On Apr 12, 9:14 pm, Anthony <alantho...@gmail.com> wrote: > I'm struggling on whether or not to implement GroupItem (below) with > two separate models, or with one model that has a distinguishing key: > > Given: > class ParentGroup: > a group of values represented by class GroupItem > > class ChildGroup: > a group of values represented by class GroupItem > foreign-key to ParentGroup (many Children sum to one Parent) > > Option A: > class GroupItem: > foreign-key to ParentGroup > foreign-key to ChildGroup > GroupItemType in (ParentItem, ChildItem) > value > value-type > > Option B: > class ParentGroupItem > foreign-key to ParentGroup > value > value-type > > class ChildGroupItem > foreign-key to ChildGroup > value > value-type > > What are my considerations when making this decision? > > Thanks!
You want a ChildItem to have membership in two collections: ParentGroup and ChildGroup. You also want a ParentItem to have membership in one collection. For example: parentA: itemPA1, itemPA2, childA, childB childA: itemCA1, itemCA2 childB: itemCB1, itemCB2 Or, listing by child, itemPA1: parentA itemPA2: parentA itemCA1: childA itemCA2: childA itemCB1: childB itemCB2: childB childA: parentA childB: parentA Correct so far? -- http://mail.python.org/mailman/listinfo/python-list
