django integration + support

[rlskoeser]

requirements

• django is an optional dependency
• database storage of dates - ideally single field (somehow)
  • query, filter, sort
    • querying and filtering should be fast - consider benchmarks we want to meet
  • target postgres only to start (take advantage of daterange, json fields)
    • future enhancement: support sqlite
  • ideally support: EDTF date range, label, alternate calendars, conversion, mixed precision, (uncertainty ? )
• django admin integration
  • widget / form field (defaults)
  • optional parsing / conversion from label field to structured field
• import / export support (django-import-export - provide standard resources for undate dates)
• serialization for django dumpdata command (import/export)

assumptions

• no REST API implementation in first pass

nice to have

• custom queryset filters that are undate aware (one example in shakespeare & company codebase for known year)
• admin date drill-down equivalent
• django custom template tag for formatting dates (?) (one version in S&co codebase, but better as core undate functionality )
• convert for Solr indexing
• easy migration path from custom solutions (CDH geniza, s&co; python-edtf ? )

sub issues

• setup package with django optional dependency & test matrix with/without django
  • TBD versions of django?