Multiple Data Routers

multiple_db_routers.py

class HulkDataRouter(object):
    """
    A router to control all database operations on models 
    """
    def db_for_read(self, model, **hints):
        if model._meta.app_label in ['goibibo_models', 'goibibo_inbuilt']:
            return 'old_db'
        else:
            return 'hulk_db'
            
    def db_for_write(self, model, **hints):
        if model._meta.app_label == 'goibibo_models':
            return 'old_db'
        elif model._meta.app_label == 'goibibo_inbuilt':
           # avoiding writes to inbuilt types of old_db from HULK
            raise Exception('write not allowed here') 
        else:
            return 'hulk_db'
            
    def allow_migrate(self, db, app_label, model_name=None, **hints):
        if app_label in ['goibibo_models', 'goibibo_inbuilt']:
            return False
        else:
            return True
            
    def allow_relation(self, obj1, obj2, **hints):
        db_list = ('old_db',)
        if obj1._state.db in db_list and obj2._state.db in db_list:
            return True
        return None