Templating

Within CKAN 2.0 we moved out templating to use Jinja2 from Genshi. This was done to provide a more flexible, extensible and most importantly easy to understand templating language.

Some useful links to get you started.

Legacy Templates

Existing Genshi templates have been moved to the templates_legacy directory and will continue to be served if no file with the same name is located in templates. This should ensure backward compatibility until instances are able to upgrade to the new system.

The lookup path for templates is as follows. Give the template path “user/index.html”:

  1. Look in the template directory of each loaded extension.
  2. Look in the template_legacy directory for each extension.
  3. Look in the main ckan template directory.
  4. Look in the template_legacy directory.

CKAN will automatically determine the template engine to use.

File Structure

The file structure for the CKAN templates is pretty much the same as before with a directory per controller and individual files per action.

With Jinja2 we also have the ability to use snippets which are small fragments of HTML code that can be pulled in to any template. These are kept in a snippets directory within the same folder as the actions that are using them. More generic snippets are added to templates/snippets.

templates/
  base.html             # A base template with just core HTML structure
  page.html             # A base template with default page layout
  header.html           # The site header.
  footer.html           # The site footer.
  snippets/             # A folder of generic sitewide snippets
  home/
    index.html          # Template for the index action of the home controller
    snippets/           # Snippets for the home controller
  user/
    ...
templates_legacy/
  # All ckan templates

Using the templating system

Jinja2 makes heavy use of template inheritance to build pages. A template for an action will tend to inherit from page.html:

{% extends "page.html" %}

Each parent defines a number of blocks that can be overridden to add content to the page. page.html defines majority of the markup for a standard page. Generally only {% block primary_content %} needs to be extended:

{% extends "page.html" %}

{% block page_content.html %}
  <h1>My page title</h1>
  <p>This content will be added to the page</p>
{% endblock %}

Most template pages will define enough blocks so that the extending page can customise as little or as much as required.

Internationalisation

Jinja2 provides a couple of helpers for internationalisation. The most common is to use the _() function:

{% block page_content.html %}
  <h1>{{ _('My page title') }}</h1>
  <p>{{ _('This content will be added to the page') }}</p>
{% endblock %}

Variables can be provided using the “format” function:

{% block page_content.html %}
  <p>{{ _('Welcome to CKAN {name}').format(name=username) }}</p>
{% endblock %}

For longer multiline blocks the {% trans %} block can be used.

{% block page_content.html %}
  <p>
    {% trans name=username %}
      Welcome to CKAN {{ name }}
    {% endtrans %}
  </p>
{% endblock %}

Conventions

There are a few common conventions that have evolved from using the language.

Includes

Note

Includes should be avoided as they are not portable use {% snippet %} tags whenever possible.

Snippets of text that are included using {% include %} should be kept in a directory called _snippets_. This should be kept in the same directory as the code that uses it.

Generally we use the {% snippet %} helper in all theme files unless the parents context must absolutely be available to the snippet. In which case the usage should be clearly documented.

Snippets

Note

{% snippet %} tags should be used in favour of h.snippet()

Snippets are essentially middle ground between includes and macros in that they are includes that allow a specific context to be provided (includes just receive the parent context).

These should be preferred to includes at all times as they make debugging much easier.

Macros

Macros should be used very sparingly to create custom generators for very generic snippets of code. For example macros/form.html has macros for creating common form fields.

They should generally be avoided as they are hard to extend and customise.

Templating within extensions

When you need to add or customize a template from within an extension you need to tell CKAN that there is a template directory that it can call from. Within your update_config method for the extension you’ll need to add a extra_template_paths to the config.

Custom Control Structures

We’ve provided a few additional control structures to make working with the templates easier. Other helpers can still be used using the h object as before.

ckan_extends

{% ckan_extends %}

This works in a very similar way to {% extend %} however it will load the next template up in the load path with the same name.

