models.py with django_dag models for parts hierarchy
This is a portion of my code for creating a hierarchical relation between assemblies, subparts, and parts and so forth (although really, everything is a Part) The project being used is [django_dag](https://github.com/elpaso/django-dag) For the sake of example, let's use this structure: * Bike 1 * - Front Tire & Back Tire combo 000 * - - Front Tire 000 * - - Rear Tire 000 * - Frame 000 * - Gearset type 000 * - - Crank 000 * - - Rear Cassette 000 * . * Bike 2 * - Front Tire & Back Tire combo 001 * - - Front Tire 001 * - - Rear Tire 000 * - Frame 001 * - Gearset type 000 * - - Crank 000 * - - Rear Cassette 000 Using the above example, I couldn't use a MPTT structure because Gearset 000 is used in 2 different parents (bike 1 and bike 2). So I had to use the DAG [(wiki)](http://en.wikipedia.org/wiki/Directed_acyclic_graph) structure which allows multiple parents. The `Relationship` model holds the dag information, mainly a parent and child field. (Tire combo 001 is child of Bike2, front tire 001 is child of tire combo 001, etc) After get the dag structure using the `ancestors_tree` method on a Part object, I search for the BillOfMaterial info for that whole tree. In my case the Bill Of Material info is unique per assembly, so that's why there are seperate models. It becomes a bit of a pain to have to save/delete both the relationship and BoM models at the same time, and to check if one exists to create the other etc. But I've made my first 'hack' through it to have a function project, and am ready to make some revisions now.
- models
- hierarchy
- dhango_dag
- django-dag