Django GeoSource

This django application provide a Rest Framework API that allow to manage many geo data sources and integrate that data wherever you need, like a Django model or any output pipeline. Its provided with necessary celery jobs that do the job.

Settings

You can define the setting GEOSOURCE_MAX_TASK_RUNTIME that allow to define the max run time of a task before it can be launched one more time. It allow to prevent when a task is stuck and disallow launching one more.

Configure and run Celery

You must define in your project settings the variables CELERY_BROKER_URL and CELERY_RESULT_BACKEND as specified in Celery documentation. You also need to create the celery app following this documentation.

Then to run the celery worker: $ celery worker -A django_geosource -l info

To run periodic tasks, use celery beat:

from celery import Celery
from celery.schedules import crontab

app = Celery()

@app.after_finalize.connect
def setup_periodic_tasks(sender, **kwargs):
    # Calls refresh check every 30 minutes
    sender.add_periodic_task(60.0 * 30, run_auto_refresh_source.s())

@app.task
def run_auto_refresh_source():
    from django_geosource.periodics import auto_refresh_source

    auto_refresh_source()

Then run celery beat worker that allow to synchronize periodically sources, launch this command: $ celery beat -A django_geosource -l info

Configure data destination

Now, you must set the callback methods that are used to insert data in your destination database.

If you use django-geostore, we provide a set of callback in the geostore_callbacks module, else you can define your own callbacks.

GEOSOURCE_LAYER_CALLBACK

The callback signature receive as first argument the SourceModel object, and must return your Layer object. Example:

def layer_callback(geosource):
    return Layer.objects.get_or_create(name=geosource.name)[0]

GEOSOURCE_FEATURE_CALLBACK

This one, define a feature creation callback method. Example:

def feature_callback(geosource, layer, identifier, geometry, attributes):
    return Feature.objects.get_or_create(layer=layer, identifier=identifier, geom=geometry, properties=attributes)[0]

GEOSOURCE_CLEAN_FEATURE_CALLBACK

This callback is called when the refresh is done, to clear old features that are not anymore present in the database. It receives as parametter the geosource, layer and begin update date, so you can advise what to do depending of your models. Example:

def clear_features(geosource, layer, begin_date):
    return layer.features.filter(updated_at__lt=begin_date).delete()

GEOSOURCE_DELETE_LAYER_CALLBACK

This is called when a Source is deleted, so you are able to do what you want with the loaded content in database, when the source doesn't exist anymore. It's executed before real deletion. Example:

def delete_layer(geosource, layer):
    if layer.features.count() > 0:
        layer.features.delete()
    return layer.delete()

To start a dev instance

Define settings you wants in test_geosource django project.

docker-compose build
docker-compose up

First start should failed as the database need to be initialized. Just launch the same command twice.

Then initialize the database:

docker-compose run web ./manage.py migrate

You can now edit your code. A django runserver is launched internally so the this is an autoreload server.

You can access to the api on http://localhost:8000/api/

Test and coverage

To run test suite, just launch:

docker-compose run --rm web ./manage.py test

To run test suite with coverage, execute this commande:

docker-compose run web /code/src/coverage.sh