Search (module for Omeka S)

Search is a module for Omeka S that adds search capabilities to the public interface of Omeka S, in particular filters and facets. Furthermore, it provides a common interface for other modules to extend it (forms, indexers, queriers).

It can be extended in two ways:

• Forms that will build the search form and construct the query
• Adapters that will do the real work (indexing and querying)

A basic form is provided, with one single main search field without filters, enough in most of the cases for the end uers, especially because the results allow facets. An advanced example of a full form is Psl Search Form, that displays filters for item sets, selected properties, range of dates and map locations. Note: some features of this advanced form are not managed by the internal adapter currently, in particular the queries on a range of dates.

An internal adapter is provided too. It uses the internal Api of Omeka to search resources. There is no indexer currently, and the search engine is the sql one, so it is limited strictly to the request like the standard Omeka S search engine (no wildcards, no management of singular/plural, etc.). Nevertheless, it provides the facets to improve the results. A module is available for Solr, one of the most used search engine.

The Psl search form and the Solr modules were initially built by BibLibre and are used by the digital library of PSL, a French university.

Installation

Uncompress the zip inside the folder modules and rename it Search.

See general end user documentation for Installing a module.

Requirements

• Module jQueryUI for admin interface, to manage the fields used by the form.

Optional dependency

• Module Reference to display facets in the results with the internal adapter. It is not needed for external search engines.

Quick start

The main admin menu Search allows to manage the search indexes and the search pages: an instance of Omeka can contain multiple indexes, for example to hide some fields in the public front-end, and multiple pages, for example a single field search and an advanced search with filters, or different parameters for different sites or different resource types (items or item sets).

An index and a page for the internal adapter are automatically prepared during install. This search engine can be enabled in main settings and site settings. It can be removed too.

To create a new search engine, follow these steps.

1. Create an index
   1. Add a new index with name Internal or whatever you want, using the Internal adapter. The index can be set for items and/or item sets.
   2. The internal adapter doesn’t create any index, so you don’t need to launch the indexation by clicking on the "reindex" button (two arrows forming a circle).
2. Create a page
   1. Add a page named Internal search or whatever you want, a path to access it, for example search or find, the index that was created in the previous step (Internal here), and a form adapter (Basic) that will do the mapping between the form and the index. Forms added by modules can manage an advanced input field and/or filters.
   2. In the page configuration, you can enable/disable facet and sort fields by drag-drop. The order of the fields will be the one that will be used for display. Note that some indexers may have fields that seem duplicated, but they aren’t: some of them allow to prepare search indexes and some other facets or sort indexes. Some of them may be used for all uses. This is not the case for the internal indexer, since there is no index. For example, you can use dcterms:type, dcterms:subject, dcterms:creator, dcterms:date, dcterms:spatial, dcterms:language and dcterms:rights as facets, and dcterms:title, dcterms:date, and dcterms:creator as sort fields. Important: with the internal adapter, the facets work only if the module Reference is enabled.
   3. Edit the name of the label that will be used for facets and sort fields in the same page. The string will be automatically translated if it exists in Omeka.
3. In admin and site settings
   1. To access to the search form, enable it in the main settings (for the admin board) and in the site settings (for the front-end sites). So the search engine will be available in the specified path: https://example.com/s/my-site/search or https://example.com/admin/search in this example.
   2. Optionally, add a custom navigation link to the search page in the navigation settings of the site.

The search form should appear. Type some text then submit the form to display the results as grid or as list. The page can be themed.

IMPORTANT

The Search module does not replace the default search page neither the default search engine. So the theme should be updated.

Search api

The search engine can be used not only for the classical search page, but for any other views too where you the search of items need to be done quickly, for example the block layouts with a big database (more than 10000 to 100000 items, according to your server and your collections).

To use this feature, a page should be created with the form Api. This form is not a true form, but it allows to map the Omeka metadata and properties with the fields indexed by the search engine. It allows to define a max number of results too, that is used when no paginator is enable. The argument limit cannot go further.

When ready, the api search is available via multiple means.

• Add index=1 as query in the block layouts that use it, like Browse preview.
• Do a standard search with $this->api()->search() with the value 'index' => true appended to the argument $data or $options (recommended when possible to avoid to mix the query and the parameters).
• Do a standard search in the theme with the view helpers $this->apiSearch(), and $this->apiSearchOne(), that have the same arguments than $this->api()->search() and $this->api()->searchOne(). The result is an Omeka Response.
• Use the controller plugins $this->apiSearch() and $this->apiSearchOne().
• The main api manager understand these arguments too.
• If the api page form is made available on a site, it will be a quick access to the results at /s/mysite/api_search_page.

Note that some features may be not available in the external search engine. In particular, some events are not triggered.

Indexation

The indexation of items and item sets is automatic and all new metadata can be searched in the admin board. Note that there may be a cache somewhere, and they may be not searchable in the public sites.

So when the item pool of a site or the item sets attached to it are modified, a manual reindexation should be done in the Search board. This job can be done via a cron too (see your system cron).

Furthermore, there may be an indexation delay between the moment when a resource is saved and the moment when it is fully available in the search engine (it may be some minutes with Solr, according to your configuration).

TODO

• Normalize the url query with a true standard (or the Omeka S one, or at the choice of the admin, or the developer of the forms and queriers).
• Make the search arguments groupable to allow smart facets: always display all facets from the original queries, with "or" between facets of the same group, and "and" between groups. Require that the core api allows groups.
• Use the standard view with tabs and property selector for the page creation, in order not to limit it to Dublin Core terms. It will avoid the dependency to the module jQueryUI too. The tabs may be "Filters", "Facets", and "Sort".
• Create an internal index (see Omeka Classic) and move all related code into another module.
• Allow to remove an index without removing pages.
• Allow to import/export a mapping via json, for example the default one.
• Add an option to use the search api by default (and an option 'index' => false).
• Set one api page by site and a quick set in the pages settings.
• Option to forbid default search and advanced search in public front-end.
• Update index when item pool of a site change.
• Genericize and move the value extractor from module Solr to module Search.
• Improve the check of presence of an item in sites for real time indexation.

Warning

Use it at your own risk.

It’s always recommended to backup your files and your databases and to check your archives regularly so you can roll back if needed.

Troubleshooting

See online issues on the module issues page on GitHub.

License

This module is published under the CeCILL v2.1 licence, compatible with GNU/GPL and approved by FSF and OSI.

This software is governed by the CeCILL license under French law and abiding by the rules of distribution of free software. You can use, modify and/ or redistribute the software under the terms of the CeCILL license as circulated by CEA, CNRS and INRIA at the following URL "http://www.cecill.info".

As a counterpart to the access to the source code and rights to copy, modify and redistribute granted by the license, users are provided only with a limited warranty and the software’s author, the holder of the economic rights, and the successive licensors have only limited liability.

In this respect, the user’s attention is drawn to the risks associated with loading, using, modifying and/or developing or reproducing the software by the user in light of its specific status of free software, that may mean that it is complicated to manipulate, and that also therefore means that it is reserved for developers and experienced professionals having in-depth computer knowledge. Users are therefore encouraged to load and test the software’s suitability as regards their requirements in conditions enabling the security of their systems and/or data to be ensured and, more generally, to use and operate it in the same conditions as regards security.

The fact that you are presently reading this means that you have had knowledge of the CeCILL license and that you accept its terms.

Contact

Current maintainers of the module:

• BibLibre (see BibLibre)
• Daniel Berthereau (see Daniel-KM)

Copyright

See commits for full list of contributors.

• Copyright BibLibre, 2016-2017
• Copyright Daniel Berthereau, 2017-2018