On Thu, Feb 8, 2018 at 3:29 PM, Jeremy Flowers
<jeremy.g.flow...@gmail.com> wrote:
> I've seen you can do things like this:
> fields = ['jobmst_type', 'jobmst_name']
> print(session.query(Jobmst).options(load_only(*fields)).first())
>
> But according to the documentation, you should be able to do something with
> Query values() too.
> But once again I seem to be dumbfounded by the syntatic sugar.
>
> What data type does the list of values need?
> Is there a way to introspect that ahead of time?
.values() is a weird method and it's pretty old, usually people just
set the columns up front:
session.query(Jobmst.jobmst_name, Jobmst.jobmst_type)
to use values, looks similar:
session.query(Jobmsg).values(Jobmst.jobmst_name, Jobmst.jobmst_type)
all those docstrings could use examples, not just for Query but
throughout the whole Core too.
with_entities() does this too:
query(Jobmst).with_entities(Jobmst.jobmst_name, Jobmst.jobmst_type).all()
docs for that are above and the formatting is screwed up, let me fix that
>
> Thought I was onto something with .base_columns, but that didn't work
> either...
>
> I ended up with something like an instrumentalAttributes mismatch.
> print(session.query(Jobmst)
> .values([Jobmst.jobmst_type.base_columns,
> Jobmst.jobmst_name.base_columns
> ])
> .first()
in Python, when you see method(*params) with the asterisk, you send
each element individually:
method('a', 'b', 'c', 'd', ...)
without the asterisk, you'd send the list.
> )
>
> sqlalchemy.exc.InvalidRequestError: SQL expression, column, or mapped entity
> expected - got '[{Column('jobmst_type', Numeric(scale=0, asdecimal=False),
> table=<jobmst>, nullable=False)}, {Column('jobmst_name', String(length=256),
> table=<jobmst>, nullable=False)}]'
>
> BTW: I'm aware of querying with things like query(Jobmst.jobmst_type,
> Jobmst.jobmst_name) too - but looking to understand what values expects.
> Mike, Can documentation not specify type?
>
> --
> SQLAlchemy -
> The Python SQL Toolkit and Object Relational Mapper
>
> http://www.sqlalchemy.org/
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SQLAlchemy -
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