On Tuesday, December 6, 2016 at 3:41:38 PM UTC-8, Richard wrote: > > UP, never get any answer... >
How would this differ from reference fields? /dps > > On Sat, Jan 23, 2016 at 4:08 PM, Val K <[email protected] <javascript:>> > wrote: > >> Hi guys! >> I have an idea to improve DAL in scope of work with normalized DB. >> As known It's a common practice to avoid NULL value by creating separate >> (option) table(s) to store non required fields. >> So, it would be great to have a field type like "storedin >> table_name.field_name" >> For example: >> >> db.define_table('alias_opt', Field('name'), Field('alias_name', 'reference >> person')) >> db.define_table('person', Field('name'), Field('alias_name', 'storedin >> alias_opt.alias_name')) >> >> #INSERT: >> db.person.insert(name='Alex', alias_name='Macedonian') >> # means: >> id=db.person.insert(name='Alex') >> db.alias_opt.insert(id=id, alias_name='Macedonian') >> >> #UPDATE: >> db(db.person.id==id).update(... , alias_name=None) >> # means: >> # update person >> ... >> # update option table >> update_opt_args = filter_storedin_fields(update_args) >> opt_rec = db.alias_opt(id) >> opt_rec.update(update_opt_args) >> if not any(opt_rec.values()): # - all fields of option table record >> is None >> del db.alias_opt(id) >> else: >> db.alias_opt.update_or_insert(id==id, **update_opt_args) >> >> #DELETE: >> del db.person(id) also means del db.alias_opt(id), like ondelete= >> 'CASCADE' >> >> #SELECT: >> rows = db(db.person).select() >> # means: >> rows = db(db.person).select( left=[ db.alias_opt.on( db.alias_opt.id == >> db.person.id ) ] ) >> but only "storedin" fields should be selected from db.alis_opt >> and they should be accessed by row.alias_name (not only by row. >> joined_table.field_name ) >> >> Considering, that table person could be a VIEW (i.e. JOIN is already >> performed at DB level), there is no need to make join at web2py level, >> it could be fixed by passing an option arg like is_view=True to >> define_table() >> I know, that behavior of insert/update/delete could be easy realized by >> custom class based on Table >> with a little hacking Field-class to intercept field type to fix it to >> web2py type ( considering person.alias_name.type == >> alias_opt.alias_name.type ). >> But it's hard for me to change select() behavior, because there is only >> common_filter, but there isn't common_join/common_left with providing of >> maping (aliasing) joined table fields to 'storedin' fields. >> >> In fact, I dream of common_join depends on discriminator field, that will >> switch tables to be joined depend on discriminator value specified in the >> query (something like db.object.type_id==type_id), >> if descriminator is not specified or couldn't be resolved at web2py >> level, it performs left join all tables (from a list containing possible >> common_join tables) >> >> P.S. May be I try to reinvent the wheel, so feel free to shoot me! >> >> -- >> 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) >> --- >> You received this message because you are subscribed to the Google Groups >> "web2py-users" group. >> To unsubscribe from this group and stop receiving emails from it, send an >> email to [email protected] <javascript:>. >> For more options, visit https://groups.google.com/d/optout. >> > > -- 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) --- You received this message because you are subscribed to the Google Groups "web2py-users" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. For more options, visit https://groups.google.com/d/optout.
