Presentation by Burak Karaboğa Software Engineer, Atos FIWARE Tech Summit 28-29 November, 2017 Malaga, Spain

1. Empower Your CKAN:
How to Implement CKAN Extensions
Burak Karaboga – Atos Research & Innovation

2. CKAN Extensions?
§ A Python package that modifies or extends CKAN
§ Extension = One or more plugins
§ For example: datastore, datapusher, disqus etc.
§ Extension catalogue¹
[1] http://extensions.ckan.org
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3. Prerequisites
§ Source installation of CKAN
§ Basic Python knowledge
§ Patience
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4. Our goals
§ Modify a core functionality
§ Change and restrict group creation process
§ Extend the default application
§ Add a new UI element to the organizations page
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5. Assumptions
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§ By default, only system admins can create groups
§ For the sake of this tutorial, we assume everyone can
§ If you like, you can configure your CKAN to reflect this
ckan.auth.user_create_groups = true

6. Let’s start
§ Run the paster command
§ Creates an empty extension from template
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$ . /usr/lib/ckan/default/bin/activate
$ cd /usr/lib/ckan/default/src
$ paster --plugin=ckan create -t ckanext ckanext-fiwaredemo

7. What do we have?
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ckanext-fiwaredemo/
|____ setup.py
|____ ckanext_iauthfunctions.egg-info/
|____ ckanext/
|____ __init__.py
|____ plugin.py
|____ fiwaredemo/
|____ __init__.py
|____ fantastic/
|____ i18n/
|____ public/
|____ templates/
|____ tests/
|____ test_plugin.py

8. Activate the plugin
§ setup.py
§ development.ini
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entry_points, ='''
[ckan.plugins]
fiwaredemo=ckanext.iauthfunctions.plugin:FiwaredemoPlugin
'''
ckan.plugins = stats text_view recline_view fiwaredemo

9. Modifying group logic
§ We have 2 steps:
1) Disallow creation of CKAN groups
2) Only allow the members of a group called “Curators” to create
CKAN groups
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10. plugin.py | initial state
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class FiwaredemoPlugin(plugins.SingletonPlugin):
plugins.implements(plugins.IConfigurer)
# IConfigurer
def update_config(self, config_):
toolkit.add_template_directory(config_, 'templates')
toolkit.add_public_directory(config_, 'public')
toolkit.add_resource('fanstatic', 'fiwaredemo')

11. plugin.py | restricting access
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def group_create(context, data_dict=None):
return {'success': False, 'msg': 'No one is allowed to create groups'}
class FiwaredemoPlugin(plugins.SingletonPlugin):
plugins.implements(plugins.IConfigurer)
plugins.implements(plugins.IAuthFunctions)
# IConfigurer
def update_config(self, config_):
toolkit.add_template_directory(config_, 'templates')
toolkit.add_public_directory(config_, 'public')
toolkit.add_resource('fanstatic', 'fiwaredemo')
# IAuthFunctions
def get_auth_functions(self):
return {'group_create': group_create}

12. plugin.py | getting smarter
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def group_create(context, data_dict=None):
user_name = context['user']
members = toolkit.get_action('member_list')(data_dict={'id': 'curators', 'object_type': 'user'})
member_ids = [member_tuple[0] for member_tuple in members]
convert_user_name_or_id_to_id = toolkit.get_converter('convert_user_name_or_id_to_id')
user_id = convert_user_name_or_id_to_id(user_name, context)
if user_id in member_ids:
return {'success': True}
else:
return {'success': False,
'msg': 'Only curators are allowed to create groups'}

13. Extending Organizations Page
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§ We have 4 steps:
1) Create the route for the new page
2) Extend the existing CKAN template
3) Add a new template
4) Create a controller

14. plugin.py | adding the route
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class FiwaredemoPlugin(plugins.SingletonPlugin):
plugins.implements(plugins.IConfigurer)
plugins.implements(plugins.IAuthFunctions)
plugins.implements(plugins.IRoutes)
# IRoutes
def before_map(self, map):
with SubMapper(map, controller='ckanext.fiwaredemo.controller:FiwaredemoController') as m:
m.connect('ckanext_fiwaredemo_users', '/organization/users/{id}', action='users',
ckan_icon='users')
return map
# IConfigurer
def update_config(self, config_):
toolkit.add_template_directory(config_, 'templates')
toolkit.add_public_directory(config_, 'public')
toolkit.add_resource('fanstatic', 'fiwaredemo')
# IAuthFunctions
def get_auth_functions(self):
return {'group_create': group_create}

15. CKAN templates
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§ CKAN UI extension with templates
§ {% extends “page.html” %}
§ {% ckan_extends %}
§ Rule: same path, same name

16. CKAN templates | read_base.html
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{% extends "page.html" %}
...
{% block content_primary_nav %}
{{ h.build_nav_icon('organization_read', _('Datasets'), id=c.group_dict.name) }}
{{ h.build_nav_icon('organization_activity', _('Activity Stream'), id=c.group_dict.name, offset=0) }}
{{ h.build_nav_icon('organization_about', _('About'), id=c.group_dict.name) }}
{% endblock %}
...
ckan/templates/organization/read_base.html

17. CKAN templates | read_base.html
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{% ckan_extends %}
...
{% block content_primary_nav %}
{{ super() }}
{{ h.build_nav_icon('ckanext_fiwaredemo_users', _('Users'), id=c.group_dict.name) }}
{% endblock %}
...
ckanext-fiwaredemo/ckanext/fiwaredemo/templates/organization/read_base.html

18. Organizations page
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19. CKAN templates | users.html
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{% extends "organization/read_base.html" %}
{% block subtitle %}{{ _('Users') }} - {{ super() }}{% endblock %}
{% block primary_content_inner %}
<h2 class="hide-heading">{% block page_heading %}{{ _('Users') }}{% endblock %}</h2>
<h3 class="page-heading">{{ _('{0} member(s)'.format(c.members|length)) }}</h3>
<table class="table table-header table-hover table-bordered" id="member-table">
<thead>
<tr>
<th>{{ _('User') }}</th>
<th>{{ _('Role') }}</th>
</tr>
</thead>
<tbody>
{% for user_id, user, role in c.members %}
<tr>
<td class="media">
{{ h.linked_user(user_id, maxlength=20) }}
</td>
<td>{{ role }}</td>
</tr>
{% endfor %}
</tbody>
</table>
{% endblock %}

20. controller.py
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class FiwaredemoController(OrganizationController):
def users(self, id):
group_type = self._ensure_controller_matches_group_type(id)
context = {'model': model, 'session': model.Session,
'user': c.user}
try:
data_dict = {'id': id}
#check_access('group_edit_permissions', context, data_dict)
c.members = self._action('member_list')(
context, {'id': id, 'object_type': 'user'}
)
data_dict['include_datasets'] = False
c.group_dict = self._action('group_show')(context, data_dict)
except NotFound:
abort(404, _('Group not found'))
#except NotAuthorized:
# abort(403, _('User %r not authorized to edit members of %s') % (c.user, id))
return self._render_template('organization/users.html', group_type)

21. Organization Users
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22. What’s next?
§ Source code: https://github.com/McMutton/ckanext-fiwaredemo
§ Official documentation
§ Tutorial: http://docs.ckan.org/en/latest/extensions/tutorial.html
§ Extension guide: http://docs.ckan.org/en/latest/extensions/index.html
§ Examples: https://github.com/ckan/ckan/tree/master/ckanext
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23. Thank you!
http://fiware.org
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