logo CKAN Extensions

CKAN extension for graph views, with data processing moved to the backend
by U.K. Natural History Museum

ckanext-graph

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A CKAN extension that adds a graph view for resources.

Overview

Adds graph views for resources on a CKAN instance. Two types of graph are available: temporal (a line graph showing count over time based on a specified date field), and categorical (a bar chart showing counts for various values in a specified field).

NB: the current version of this extension only works with the Natural History Museum’s ElasticSearch datastore CKAN backend. However, it is designed to be extensible, so if you would like to use this extension with a different backend (e.g. the standard PostgreSQL datastore), please see the Extending section.

Installation

Path variables used below:

  • $INSTALL_FOLDER (i.e. where CKAN is installed), e.g. /usr/lib/ckan/default
  • $CONFIG_FILE, e.g. /etc/ckan/default/development.ini
  1. Clone the repository into the src folder:
cd $INSTALL_FOLDER/src
git clone https://github.com/NaturalHistoryMuseum/ckanext-graph.git
  1. Activate the virtual env:
. $INSTALL_FOLDER/bin/activate
  1. Install the requirements from requirements.txt:
cd $INSTALL_FOLDER/src/ckanext-graph
pip install -r requirements.txt
  1. Run setup.py:
cd $INSTALL_FOLDER/src/ckanext-graph
python setup.py develop
  1. Add ‘graph’ to the list of plugins in your $CONFIG_FILE:
ckan.plugins = ... graph

Configuration

There is currently only one option that can be specified in your .ini config file.

Name Description Options Default
ckanext.graph.backend The name of the backend to use (currently only elasticsearch is implemented) elasticsearch, sql elasticsearch

Usage

Templates

The view will be added as an option with no further configuration necessary. However, if you wish to override or add content to the template, you can extend templates/graph/view.html:

{% ckan_extends %}

{% block my_new_block %}
  <p>Look, some exciting new content.</p>
{% endblock %}

Extending

To use this extension with a datastore backend other than the ElasticSearch backend already implemented, you’ll have to subclass from Query in ckanext-graph/ckanext/graph/db.py.

An unimplemented class for SQL queries is already in the file as an example:

class SqlQuery(Query):
    @property
    def _date_query(self):
        raise NotImplementedError()

    @property
    def _count_query(self):
        raise NotImplementedError()

    def run(self):
        raise NotImplementedError()

If you add a new class, you’ll have to add it to the dictionary in Query.new() method to make it available as a configurable option.

If you do this, please submit a pull request! Contributions are always welcome.

Testing

Test coverage is currently extremely limited.

To run the tests in this extension, there is a Docker compose configuration available in this repository to make it easy.

To run the tests against ckan 2.9.x on Python2:

  1. Build the required images
docker-compose build
  1. Then run the tests. The root of the repository is mounted into the ckan container as a volume by the Docker compose configuration, so you should only need to rebuild the ckan image if you change the extension’s dependencies.
docker-compose run ckan

The ckan image uses the Dockerfile in the docker/ folder which is based on openknowledge/ckan-dev:2.9-py2.

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