A collection in Liara groups content together into an optionally ordered collection. This grouping is efficient, i.e. iterating a sorted collection does not incur any sorting cost. It is also efficient to look up the next/previous entry in an collection.
A collection definition consists of the following elements:
The name (that’s the key used in the YAML file)
filter: The filter – this is an URL pattern which defines all elements that are in this collection.
order_by: The ordering – optionally specifies how the collection should be ordered. This is a metadata accessor, to access nested fields, separate the individual accesses using
.. For instance,
date.yearwill access the
datemetadata field first, and then the
yearattribute. If you want to reverse the order, add a leading
-, for example
-date.year. If the metadata is missing, an error will be raised. Use
exclude_withoutif you want to remove items which don’t have certain metadata fields. Multiple fields can be specified by using a list.
exclude_without: Optionally exclude nodes without the specified metadata field(s). Multiple fields can be specified by using a list.
node_kinds: The node kinds to include – optionally, the kinds of nodes to include in the collection can be specified. If nothing is specified, only document nodes are included by default.
blog: filter: '/blog/**' order_by: 'date' exclude_without: 'date'
Defines a collection named
blog, which contains all elements under
/blog, ordered by the
date metadata field. Documents which don’t contain a
date metadata entry are filtered out.
exclude_without filter, documents without a
date metadata field would cause an error.
Collections can be used in two places, templates and indices. In a template, you can retrieve all pages in a collection by using using
get_collection(). This returns a
Query object which can be used to iterate over the set of pages. If a collection is ordered,
get_previous_in_collection() can be used to provide next/previous links for documents which are part of a collection.
The other use of collections is to create an index. See Indices for more details.