id],
> )
> object_caregiver: Mapped["CaregiverOrm"] = relationship(
> back_populates="match_event_object_of",
> foreign_keys=[object_caregiver_id],
> )
>
> class CaregiverOrm(Base):
> __tablename__ = "caregiver"
>
> id: Mapped[*str*] = mapped_column(primary_key=True)
> uid: Mapped[str]
> user_email: Mapped[str]
>
> ...
>
>
>
> However, if I change to the following:
> from sqlalchemy import (
> ForeignKey,
> Uuid,
> )
> from sqlalchemy.orm import (
> Mapped,
> mapped_column,
> relationship,
> )
>
> class MatchEventOrm(Base):
> __tablename__ = "match_event"
>
> id: Mapped[int] = mapped_column(primary_key=True)
> subject_caregiver_id: Mapped[Uuid] = mapped_column(
> ForeignKey("caregiver.id")
> )
> object_caregiver_id: Mapped[Uuid] = mapped_column(
> ForeignKey("caregiver.id")
> )
> subject_caregiver: Mapped["CaregiverOrm"] = relationship(
> back_populates="match_event_subject_of",
> foreign_keys=[subject_caregiver_id],
> )
> object_caregiver: Mapped["CaregiverOrm"] = relationship(
> back_populates="match_event_object_of",
> foreign_keys=[object_caregiver_id],
> )
>
> class CaregiverOrm(Base):
> __tablename__ = "caregiver"
>
> id: Mapped[*Uuid*] = mapped_column(primary_key=True)
> uid: Mapped[str]
> user_email: Mapped[str]
>
> ...
>
>
> I get the aforementioned error message.
>
> I may be using type annotations wrong, any insight on what I am doing wrong
> would be welcome.
>
> Thanks a lot for your support.
>
> Regards,
>
> Pierre
>
>
>
>
> --
> SQLAlchemy -
> The Python SQL Toolkit and Object Relational Mapper
>
> http://www.sqlalchemy.org/
>
> To post example code, please provide an MCVE: Minimal, Complete, and
> Verifiable Example. See http://stackoverflow.com/help/mcve for a full
> description.
> ---
> You received this message because you are subscribed to the Google Groups
> "sqlalchemy" group.
> To unsubscribe from this group and stop receiving emails from it, send an
> email to sqlalchemy+unsubscr...@googlegroups.com.
> To view this discussion on the web visit
> https://groups.google.com/d/msgid/sqlalchemy/CAH4TWVuadpW3d5%3Dt3pgs8DU55Wpx%3DVGBajBKQiskzc87f-aiMw%40mail.gmail.com
>
> .
--
SQLAlchemy -
The Python SQL Toolkit and Object Relational Mapper
http://www.sqlalchemy.org/
To post example code, please provide an MCVE: Minimal, Complete, and Verifiable
Example. See http://stackoverflow.com/help/mcve for a full description.
---
You received this message because you are subscribed to the Google Groups
"sqlalchemy" group.
To unsubscribe from this group and stop receiving emails from it, send an email
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