SQLAlchemy has a general philosophy of fn(*args) vs fn(list):
1. if the sequence of items represents **database data**, we use a **list** or
other inline sequence. E.g. in_():
column.in_([1, 2, 3])
2. if the sequence of items represents **SQL structure**, we use a variable
length *Args. E.g. Table:
Table(name, metadata, *cols_and_other_constraints)
and_(), or(), etc:
and_(*sequence_of_expressions(
ORM query:
session.query(*sequence_of_entities_expressions_etc)
select() should work the same as all these other APIs and in particular it's
now largely cross-compatible with ORM query as well.
The reason select() has always accepted a a list is because the very ancient
and long de-emphasized API for select() looked like this:
stmt= select({table.c.col1, table.c.ol2], table.c.col1 == "some_expression",
order_by=table.c.col1)
that is, the "generative" API for select() that is very normal now did not
exist. There was no select().where().order_by(), that was all added years
after SQLAlchemy's first releases. All of those kwargs are also deprecated
as they are very ancient legacy code and we'd like SQLAlchemy's API to be clean
and consistent and not allowing of many variations of the same thing, as this
makes the whole system easier to use and understand.
So the use of a list in select() is based on long ago deemphasized API that
SQLAlchemy 2.0 seeks to finally remove. As this API is one of the most
complicated to provide a backwards-compatibility path for, it's taken a very
long time for us to get there. But here we are.
On Thu, May 13, 2021, at 2:10 AM, mkmo...@gmail.com
<mailto:mkmo...%40gmail.com> wrote:
> Hello,
>
> I am on Sqlalchemy 1.2 and looking to upgrade to 1.4.
>
> I have a lot of Core code that looks like this:
>
> # returns an array of columns
> select_fields = make_select_fields(...)
> sel = select(select_fields)
>
> Passing an array to select is now deprecated, so I'm planning on changing all
> my code to:
>
> sel = select(*select_fields)
>
> I was curious to know what the rationale for the change in this API is.
>
> Thanks and best regards,
>
> Matthew
>
>
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SQLAlchemy -
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http://www.sqlalchemy.org/
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