Re: [sqlalchemy] ORM and objects with properties that need conversion to write to database
Thank you, that looks like what I was looking for but didn't know what it was called. On 10/8/20 4:55 AM, Simon King wrote: > On Thu, Oct 8, 2020 at 3:38 AM Richard Damon wrote: >> I am working on a app using SQLAlchemy's ORM layer to interface to the >> database, but I am running into an issue that if an object has >> 'complicated' property, like a UUID, that SQLAlchemy doesn't know how to >> handle. One option would be to make the propery actually only hold a >> database suitable representation, and I see an option to add a >> 'reconstructor' to convert a value read from the database into an >> object. Is there a similar way that when writing the object, to indicate >> how to convert the object into a format that can be put into the database? >> > The usual pattern is to create a custom datatype using > sqlalchemy.types.TypeDecorator. You would override the > process_bind_baram and process_result_value methods to convert objects > between the python and database representations: > > https://docs.sqlalchemy.org/en/13/core/custom_types.html#augmenting-existing-types > > For the specific case of UUIDs, there is an example in the docs that > will use Postgres' UUID type against postgres, and CHAR against other > databases: > > https://docs.sqlalchemy.org/en/13/core/custom_types.html#backend-agnostic-guid-type > > Hope that helps, > > Simon > -- Richard Damon -- 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/9a984aed-26d1-5c13-d1b5-05529e58b2db%40Damon-Family.org.
Re: [sqlalchemy] ORM and objects with properties that need conversion to write to database
On Thu, Oct 8, 2020 at 3:38 AM Richard Damon wrote: > > I am working on a app using SQLAlchemy's ORM layer to interface to the > database, but I am running into an issue that if an object has > 'complicated' property, like a UUID, that SQLAlchemy doesn't know how to > handle. One option would be to make the propery actually only hold a > database suitable representation, and I see an option to add a > 'reconstructor' to convert a value read from the database into an > object. Is there a similar way that when writing the object, to indicate > how to convert the object into a format that can be put into the database? > The usual pattern is to create a custom datatype using sqlalchemy.types.TypeDecorator. You would override the process_bind_baram and process_result_value methods to convert objects between the python and database representations: https://docs.sqlalchemy.org/en/13/core/custom_types.html#augmenting-existing-types For the specific case of UUIDs, there is an example in the docs that will use Postgres' UUID type against postgres, and CHAR against other databases: https://docs.sqlalchemy.org/en/13/core/custom_types.html#backend-agnostic-guid-type Hope that helps, Simon -- 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/CAFHwexeVbT%3DAN%2BBTxNVoMY0PY3U7rTK73d1XHcbZYM%2BkQpp1RA%40mail.gmail.com.
[sqlalchemy] ORM and objects with properties that need conversion to write to database
I am working on a app using SQLAlchemy's ORM layer to interface to the database, but I am running into an issue that if an object has 'complicated' property, like a UUID, that SQLAlchemy doesn't know how to handle. One option would be to make the propery actually only hold a database suitable representation, and I see an option to add a 'reconstructor' to convert a value read from the database into an object. Is there a similar way that when writing the object, to indicate how to convert the object into a format that can be put into the database? -- Richard Damon -- 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/a67e28b7-cd9e-174d-2f6e-cd38c9122f7d%40Damon-Family.org.
