On Feb 4, 2013, at 1:04 AM, ru...@yahoo.com wrote:
> simply didn't get from the docs. Like the fact that I could
> create a mapped object simply with
>
> class User: pass
>
> rather than explicitly specifying all the attributes. Without
> that I wouldn't even be trying to use sqlalchemy today.
Well, the majority of users who see "class User" and then the separate
"mapper()" + "Table" step, which for many years was how we documented it, would
lead new users to say, "what! that's so verbose! I'm going back to Django
where I can define everything inline". So a lot more people weren't trying to
use us on that side of things :) Also, I personally found class + mapper() +
Table to be unworkable in practice - declarative offers all kinds of advantages
over the plain approach and greatly reduces boilerplate and redundancy. Often
I will keep the Table metadata explicit but just define it within the
declarative class as such:
class SomeClass(Base):
__table__ = Table('sometable', Base.metadata,
Column(...),
...
)
that style is documented at
http://docs.sqlalchemy.org/en/rel_0_8/orm/extensions/declarative.html#using-a-hybrid-approach-with-table
.
The ORM tutorial is really quite carefully written, to make sure people are at
least somewhat aware, as they are seeing SQLAlchemy ORM usage for the first
time, that they are building upon a system that can be broken into smaller
parts:
With our User class constructed via the Declarative system, we have defined
information about our table, known as table metadata, as well as a user-defined
class which is linked to this table, known as a mapped class. Declarative has
provided for us a shorthand system for what in SQLAlchemy is called a
“Classical Mapping”, which specifies these two units separately and is
discussed in Classical Mappings. The table is actually represented by a
datastructure known as Table, and the mapping represented by a Mapper object
generated by a function called mapper(). Declarative performs both of these
steps for us, making available the Table it has created via the __table__
attribute:
"Classical mappings" is linked, you go there, and see the traditional mapping,
a plain User class with nothing but a constructor. The constructor is not
needed and at the moment this appears to not be mentioned.
>> > logging is fully described here:
>> >
>> > http://docs.sqlalchemy.org/en/rel_0_8/core/engines.html#configuring-logging
> Thanks. Since logging applies to other parts of Sqlalchemy besides
> the engine, would it be better if this were in it own section? Even
> if not, I think it would help if logging had a link in the table of
> contents page (http://docs.sqlalchemy.org/en/rel_0_8/)
logging is really about the "Engine" and the "Pool", which is closely tied to
the Engine. Logging for other areas is being de-emphasized as it isn't
generally used.
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