Question about Banner Alerts applying to all active patients

[rmagier1]

In the documentation there is a sentence

To apply the effect to all active patients when a plugin is created or updated, include the PLUGIN_CREATED and/or PLUGIN_UPDATED events in the RESPONDS_TO list. Additionally, patient_filter can be used (instead of patient_id) on the AddBannerAlert class.

We are building a plugin that will calculate and display starting BMI and weight loss percentages in this PR. It works great when it is triggered on the Interview or Observation Create/Update events in real time. However, I want to make sure that on the protocol being installed or updated, since it contains calculations, that the code is then triggered to recompute for all active patients. Sounds like using the patient_filter would be useful. However, I need the narrative string in the banner to calculated for each patient. Since the narrative can't be a function, I am unable to use the patient_filter in the AddBannerAlert class. The only alternative solution I see would be to loop through patients in the Data Module manually, but I worry that is bad performance depending on how many patients and records are to be queried. What is the best approach?

[aduane]

@mbiannaccone do you have any suggestions here?

[mbiannaccone]

custom patient-specific values when applying an effect to multiple patients using a patient_filter is not supported right now, but i do agree that it should be supported. i can't think of any workarounds at the moment (definitely don't think looping through each patient manually is a good idea), but we should brainstorm on the best way to enable this behavior. i kind of like the idea of being able to pass in a function, or even some kind of string templating (i.e. narrative="{Patient.first_name} is sick"), but it warrants a deeper discussion to figure out the best path forward. @rmagier1 as the developer here, what's your opinion on the easiest/most ergonomic way to pass in a custom text per patient?

[rmagier1]

I like the ability to pass in a function. Especially with this use case where we need to perform a calculation. But how do you envision it working when you need access to data in the Data Module for that specific patient. I see a simple case of something like this

banner = AddBannerAlert(
    key="test-alert",
    patient_filter = {"active": True},
    narrative=narrative_func
    placement=[AddBannerAlert.Placement.CHART],
    intent=AddBannerAlert.Intent.INFO,
)


# have a function that takes a patient as the parameter 
# so you can call this function with the patients that 
# come back from the patient_filter
def narrative_func(patient):

    # find current weight of patient to display 

    current_weight = Observation.objects.filter(
        patient=patient,
        deleted=False, 
        entered_in_error_id__isnull=True,
        committer_id__isnull=False,
        category='vital-signs',
        name='weight'
    ).exclude(value='').order_by('created').last()

    # need to know to not add the banner though?
    # if None is returned for the narrative,
    if not current_weight:
        return None

    return f"{patient.first_name} has a current weight of {current_weight.value}"

But questions are:

1. When this function runs will it have access to the Data Module or things imported
2. If the calculation reveals that this banner shouldn't be shown for this patient in the backfill, can a return of None skip adding?