edc-reference

Pivoted reference table for EDC modules

edc_reference creates a pivoted table of CRF and Requisition records with a small subset of values that can be efficiently referenced. The module is used by edc_metadata_rules to quickly determine if a CRF or Requisition model instance exists avoiding the need to query each individual model class.

See also edc_metadata_rules

Usage and Configuration

Declare a model with the ReferenceModelMixin.

from edc_reference.model_mixins import ReferenceModelMixin

class CrfOne(ReferenceModelMixin, BaseUuidModel):

    subject_visit = models.ForeignKey(SubjectVisit, on_delete=PROTECT)

    report_datetime = models.DateTimeField(default=get_utcnow)

    f1 = models.CharField(max_length=50)

    f2 = models.CharField(max_length=50)

    f3 = models.CharField(max_length=50)

    f4 = models.DatetimeField(null=True)

Register the model and the relevant fields with the site global, site_reference_configs:

from edc_reference.site_reference import ReferenceModelConfig

reference = ReferenceModelConfig(
    model='edc_reference.crfone',
    fields=['f1', 'f4'])
site_reference_configs.register(reference)

Create a model instance:

crf_one = CrfOne.objects.create(
    subject_visit=subject_visit,
    f1='happiness'
    f4=get_utcnow())

The Reference model will be updated:

from edc_reference.models import Reference

reference = Reference.objects.get(
    identifier=self.subject_identifier,
    timepoint=self.subject_visit.visit_code,
    report_datetime=crf_one.report_datetime,
    field_name='f1')

>>> reference.__dict__
{ ...
 'datatype': 'CharField',
 'field_name': 'f1',
 'identifier': '1',
 'model': 'edc_reference.crfone',
 'report_datetime': datetime.datetime(2017, 7, 7, 13, 30, 6, 545140, tzinfo=<UTC>),
 'timepoint': 'code',
 'value_date': None,
 'value_datetime': None,
 'value_int': None,
 'value_str': 'happiness',
 ...}

Get the value from the reference instance:

>>> reference.value
'happiness'

Model managers methods are also available, for example:

reference = Reference.objects.crf_get_for_visit(
    model='edc_reference.crfone',
    visit=self.subject_visit,
    field_name='f1')

>>> reference.value
'happiness'

Accessing pivoted data with LongitudinalRefset

TODO