Feature add simple family cache management

[mngoe]

Add simple Family cache management as a start for GraphQL cache test.

Not so much performance impact at this stage, but I can imagine that each database request removed is an improvement.

We will still have few changes to implement :

• Delete Cache value on FHIR family mutation
• Manage cache version to manage field requests (if family detail requested field change from one request to another this implementation will not work).

[delcroip]

here perplexity answer regarding additionnal sub fields:

Yes, you can cache a Django object along with its first level of related resources. Here's how you can implement this:

Caching Strategy

To cache a Django object with its first level of related resources, you can use Django's low-level cache API. This approach allows you to cache the main object and its related objects together.

Implementation

1. Create a custom caching function:

from django.core.cache import cache
from django.db import models

def cache_object_with_relations(obj, timeout=3600):
    key = f"{obj._meta.model_name}:{obj.pk}"
    cached_data = {
        'main': obj,
        'relations': {}
    }

    for field in obj._meta.get_fields():
        if isinstance(field, models.ForeignKey) or isinstance(field, models.OneToOneField):
            related_obj = getattr(obj, field.name)
            if related_obj:
                cached_data['relations'][field.name] = related_obj
        elif isinstance(field, models.ManyToManyField):
            related_objs = getattr(obj, field.name).all()
            cached_data['relations'][field.name] = list(related_objs)

    cache.set(key, cached_data, timeout)
    return cached_data

2. Use the caching function:

def get_cached_object_with_relations(model, pk):
    key = f"{model._meta.model_name}:{pk}"
    cached_data = cache.get(key)

    if cached_data is None:
        try:
            obj = model.objects.get(pk=pk)
            cached_data = cache_object_with_relations(obj)
        except model.DoesNotExist:
            return None

    return cached_data

3. Implement in your views or services:

def my_view(request, object_id):
    cached_data = get_cached_object_with_relations(MyModelA, object_id)
    if cached_data:
        my_model_a = cached_data['main']
        related_b = cached_data['relations'].get('model_b')
        # Use my_model_a and related_b as needed
    else:
        # Handle case when object is not found
    # Rest of your view logic

Key Points

• This approach caches the main object and its first-level related objects together[4][7].
• The cache key is constructed using the model name and primary key[4].
• Related objects are stored in a separate 'relations' dictionary within the cached data[4].
• This method works for ForeignKey, OneToOneField, and ManyToManyField relationships[4].
• The cache timeout is set to 1 hour (3600 seconds) by default, but you can adjust this as needed[4].

Considerations

• Cache Invalidation: Implement a method to invalidate the cache when objects are updated or deleted[4].
• Performance: This approach may increase memory usage but can significantly reduce database queries[4][7].
• Consistency: Ensure that your cache invalidation strategy keeps the cached data consistent with the database[4].

By using this caching strategy, you can efficiently cache Django objects along with their first-level related resources, potentially improving your application's performance by reducing database queries[4][7].

Citations:
[1] https://docs.djangoproject.com/en/5.1/topics/cache/
[2] https://www.honeybadger.io/blog/caching-in-django/
[3] https://buildwithstudio.com/knowledge/a-deepdive-on-caching-strategies-using-django-rest-framework/
[4] https://testdriven.io/blog/django-caching/
[5] https://dev.to/pragativerma18/django-caching-101-understanding-the-basics-and-beyond-49p
[6] https://blog.sentry.io/django-performance-improvements-part-4-caching-in-django-applications/
[7] https://stackoverflow.com/questions/73531279/caching-at-queryset-level-in-django
[8] https://forum.djangoproject.com/t/help-with-caching-related-objects/32266

[delcroip]

to be rework to use the named cache instead