background on mapping ORM classes to reflected tables is at
https://docs.sqlalchemy.org/en/14/orm/declarative_tables.html#mapping-declaratively-with-reflected-tables
and there are three general methods depending on your needs.
DeferredReflection is oriented towards explicit class setup, and automap is
oriented towards "just give me pre-made classes", with much less ability to
customize how the classes look and behave.
if you were using automap and needed to override PK for this one class:
from sqlalchemy.ext.automap import automap_base
from sqlalchemy import create_engine, Integer, Column
Base = automap_base()
class MyTable(Base):
__tablename__ = 'my_table'
userID = Column(Integer, primary_key=True)
groupID = Column(Integer, primary_key=True)
engine = create_engine("mysql://...")
# reflect the tables
Base.prepare(autoload_with=engine)
On Sun, Jul 10, 2022, at 3:12 AM, Carl Brewer wrote:
>
> I'm reflecting a table into the ORM, that has no defined unique key, but
> has two fields that when combined are unique - it's MySQL, but that
> shouldn't matter.
>
> Eg:
>
> int userID and int groupId are non-unique, but when combined they are.
>
>
> Can anyone point me at a simple example of how to do it? Everything
> I've found by searching has been a complex example, I just want to have
> the table reflected into SQLAlchemy, it's only ever going to be read-only.
>
> out of curiosity, is there a simple way to reflect an entire database,
> or do you always need to set up classes for each table?
>
> Thank you!
>
> Carl
>
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> SQLAlchemy -
> The Python SQL Toolkit and Object Relational Mapper
>
> http://www.sqlalchemy.org/
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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.
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