For example if you wish to remove the breadcrumb from the user profile page in your own site. You would locate the template you wish to override.

ckan/templates/user/read.html

And create a new one in your theme extension.

ckanext-mytheme/ckanext/mytheme/templates/user/read.html

In this new file you would pull in the core template using {% ckan_extends %}:

{% ckan_extends %}

This will now render the current user/read page but we can override any portion that we wish to change. In this case the breadcrumb block.

{% ckan_extends %}

{# Remove the breadcrumb #}
{% block breadcrumb %}{% endblock %}

This function works recursively and so is ideal for extensions that wish to add a small snippet of functionality to the page.

Note

{% ckan_extend %} only extends templates of the same name.

snippet

{% snippet [filepath], [arg1=arg1], [arg2=arg2]... %}

Snippets work very much like Jinja2’s {% include %} except that that do not inherit the parent templates context. This means that all variables must be explicitly passed in to the snippet. This makes debugging much easier.

{% snippet "package/snippets/package_form.html", data=data, errors=errors %}

url_for

{% url_for [arg1=arg1], [arg2=arg2]... %}

Works exactly the same as h.url_for():

<a href="{% url_for controller="home", action="index" %}">Home</a>

url_for_static

{% url_for_static path %}

Works exactly the same as h.url_for_static():

<script src="{% url_for_static "/javascript/home.js" %}"></script>

Form Macros

For working with forms we have provided some simple macros for generating common fields. These will be suitable for most forms but anything more complicated will require the markup to be written by hand.

The macros can be imported into the page using the {% import %} command.

{% import 'macros/form.html' as form %}

The following fields are provided:

form.input()

Creates all the markup required for an input element. Handles matching labels to inputs, error messages and other useful elements.

name        - The name of the form parameter.
id          - The id to use on the input and label. Convention is to prefix with 'field-'.
label       - The human readable label.
value       - The value of the input.
placeholder - Some placeholder text.
type        - The type of input eg. email, url, date (default: text).
error       - A list of error strings for the field or just true to highlight the field.
classes     - An array of classes to apply to the control-group.
attrs       - Dictionary of extra tag attributes
is_required - Boolean of whether this input is required for the form to validate

Examples:

{% import 'macros/form.html' as form %}
{{ form.input('title', label=_('Title'), value=data.title, error=errors.title) }}

form.checkbox()

Builds a single checkbox input.

name        - The name of the form parameter.
id          - The id to use on the input and label. Convention is to prefix with 'field-'.
label       - The human readable label.
value       - The value of the input.
checked     - If true the checkbox will be checked
error       - An error string for the field or just true to highlight the field.
classes     - An array of classes to apply to the control-group.
attrs       - Dictionary of extra tag attributes
is_required - Boolean of whether this input is required for the form to validate

Example:

{% import 'macros/form.html' as form %}
{{ form.checkbox('remember', checked=true) }}

form.select()

Creates all the markup required for an select element. Handles matching labels to inputs and error messages.

A field should be a dict with a “value” key and an optional “text” key which will be displayed to the user. {"value": "my-option", "text": "My Option"}. We use a dict to easily allow extension in future should extra options be required.

name        - The name of the form parameter.
id          - The id to use on the input and label. Convention is to prefix with 'field-'.
label       - The human readable label.
options     - A list/tuple of fields to be used as <options>.
selected    - The value of the selected <option>.
error       - A list of error strings for the field or just true to highlight the field.
classes     - An array of classes to apply to the control-group.
attrs       - Dictionary of extra tag attributes
is_required - Boolean of whether this input is required for the form to validate

Examples:

{% import 'macros/form.html' as form %}
{{ form.select('year', label=_('Year'), options={'value': 2010, 'value': 2011}, selected=2011, error=errors.year) }}

form.textarea()

Creates all the markup required for a plain textarea element. Handles matching labels to inputs, selected item and error messages.

name        - The name of the form parameter.
id          - The id to use on the input and label. Convention is to prefix with 'field-'.
label       - The human readable label.
value       - The value of the input.
placeholder - Some placeholder text.
error       - A list of error strings for the field or just true to highlight the field.
classes     - An array of classes to apply to the control-group.
attrs       - Dictionary of extra tag attributes
is_required - Boolean of whether this input is required for the form to validate

