What is the proper way to get pluralized shortened names for many-to-many
tables when using automap? I currently have it set to generate pluralized
lowercase names for collections instead of the default "_collection". This
is what I want for one-to-many or many-to-one relationships, but not
many-to-many. For example, I have two tables, hdu, and extcol, joined
together through a many-to-many table, hdu_to_extcol
create table hdu (pk serial primary key not null, extname_pk integer,
exttype_pk integer, extno integer, file_pk integer);
create table hdu_to_extcol (pk serial primary key not null, hdu_pk integer,
extcol_pk integer);
create table extcol (pk serial primary key not null, name text);
ALTER TABLE ONLY mangadapdb.hdu_to_extcol
ADD CONSTRAINT hdu_fk
FOREIGN KEY (hdu_pk) REFERENCES mangadapdb.hdu(pk)
ON UPDATE CASCADE ON DELETE CASCADE;
ALTER TABLE ONLY mangadapdb.hdu_to_extcol
ADD CONSTRAINT extcol_fk
FOREIGN KEY (extcol_pk) REFERENCES mangadapdb.extcol(pk)
ON UPDATE CASCADE ON DELETE CASCADE;
When I use SQLalchemy to automap the Base classes, the relationship this
generates on the Hdu and Extcol classes are *Hdu.hdu_to_extcol, and
Extcol.hdu_to_extcols*, using the below pluralize, and relationship, code.
However, ideally what I'd like the names to be are *Hdu.extcols, and
Extcol.hdus*, respectively. What's the best to generate this for these
many-to-many tables? I'm not sure if automap is recognizing these as
many-to-many tables. The direction indicated when I print during the
relationship stage don't indicate as such.
symbol('ONETOMANY') <class 'sqlalchemy.ext.automap.Extcol'> extcol
symbol('MANYTOONE') <class 'sqlalchemy.ext.automap.HduToExtcol'>
hdu_to_extcol
symbol('ONETOMANY') <class 'sqlalchemy.ext.automap.Hdu'> hdu
symbol('MANYTOONE') <class 'sqlalchemy.ext.automap.HduToExtcol'>
hdu_to_extcol
Here is my Base class generation code.
def _gen_relationship(base, direction, return_fn, attrname, local_cls,
referred_cls, **kw):
if local_cls.__table__.name in onetoones:
kw['uselist'] = False
# make use of the built-in function to actually return the result.
return generate_relationship(base, direction, return_fn, attrname,
local_cls, referred_cls, **kw)
_pluralizer = inflect.engine()
def pluralize_collection(base, local_cls, referred_cls, constraint):
referred_name = referred_cls.__name__
uncamelized = re.sub(r'[A-Z]', lambda m: "_%s" % m.group(0).lower(),
referred_name)[1:]
pluralized = _pluralizer.plural(uncamelized)
return pluralized
# Grabs engine
db = DatabaseConnection()
engine = db.engine
# Selects schema and automaps it.
metadata = MetaData(schema='mangadapdb')
Base = automap_base(bind=engine, metadata=metadata)
Base.prepare(engine, reflect=True, classname_for_table=camelizeClassName,
name_for_collection_relationship=pluralize_collection, generate_relationship
=_gen_relationship)
# Explicitly declare classes
for cl in Base.classes.keys():
exec('{0} = Base.classes.{0}'.format(cl))
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