hey there - a list[str] can be lots of different kinds of datatype, like JSON, custom array types, and PG ARRAY, which is specific to PostgreSQL. so for non-obvious datatypes like this you indicate them explicitly:
from sqlalchemy.dialects.postgresql import ARRAY from sqlalchemy import String col: Mapped[list[str]] = mapped_column(ARRAY(String)) hoping this is clear from the doc at https://docs.sqlalchemy.org/en/20/orm/declarative_tables.html#using-annotated-declarative-table-type-annotated-forms-for-mapped-column which illustrates several of the mapped_column() with explicit datatype and also states "If the `mapped_column()` <https://docs.sqlalchemy.org/en/20/orm/mapping_api.html#sqlalchemy.orm.mapped_column> construct indicates an explicit type as passed to the `mapped_column.__type` <https://docs.sqlalchemy.org/en/20/orm/mapping_api.html#sqlalchemy.orm.mapped_column.params.__type> argument, then the given Python type is disregarded". On Sun, Feb 19, 2023, at 7:21 PM, Samuel Killin wrote: > I'm struggling to define a SQLAlchemy column for a postgres string array > using the new declarative mapping pattern in 2.0. > > I would expect something like this to work: > *my_col: Mapped[list[str]] = mapped_column()* > > However, this throws with: > *sqlalchemy.exc.ArgumentError: Could not locate SQLAlchemy Core type for > Python type list[str] inside the 'my_col' attribute Mapped annotation * > Any ideas? > > > -- > 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/3b0e17b9-15cc-43b8-9c3c-e3ce73c71c85n%40googlegroups.com > > <https://groups.google.com/d/msgid/sqlalchemy/3b0e17b9-15cc-43b8-9c3c-e3ce73c71c85n%40googlegroups.com?utm_medium=email&utm_source=footer>. -- 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/ef087ba8-bd2c-4524-84ad-31aededf1cba%40app.fastmail.com.
