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Enabling Common Resource Preview Tools
The CKAN resource page can contain one or more visualizations of the resource data or file contents (a table, a bar chart, a map, etc). These are commonly referred to as resource views. Different view types are implemented via custom plugins, which can be activated on a particular CKAN site. Enable resource views by editing the ckan.plugins property in the CKAN config file (production.ini found at /etc/ckan/default/production.ini) as shown below and restart CKAN:
ckan.plugins = [...] image_view recline_view pdf_view [...]
The main features of resource views are:
- One resource can have multiple views of the same data (for example a grid and some graphs for tabular data).
- Dataset editors can choose which views to show, reorder them, and configure them individually.
- Individual views can be embedded on external sites.
Whether a particular resource can be rendered by the different view plugins is decided by the view plugins themselves. This is generally done checking the resource format or whether its data is on the DataStore extension or not.
From the management interface, you can create and edit views manually, to automatically create resource types whenever a new resource is created/updated, add them by editing the ckan.views.default_views property in the CKAN config file (production.ini found at /etc/ckan/default/production.ini) as shown below and restart CKAN:
ckan.views.default_views = [...] recline_view pdf_view geojson_view [...]
Below is a description of how to set up some common resource preview formats. Some do not require further setup and can be directly added to the ckan.plugins setting without necessarily installing custom plugins.
Displays files in XML, JSON or plain text based formats with the syntax highlighted. The formats detected can be configured using the ckan.preview.xml_formats, ckan.preview.json_formats and ckan.preview.text_formats configuration options respectively.
If you want to display files that are hosted in a different server from your CKAN instance (e.g that haven’t been uploaded to CKAN) you will need to enable the Resource Proxy plugin.
Enable the text resource views by adding text_view plugin to CKAN's ckan.plugins configuration key in /etc/ckan/default/production.ini as shown below and restart CKAN:
ckan.plugins = [...] text_view [...]
If the resource format is a common image format like PNG, JPEG, or GIF, it adds <img> tags pointing to the resource URL. You can provide an alternative URL on the edit view form. The available formats can be configured using the ckan.preview.image_formats configuration option.
Enable the image resource views by adding image_view plugin to CKAN's ckan.plugins configuration key in /etc/ckan/default/production.ini as shown below and restart CKAN:
ckan.plugins = [...] image_view [...]
Adds <iframe> tags to embed the resource URL. You can provide an alternative URL on the edit view form.
Enable the web page resource views by adding webpage_view plugin to CKAN's ckan.plugins configuration key in /etc/ckan/default/production.ini as shown below then restart:
ckan.plugins = [...] webpage_view [...]
Renders PDF resources using PDF.js. Enable PDF resource view by following the steps described below:
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Activate CKAN's virtual environment
. /usr/lib/ckan/default/bin/activate -
Install ckanext-pdfview
$ pip install ckanext-pdfview -
Add
pdf_viewto theckan.pluginssetting in your CKAN config file (production.inifound at/etc/ckan/default/production.ini) as shown below and restart CKAN:ckan.plugins = [...] pdf_view [...]
If you want to render PDF files that are not located in the same server as CKAN you also need to enable the resource_proxy plugin.
Adds a rich widget, based on the Recline Javascript library. It allows querying, filtering, graphing, and mapping data. The Data Explorer is optimized for displaying structured data hosted on the DataStore extension.
The Data Explorer can also display certain formats of tabular data (CSV and Excel files) without its contents being uploaded to the DataStore. This is done via the DataProxy, an external service that will parse the contents of the file and return a response that the view widget understands. However, as the resource must be downloaded by the DataProxy service and parsed before it is viewed, this option is slower and less reliable than viewing data that is in the DataStore. It also does not properly support different encodings, proper field type detection, etc so users are strongly encouraged to host data on the DataStore instead.
Enable the data explorer resource views by adding recline_view to the ckan.plugins setting in your CKAN config file (production.ini found at /etc/ckan/default/production.ini) as shown below and restart CKAN:
ckan.plugins = [...] recline_view [...]
Displays a filterable, sortable, table view of structured data. This plugin requires data to be in the DataStore.
Enable the datastore grid resource views by adding recline_grid_view to the ckan.plugins setting in your CKAN config file (production.ini found at /etc/ckan/default/production.ini) as shown below and restart CKAN:
ckan.plugins = [...] recline_grid_view [...]
Allows creating graphs from data stored on the DataStore. You can choose the graph type (such as lines, bars, columns, etc) and restrict the displayed data, by filtering by a certain field value or defining an offset and the number of rows. This plugin requires data to be in the DataStore.
Enable the datastore graph resource views by adding recline_graph_view to the ckan.plugins setting in your CKAN config file (production.ini found at /etc/ckan/default/production.ini) as shown below and restart CKAN:
ckan.plugins = [...] recline_graph_view [...]
Shows data stored on the DataStore in an interactive map. It supports plotting markers from a pair of latitude/longitude fields or from a field containing a GeoJSON representation of the geometries. The configuration also allows to cluster markers if there is a high density of them and to zoom automatically to the rendered features. This plugin requires data to be in the DataStore.
There is partial support to change the map tiles to a different service, such as Mapbox. Look below for an example to add to your configuration file:
# Mapbox example:
ckanext.spatial.common_map.type = mapbox
ckanext.spatial.common_map.mapbox.map_id = <id>
ckanext.spatial.common_map.mapbox.access_token = <token>
ckanext.spatial.common_map.attribution=© <a target=_blank href='https://www.mapbox.com/map-feedback/'>Mapbox</a> © <a target=_blank
href='http://www.openstreetmap.org/copyright'>OpenStreetMap</a>
ckanext.spatial.common_map.subdomains = <subdomains>
# Custom example:
ckanext.spatial.common_map.type = custom
ckanext.spatial.common_map.custom.url = <url>
ckanext.spatial.common_map.custom.tms = <tms>
ckanext.spatial.common_map.attribution = <copyright link>
ckanext.spatial.common_map.subdomains = <subdomains>
Enable the datastore map resource views by adding recline_map_view to the ckan.plugins setting in your CKAN config file (production.ini found at /etc/ckan/default/production.ini) as shown below and restart CKAN:
ckan.plugins = [...] recline_map_view [...]
As resource views are rendered on the browser, if the file they are accessing is located in a different domain than the one CKAN is hosted, the browser will block access to it because of the same-origin policy. For instance, files hosted on www.example.com won’t be able to be accessed from the browser if CKAN is hosted on data.catalog.com.
To allow view plugins access to external files you need to activate the resource_proxy plugin on your configuration file:
Enable the resource proxy by adding resource_proxy to the ckan.plugins setting in your CKAN config file (production.ini found at /etc/ckan/default/production.ini) as shown below:
ckan.plugins = [...] resource_proxy [...]