Question

I have multiple Django models that reference a model using foreign keys as such:

class LocationHistory(models.Model):
    region = models.ForeignKey(WorldGrid)
    ...

class UserSynthVals(models.Model):
    region = models.ForeignKey(WorldGrid)
    ...

class RegionalVictoryRate(models.Model):
    region = models.ForeignKey(WorldGrid)
    ...

Where WorldGrid is just:

class WorldGrid(models.Model):
    latitude = models.FloatField()
    longitude = models.FloatField()
    ...

Now, I am able to get all the models that reference WorldGrid (abstractly for reusability) with:

models_that_reference = [i.model for i in get_model('appname',model_name)._meta.get_all_related_objects()]

And at that point I can loop through them getting their model.objects.all().values(), but I cannot find a way to join those separate lists of objects into one that I could then output to a table.

I would rather do something more along the lines of django’s expected use (like what select_related() does) and keep this abstract.

Any help solving this problem would be appreciated, or a new direction to try.

Answer 1

I was able to find a pretty good way of doing this, and the select_related was indeed the key. Once I have a list of the referencing models, I can do:

fields_that_reference = [[m._meta.object_name.lower()+'__'+f.name for f in m._meta.fields if not isinstance(f,related.ForeignKey) ] for m in models_that_reference]

for i in fields_that_reference:
    fields +=i

To get all of the fields that I am trying to see at once, and then:

all_objects = get_model('appname',model_name).objects.select_related().values(*fields)

To get them all into one giant list. If your models are historic (with datetime fields), or have circular foreignkeys, you will probably need to prune this result a little more before displaying it, but this gets everything together nicely.