>
> >>> table.name='entry'
>
I assume that should be "table_name".
> >>> table=eval('db.'+table_name)
>
No need to use eval -- just do db[table_name].
>
> >>> field_names=table.fields
> >>> print field_names
> ['id', 'txn_id', 'acc_id', 'debit', 'credit']
>
No need to store field names -- just use table.fields directly.
>
> >>> fields=[table[field] for field in field_names]
>
No need to generate a separate list of the Field objects if all you need it
for is to iterate over it later -- instead, you can just iterate over the
Table object, which will yield its Field objects. For example:
[f.type for f in table]
>
> >>> refs=['db.'+table_name+'.'+field.name+' == db.'+field.type[10:]+'.id'
> for field in fields if field.type[:9]=='reference']
> >>> print refs
> ['db.entry.txn_id == db.txn.id', 'db.entry.acc_id == db.acc.id']
>
> >>> q=eval('('+') & ('.join(refs)+')')
> >>> print q
> ((entry.txn_id = txn.id) AND (entry.acc_id = acc.id))
>
No need to build the code as strings and then eval. Instead, you can do:
[db[table_name][field.name] == db[field.type[10:]].id for field in fields
if field.type[:9] == 'reference']
Actually, the whole thing can be done a little more easily by accessing the
._references and .referent attributes:
table_name = 'entry'
query = reduce(lambda a, b: a & b,
(f == f.referent for f in db[table_name]._references))
rows = db(query).select()
Note, if the table might contain any list:reference fields, those will need
to be filtered out:
table_name = 'entry'
query = reduce(lambda a, b: a & b,
(f == f.referent for f in db[table_name]._references
if not f.type.startswith('list:')))
rows = db(query).select()
Anthony
--
Resources:
- http://web2py.com
- http://web2py.com/book (Documentation)
- http://github.com/web2py/web2py (Source code)
- https://code.google.com/p/web2py/issues/list (Report Issues)
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