Yannick Gingras wrote:
>
> Hi, I use Alchemy to connect to a legacy system with horrible table
> and column names. Here is a snippet to give you an idea:
>
> po_details_table = Table('F4311', meta.metadata,
> Column("PDKCOO", String, primary_key=True),
> Column("PDDOCO", Integer, primary_key=True),
> Column("PDDCTO", String,
> ForeignKey(order_rules_table.c.FSDCTO),
> primary_key=True),
> Column("PDSFXO", String, primary_key=True),
> Column("PDLNID", Integer, primary_key=True),
>
> # Dates
> Column("PDDRQJ", JDEDate),
> Column("PDTRDJ", JDEDate),
>
> # Desc
> Column("PDDSC1", Unicode),
> Column("PDDSC2", Unicode),
>
> # Status
> Column("PDNXTR", String,
> ForeignKey(order_rules_table.c.FSTRTY)),
> Column("PDLTTR", String,
> ForeignKey(order_rules_table.c.FSTRTY)),
> Column("PDLNTY", String,
> ForeignKey(order_rules_table.c.FSLNTY)),
>
> schema="PRODDTA")
>
> As you can imagine, I quickly added a few synonyms to my objects:
>
> def add_synonyms(props, synonyms):
> """ expand a {k:v} mapping to a list of synonym properties """
> props.update(dict([(k, synonym(v)) for k, v in synonyms.items()]))
> return props
>
> mapper(PODetail, po_details_table,
> properties=add_synonyms(
> dict(status_rule_next=relation(OrderRule, primaryjoin=_next_join),
> status_rule_last=relation(OrderRule, primaryjoin=_last_join)),
> dict(company="PDCO",
> company_order_key="PDCOO",
> business_unit="PDMCU",
>
> order_type="PDDCTO",
> line_type="PDLNTY",
>
> document_id="PDDOCO",
> line_no="PDLNID",
>
> date_requested="PDDRQJ",
> date_transaction="PDTRDJ")
> )
> )
>
> So far so good but I still need to do the joins with the column names
> in po_details_table and those don't have human friendly synonyms. Is
> there a way to create my synonyms mapping in the table object instead
> in doing it in the object mapper?
Yes, columns can be renamed with the key= argument:
Column("PDDRQJ", JDEDate, key='date_requested')
The key name replaces the true database column name everywhere in Python
code, so you won't need the mapper options any longer. Note that
everywhere includes specifying foreign key references:
Column("PDDCTO", String,
ForeignKey(order_rules_table.c.order_type),
primary_key=True)
and when specifying FKs as strings:
Column("PDDCTO", String,
ForeignKey('F3434whatever.order_type'),
primary_key=True)
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