Hi all,
I'd like to investigate a possible "special" usage/abuse of comments on schema
objects, available for example under PostgreSQL.
In many applications, I use the "info" slot of table's columns to store visual
settings, mainly a "label" and an "hint", something like
class Player(GloballyUnique, Base):
"""A single person."""
__tablename__ = 'players'
"Related table."
## Columns
idplayer = Column(
intid_t, Sequence('gen_idplayer', optional=True),
primary_key=True,
nullable=False,
info=dict(label=N_('Player ID'),
hint=N_('Unique ID of the player.')))
"""Primary key."""
firstname = Column(
name_t,
nullable=False,
info=dict(label=N_('First name'),
hint=N_('First name of the player.')))
"""Player's first name."""
Those strings are then picked up (and possibly translated) by a library[*]
that exposes a SA selectable as a webservice, producing either a "meta
description" of its resultset (that a client app can use to configure a
grid/table/form to display/edit it), or effectively executing the query given
required parameters.
This morning I was asked "would it be possible to use PG `col_description()`
for that, storing the info slot as a JSON string in the database itself,
opening the way of using SA reflection capability instead of an explicit
declaration?". Uhm, what he said!
I spent some time inside SA code, to understand if/where I could hook an
extension to the reflection mechanism that would allow me to fetch such extra
information for each column. It seems that the `Inspector.get_columns()`
declares an "attrs" slot, carrying "optional column attributes", but no
dialect uses it AFAICT.
I could of course tweak/monkey patch the `PGDialect.get_columns()`, but I
wonder if there is a better way hidden somewhere (... it wouldn't be a great
surprise! :-).
What would you suggest?
Thanks for any hint,
ciao, lele.
[*] https://pypi.python.org/pypi/metapensiero.sqlalchemy.proxy
--
nickname: Lele Gaifax | Quando vivrò di quello che ho pensato ieri
real: Emanuele Gaifas | comincerò ad aver paura di chi mi copia.
[email protected] | -- Fortunato Depero, 1929.
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