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FacetHandler
service in module seco.facetedSearch

Description

Service for mediating the communication between facets.

When created, the FacetHandler object broadcasts a sf-initial-constraints event on the given scope, with the following structure:

  • constraint - {Array} - The constraints as generated by all the facets, plus any initial constraints defined in the init configuration.
  • facets - {Object} - A collection of facet states where the key is the facetId of the facet, and value is the state as emitted by that facet.
  • config - {Object} - The configuration given when instantiating the FacetHandler.

The FacetHandler object listens for two events:

  • sf-request-constraints - In response will broadcast a sf-initial-constraints event with the same object as above as the argument.
  • sf-facets-changed - In response will broadcast a sf-facet-constraints event on the scope with the same object as above, except omitting config.

The event names are injectable as constants:

  • sf-initial-constraints: EVENT_INITIAL_CONSTRAINTS
  • sf-facet-constraints: EVENT_FACET_CONSTRAINTS
  • sf-request-constraints: EVENT_REQUEST_CONSTRAINTS
  • sf-facet-changed: EVENT_FACET_CHANGED

Usage

new FacetHandler(config);

Parameters

ParamTypeDetails
configObject

Configuration object broadcast to all facets at init. The object has the following properties:

  • scope - {Object} - The facets' parent scope. This is used for broadcasting and listening for events.
  • [endpointUrl] - {string} - The SPARQL endpoint URL. Optional, as it is just sent to all listening facets at init, and can also be given to facets individually.
  • [headers] {Object} - Additional HTTP headers.
  • [constraint] - {string} - A SPARQL triple pattern that selects all the resources that are being faceted.
  • [rdfClass] - {string} - The rdf:type of the resources being faceted. A shorthand for constraint: '?id a <class> .'.
  • [preferredLang] - {string|Array} - The language tag that is preferred when getting labels for facet values, in case the value is a resource. If the value is an Array, the specified languages are tried in order. The default is 'en'. This argument can also be given directly to the individual facets.
  • [initialState] - {Object} - The initial state of the facets. Used when loading the state from URL parameters, for example. See facetUrlStateHandlerService.

The object is sent to facets as is, and so any extra fields will be included, although the above fields are the only ones used by FacetHandler and the built-in facets.

Methods