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Base classes for visit reports/tracking in clinicedc/edc

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Track study participant visit reports.

Declaring a visit model

A visit_model is declared using the model mixin VisitModelMixin. Normally, a visit_model will be declared with additional model mixins, but VisitModelMixin must be there.

class SubjectVisit(VisitModelMixin, BaseUuidModel):

Also, ensure the Meta class attributes of VisitModelMixin are inherited. These include required constraints and ordering.

class SubjectVisit(VisitModelMixin, BaseUuidModel):


    class Meta(VisitModelMixin.Meta):

Among other features, VisitModelMixin adds a OneToOneField foreign key to the visit_model that points to edc_appointment.Appointment.

Important: A visit model is a special model in the EDC. A model declared with the model mixin, VisitModelMixin, is the definition of a visit model. CRFs and Requisitions have a foreign key pointing to a visit model. A number of methods on CRFs and Requisitions detect their visit model foreign key name, model class and value by looking for the FK declared with VisitModelMixin.

For a subject that requires ICF the visit model would use the RequiresConsentModelMixin:

class SubjectVisit(

    class Meta(VisitModelMixin.Meta, BaseUuidModel.Meta):

If the subject does not require ICF, such as an infant, don’t include the RequiresConsentModelMixin:

class InfantVisit(

    class Meta(VisitModelMixin.Meta, , BaseUuidModel.Meta):

A more complete declaration will include model mixins from other libraries. For example:

from edc_consent.model_mixins import RequiresConsentFieldsModelMixin
from edc_metadata.model_mixins.creates import CreatesMetadataModelMixin
from edc_model.models import BaseUuidModel
from edc_offstudy.model_mixins import OffstudyVisitModelMixin
from edc_sites.models import CurrentSiteManager
from edc_sites.models import SiteModelMixin
from edc_visit_tracking.managers import VisitModelManager
from edc_visit_tracking.model_mixins import VisitModelMixin

class SubjectVisit(

    objects = VisitModelManager()

    on_site = CurrentSiteManager()

    history = edc_models.HistoricalRecords()

class Meta(VisitModelMixin.Meta, BaseUuidModel.Meta):

Declaring a CRF

The CrfModelMixin is required for all CRF models. CRF models have a OneToOneField key to a visit model.

class CrfOne(CrfModelMixin, OffstudyCrfModelMixin, RequiresConsentModelMixin,
             UpdatesCrfMetadataModelMixin, BaseUuidModel):

    subject_visit = models.OneToOneField(SubjectVisit)

    f1 = models.CharField(max_length=10, default='erik')

    vl = models.CharField(max_length=10, default=NO)

    rdb = models.CharField(max_length=10, default=NO)

    class Meta:
        consent_model = 'myapp.subjectconsent'  # for RequiresConsentModelMixin

Declaring forms:

The VisitFormMixin includes a number of common validations in the clean method:

class SubjectVisitForm(VisitFormMixin, FormValidatorMixin, forms.ModelForm):

    form_validator_cls = VisitFormValidator

    class Meta:
        model = SubjectVisit


The PreviousVisitModelMixin ensures that visits are entered in sequence. It is included with the VisitModelMixin.



Missed Visit Report

A detail report should be submitted for scheduled visits that are missed. By selecting the reason missed visit on SubjectVisit, only the missed visit CRF will be required for the timepoint. All other CRFs and requisitions will be excluded.

Unscheduled visits cannot be missed. (To change this behaviour see settings attrubute EDC_VISIT_TRACKING_ALLOW_MISSED_UNSCHEDULED)

The model mixin SubjectVisitMissedModelMixin provides the basic features of a SubjectVisitMissed model.

In your subject app declare:

from django.db.models import PROTECT
from edc_crf.model_mixins import CrfWithActionModelMixin
from edc_model import models as edc_models
from edc_visit_tracking.model_mixins import SubjectVisitMissedModelMixin

class SubjectVisitMissed(SubjectVisitMissedModelMixin, edc_models.BaseUuidModel):

    missed_reasons = models.ManyToManyField(
        SubjectVisitMissedReasons, blank=True, related_name="+"

    class Meta(CrfWithActionModelMixin.Meta, edc_models.BaseUuidModel.Meta):
        verbose_name = "Missed Visit Report"
        verbose_name_plural = "Missed Visit Report"

In your list model app, e.g. meta_lists, declare the list model:

class SubjectVisitMissedReasons(ListModelMixin):
    class Meta(ListModelMixin.Meta):
        verbose_name = "Subject Missed Visit Reasons"
        verbose_name_plural = "Subject Missed Visit Reasons"

… and update the list_data dictionary, for example:

list_data = {
"meta_lists.subjectvisitmissedreasons": [
    ("forgot", "Forgot / Can’t remember being told about appointment"),
    ("family_emergency", "Family emergency (e.g. funeral) and was away"),
    ("travelling", "Away travelling/visiting"),
    ("working_schooling", "Away working/schooling"),
    ("too_sick", "Too sick or weak to come to the centre"),
    ("lack_of_transport", "Transportation difficulty"),
    (OTHER, "Other reason (specify below)",),

Window period

By default, the visit report_datetime is validated to stay within the same window period as the appointment. This may be too restrictive in some cases.

To bypass this override `validate_visit_datetime_in_window_period` in the `VisitFormValidator`

from edc_visit_tracking.form_validators import VisitFormValidator as BaseVisitFormValidator

class VisitFormValidator(BaseVisitFormValidator):


    def validate_visit_datetime_in_window_period():


Be sure that your appointment form validator is enforcing window periods before bypassing this check.

See also edc_appointment.

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