Examples:

{% import 'macros/form.html' as form %}
{{ form.textarea('desc', id='field-description', label=_('Description'), value=data.desc, error=errors.desc) }}

form.markdown()

Creates all the markup required for a Markdown textarea element. Handles matching labels to inputs, selected item and error messages.

name        - The name of the form parameter.
id          - The id to use on the input and label. Convention is to prefix with 'field-'.
label       - The human readable label.
value       - The value of the input.
placeholder - Some placeholder text.
error       - A list of error strings for the field or just true to highlight the field.
classes     - An array of classes to apply to the control-group.
attrs       - Dictionary of extra tag attributes
is_required - Boolean of whether this input is required for the form to validate

Examples:

{% import 'macros/form.html' as form %}
{{ form.markdown('desc', id='field-description', label=_('Description'), value=data.desc, error=errors.desc) }}

form.prepend()

Creates all the markup required for an input element with a prefixed segment. These are useful for showing url slugs and other fields where the input information forms only part of the saved data.

name        - The name of the form parameter.
id          - The id to use on the input and label. Convention is to prefix with 'field-'.
label       - The human readable label.
prepend     - The text that will be prepended before the input.
value       - The value of the input.
              which will use the name key as the value.
placeholder - Some placeholder text.
error       - A list of error strings for the field  or just true to highlight the field.
classes     - An array of classes to apply to the control-group.
attrs       - Dictionary of extra tag attributes
is_required - Boolean of whether this input is required for the form to validate

Examples:

{% import 'macros/form.html' as form %}
{{ form.prepend('slug', id='field-slug', prepend='/dataset/', label=_('Slug'), value=data.slug, error=errors.slug) }}

form.custom()

Creates all the markup required for an custom key/value input. These are usually used to let the user provide custom meta data. Each “field” has three inputs one for the key, one for the value and a checkbox to remove it. So the arguments for this macro are nearly all tuples containing values for the (key, value, delete) fields respectively.

name        - A tuple of names for the three fields.
id          - An id string to be used for each input.
label       - The human readable label for the main label.
values      - A tuple of values for the (key, value, delete) fields. If delete
              is truthy the checkbox will be checked.
placeholder - A tuple of placeholder text for the (key, value) fields.
error       - A list of error strings for the field or just true to highlight the field.
classes     - An array of classes to apply to the control-group.
attrs       - Dictionary of extra tag attributes
is_required - Boolean of whether this input is required for the form to validate

Examples:

{% import 'macros/form.html' as form %}
{{ form.custom(
     names=('custom_key', 'custom_value', 'custom_deleted'),
     id='field-custom',
     label=_('Custom Field'),
     values=(extra.key, extra.value, extra.deleted),
     error='')
}}

form.autoform()

Builds a form from the supplied form_info list/tuple.

form_info       - A list of dicts describing the form field to build.
data            - The form data object.
errors          - The form errors object.
error_summary   - The form errors object.

Example

{% set form_info = [
    {'name': 'ckan.site_title', 'control': 'input', 'label': _('Site Title'), 'placeholder': ''},
    {'name': 'ckan.main_css', 'control': 'select', 'options': styles, 'label': _('Style'), 'placeholder': ''},
    {'name': 'ckan.site_description', 'control': 'input', 'label': _('Site Tag Line'), 'placeholder': ''},
    {'name': 'ckan.site_logo', 'control': 'input', 'label': _('Site Tag Logo'), 'placeholder': ''},
    {'name': 'ckan.site_about', 'control': 'markdown', 'label': _('About'), 'placeholder': _('About page text')},
    {'name': 'ckan.site_intro_text', 'control': 'markdown', 'label': _('Intro Text'), 'placeholder': _('Text on home page')},
    {'name': 'ckan.site_custom_css', 'control': 'textarea', 'label': _('Custom CSS'), 'placeholder': _('Customisable css inserted into the page header')},
    ] %}

{% import 'macros/form.html' as form %}
{{ form.autoform(form_info, data, errors) }}