# Django Tenants Q
Django Tenants Q is a custom implementation for Django-Q cluster for projects that make use Django Tenants package to achieve multi-tenancy in their Django projects with Postgres as database service. Using this package, developer can setup a Django project to be multi-tenant and setup Django-Q cluster to work per tenant/schema basis. This package works with any other broker apart from Django ORM.
> **Note**: This Library is the replica of the library [django-tenant-schemas-q](https://github.com/rajeshyogeshwar/django-tenant-schemas-q)
> Full Credit goes to the author [Rajesh Yogeshwar](https://github.com/rajeshyogeshwar/)
> I have just modified it to work with django_tenants.
# Installation
pip install django-tenants-q
This should install *django-tenants* and *django-q*.
# How to set this up?
As a developer I often find that setting up projects, packages and getting configurations right is sometimes a relatively tough job. In order to make this work nicely, just follow the steps below.
- Refer to settings required by *django_tenants* mentioned [here](https://django-tenants.readthedocs.io/en/latest/install.html)
- Setup *django_tenants* as per the instructions in the above mentioned link. This will take care of setting up of *django_tenants*.
- Add *django_q* to TENANT_APPS setting. This will setup models like Task, Schedule on every tenant post migrations.
- Follow it up with setting up the Django-Q cluster that needs to be run in order to process tasks and run our scheduler.
- While setting up configuration for cluster, **make use of any other broker supported by Django-Q apart from Django ORM.**
- Finally add a setting **SCHEMAS_TO_BE_EXCLUDED_BY_SCHEDULER** in your settings file. The value for this setting is a list of schema that you wish to exclude from scheduler, If not specified, scheduler will exclude a schema by name *public* by default.
# How will this work
Assuming you have followed the instructions perfectly, you should now have settings looking like
SHARED_APPS = ['django_tenants', 'app_containing_tenant_model ', 'any_other_app_needed']
TENANT_APPS = ['django_q', 'standard_django_apps', 'any_other_app_needed']
INSTALLED_APPS = ['django_tenants', 'app_containing_tenant_model', 'django_q', 'standard_django_apps', 'any_other_app_needed']
TENANT_MODEL = 'app_name.ModelName'
SCHEMAS_TO_BE_EXCLUDED_BY_SCHEDULER = ['public']
Q_CLUSTER = {} # Configuration for Q Cluster
What these settings will do is simple. It will simply create *Task & Schedule* models per schema. Django-Q uses these modules to store the tasks and schedules. With these models now setup on per schema/tenant basis the things become a bit cleaner.
To run the cluster, use the command `python manage.py mscluster`
Once the command is fired, the cluster will start and accept the tasks and schedules.
Now, given that are schedules are tasks that are executed as per the frequency having them per schema/tenant basis is something that I wanted to achieve. This would give me ability to configure same tasks with different times and the system will work as expected.
# How to use it
To allow adding a task or schedule with database schema awareness, package contains utilities to make it is seamless.
Add the line `from django_tenants_q.utils import QUtilities` to the line from where you wish to add a `task` or a `schedule`
To add an async task you can use
QUtilities.add_async_task(func_name_as_string, *args, **kwargs)
You can add `sync=True` in kwargs to run the task synchronously.
To create a new schedule you can use
QUtilities.create_schedule(func_name_as_string, *args, **kwargs)
To get a result of a single task
QUtilities.get_result(task_id, wait=0, cached=Conf.CACHED)
To get a result of a group
QUtilities.get_result_group(group_id, failures=False, wait=0, count=None, cached=Conf.CACHED)
To fetch a single task
QUtilities.fetch_task(task_id, wait=0, cached=Conf.CACHED)
To fetch a group of tasks
QUtilities.fetch_task_group(group_id, failures=True, wait=0, count=None, cached=Conf.CACHED)
To get count of groups
QUtilities.get_group_count(group_id, failures=False, cached=Conf.CACHED)
To delete a group of tasks
QUtilities.delete_task_group(group_id, tasks=False, cached=Conf.CACHED)
To delete a task from cache
QUtilities.delete_task_from_cache(task_id, broker=None)
To get the size of the queue
QUtilities.get_queue_size(broker=None)
To add multiple async tasks using Iter
QUtilities.add_async_tasks_from_iter(func, args_iter, **kwargs)
For this use `Iter` from `django_tenants_q.custom` module.
To create a chain of tasks using Chain
QUtilities.create_async_tasks_chain(chain, group=None, cached=Conf.CACHED, sync=Conf.SYNC, broker=None)
For this use `Chain` from `django_tenants_q.custom` module.
# Test the project
There is a test django project in the repository.
- Clone the repository
- Run `docker-compose -f test-compose.yml build`
- Run `docker-compose -f test-compose.yml up -d`
- Run `docker-compose -f test-compose.yml run backend python manage.py setupdata`
- Run `docker-compose -f test-compose.yml run backend python manage.py test --keepdb`
Full credit to authors https://github.com/Koed00 of Django-Q and https://github.com/django-tenants of Django-Tenants for two wonderful packages.