Structure shared raster data across GeoDjango apps?

Question

I currently have a project that consists of multiple webmaps that are written as different apps in a GeoDjango project. The structure of the project is as such:

- project
  - manage.py
  - project
    - settings.py, urls.py, views.py, etc.
  - app1
    - templates, models.py, load.py, urls.py, views.py, etc.
  - app2
    - templates, models.py, load.py, urls.py, views.py, etc.
  - appX
    - templates, models.py, etc.

Each of the apps are focused on particular geographic regions, and are uniquely accessible to members from those regions (e.g., cities within a state) and I don't want to collapse them all into one app. That said, they all use the same raster datasets. At present, new raster tables are built for each app in the app-specific models.py file, and the raster data is split across these tables in the database.

I think it is more efficient to have a project level table that houses all of the raster data -- but am not sure how to do so.

So, rather than having app1_raster, app2_raster, appx_raster tables, I would just have a raster table that all three apps access.

How do I create a project level database table? From what I've seen, documentation encourages one not to do so.

Answer 1

Apps are usually divided for different functionality and not per geographic regions. An example data model could be:

class Zone(models.Model):
    name = models.CharField(...)
    # ... other fields ...

class Placemark(modelf.Model):
    zone = models.ForeignKey(Zone, related_name='placemarks', ...)
    geom = PointField()
    # .... other fields ....

This allows having many zones using one simple code base. Querying for a zone's placemarks is easy as:

# assuming:
my_zone = Zone.objects.get(id=123)
# get the placemarks:
placemarks = my_zone.placemarks.all()

To add rasters-per-zone use

class Raster(modelf.Model):
    zone = models.ForeignKey(Zone, related_name='rasters', ...)
    # .... raster specific other fields ....

This model can be in a rasters app that holds raster-specific functionality.