I chose approach B and it works fine. Thanks for mentioning drop downs. Kind regards,
Jan Am Donnerstag, 11. September 2014 17:24:40 UTC+2 schrieb Richard: > > B will help you filter your drop down of component package if you can only > have in a package the same supertype component. > > Difficults to say without concrete example. > > Richard > > On Thu, Sep 11, 2014 at 9:58 AM, Jan Beilicke <jan.be...@gmail.com > <javascript:>> wrote: > >> These are just sample names. In reality they are separate business/use >> case entities sharing only the same supertype, they are not enumerated. >> >> Am Donnerstag, 11. September 2014 15:42:47 UTC+2 schrieb Richard: >>> >>> Why component_a, _b, _c... You will end up create new table all the >>> time... >>> >>> Richard >>> >>> On Thu, Sep 11, 2014 at 7:04 AM, Jan Beilicke <jan.be...@gmail.com> >>> wrote: >>> >>>> Hi everyone, >>>> >>>> I'm working on a web2py project which requires a complex relationship >>>> model. I want to use a model that works well with web2py's DAL and I would >>>> be glad if somebody could point me into the right direction. >>>> >>>> I created a small sample ER diagram to illustrate my problem, only the >>>> important parts are displayed and the table names are generalized for >>>> easier understanding. The database has a couple of tables (or business >>>> objects), most of them are depending on some supertype, let's call it >>>> 'component_type', the subtypes 'component_[a-z]'. >>>> >>>> The business case requires to create a component_package which contains >>>> required components, but *all components in the package must be of the >>>> same component_type.* >>>> >>>> Two possible variants are shown in the illustration: >>>> >>>> Variant A: The component_package contains the foreign keys of the >>>> component tables. >>>> Variant B: The package additionally contains the foreign key of the >>>> component_type table. >>>> >>>> Which variant would you recommend and which one might work better with >>>> DAL? Unfortunately, all the resources and database design documents I >>>> found >>>> in the web were only explaining the general supertype/subtype relation. >>>> >>>> Thank you in advance and >>>> kind regards, >>>> >>>> Jan >>>> >>>> >>>> <https://lh3.googleusercontent.com/-zgZdMMjkmwg/VBF_6_5O2FI/AAAAAAAAAYc/PXyEaTB32iQ/s1600/relation_problem.png> >>>> >>>> -- >>>> 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 web2py+un...@googlegroups.com. >>>> 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 web2py+un...@googlegroups.com <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 web2py+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
