Data migration using RunPython

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I am working on a data migration for my Django app to populate
the main table in the db with data that will form the mainstay of
the app - this is persistent/permanent data that may added to but
never deleted.

My reference is the Django 1.7 documentation and in particular an
example on page

https://docs.djangoproject.com/en/1.7/ref/migration-operations/#django.db.migrations.operations.RunPython

with a custom method called forward_funcs:

def forwards_func(apps, schema_editor):

# We get the model from the versioned app registry;
# if we directly import it, it'll be the wrong version


Country = apps.get_model("myapp", "Country")
db_alias = schema_editor.connection.alias
Country.objects.using(db_alias).bulk_create([
Country(name="USA", code="us"),
Country(name="France", code="fr"),])

I was wondering if someone could please explain what is happening
here and how this method works - is the argument to bulk_create a
list of namedtuple objects called Country or are these Country model
objects?

Also could someone please explain what db_alias is?

Sandeep


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