Hello,
I'm new to sqlalchemy and wondered how could I do this :
I have 2 tables (postgresql) :
create table invasive_categories (
id serial not null,
category varchar(100) not null,
constraint pk_category
primary key(id)
);
create table invasives (
id serial not null,
original_name varchar(200) not null,
added timestamp not null default
current_timestamp,
category integer not null,
constraint pk_invasive
primary key (id),
constraint fk_category
foreign key (category) references invasive_categories(id)
);
I've done this :
from sqlalchemy import *
class Invasive(object): pass
class InvasiveCategory(object): pass
db_engine =
create_engine('postgres://database=blabla&host=blabla.com&user=foo&password=bar',
encoding='utf-8')
invasives = Table('invasives', db_engine, autoload = True)
invasive_categories = Table('invasive_categories', db_engine,
autoload=True)
Invasive.mapper = mapper(Invasive, invasives)
InvasiveCategory.mapper = mapper(InvasiveCategory, invasive_categories)
cascade_mappers(Invasive.mapper, InvasiveCategory.mapper) // Invasive
contains invasivecategory and InvasiveCategory contains invasives
It works, but how could I select all "Invasive" order by
InvasiveCategory.category ?
I tried things like:
Invasive.mapper.select_by(order_by=[invasivecategory.category])
Invasive.mapper.select(order_by=[InvasiveCategory.c.category]) // This
query doesn't fail, but a JOIN is missing ... (why ?)
...
Another question, why can't I select only some fields in a select_text()
? For example :
Invasive.mapper.select_text('SELECT a.* FROM invasives a,
invasive_categories b WHERE a.category=b.id') works
but Invasive.mapper.select_text('SELECT a.original_name FROM invasives
a, invasive_categories b WHERE a.category=b.id') fails ...
In advance, thanks for you answers
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