Blueprint for Many-to-Many

Update: This is somewhat resolved, through a manual method. See budget's kit_item() or bundle_kit_item() for examples.

• ​http://www.tomjewett.com/dbdesign/dbdesign.php?page=manymany.php

We need Many-to-Many support for GIS Feature Groups (to be able to select a mixture of Feature Classes &/or individual Features) & for the Person Registry & Organisation Registry

Web2Py doesn't really support Many-to-Many SQL tables.

• even though the t2_membership table is one

It can kind-of do it using Tagging widgets:

• t2.tag_widget()
• ​multiple=True

These are great for selecting between a relatively small number of options (the second supports the ​jquery multiselect plugin).
However they aren't scalable (too many elements in large lists).

• Mitigate using Auto-complete?

They also don't have proper referential integrity.

I think the ideal should be something like:

• ​http://code.google.com/p/django-ajax-filtered-fields/

If we can make something generic enough then Massimo will be keen to incorporate it.

jQuery MultiSelect plugin: ​http://plugins.jquery.com/project/Multiselect

My request to Web2Py list:

• ​http://groups.google.com/group/web2py/browse_thread/thread/414fd05976f97226/

Other pertinent posts:

• ​http://groups.google.com/group/web2py/browse_thread/thread/89b117d74c611747
• Multiple Lookup table: ​http://groups.google.com/group/web2py/msg/b69898ec49dcef71

---

BluePrints