Kerko 1.0.0a2

A Flask blueprint that provides a faceted search interface for bibliographies based on Zotero.

Kerko

Kerko is a web application component that provides a user-friendly search and browsing interface for sharing a bibliography managed with the Zotero reference manager.

The combination of Kerko and Zotero gives you the best of both worlds: a rich but easy to use web interface for end-users of the bibliography, and a well-established and powerful bibliographic reference management tool for individuals or teams working on the bibliography's content.

Demo site

A KerkoApp-based demo site is available for you to try. You may also view the Zotero library that contains the source data for the demo site.

Powered by Kerko

The following sites are powered by Kerko:

• Bibliographie francophone sur l'archivistique
• Community Knowledge Open Library on English-Speaking Quebec
• Lipedema Foundation LEGATO Lipedema Library
• Open Development & Education Evidence Library
• The EdTech Hub Evidence Library
• University of Saint Joseph Research Output

Features

The main features provided by Kerko are:

• Faceted search interface: allows exploration of the bibliography both in search mode and in browsing mode, potentially suiting different user needs, behaviors, and abilities. For example, users with a prior idea of the topic or expected results may enter keywords or a more complex query in a search field, while those who wish to become familiar with the content of the bibliography or discover new topics may choose to navigate along the proposed facets, to narrow or broaden their search. Since both modes are integrated into a single interface, it is possible to combine them.
• Keyword search features:
  • Boolean operators:
    • AND: matches items that contain all specified terms. This is the default relation between terms when no operator is specified, e.g., a b is the same as a AND b.
    • OR: matches items that contain any of the specified terms, e.g., a OR b.
    • NOT: excludes items that match the term, e.g., NOT a.
    • Boolean operators must be specified in uppercase and may be translated in other languages.
  • Logical grouping (with parentheses), e.g., (a OR b) AND c.
  • Sequence of words (with double quotes), e.g., "a b c". The default difference between word positions is 1, meaning that an item will match if it contains the words next to each other, but a different maximum distance may be selected (with the tilde character), e.g. "web search"~2 allows up to 1 word between web and search, meaning it could match web site search as well as web search.
  • Term boosting (with the caret), e.g., faceted^2 search browsing^0.5 specifies that faceted is twice as important as search when computing the relevance score of results, while browsing is half as important. Boosting may be applied to a logical grouping, e.g., (a b)^3 c.
  • Keyword search is case-insensitive, accents are folded, and punctuation is ignored. To further improve recall (albeit at the cost of precision), stemming is also performed on terms from most text fields, e.g., title, abstract, notes. Stemming relieves the user from having to specify all variants of a word when searching, e.g., terms such as search, searches, and searching all return the same results. The Snowball algorithm is used for that purpose.
  • Full-text search: the text content of PDF attachments can be searched.
  • Scope of search: users may choose to search everywhere, in author/contributor names, in titles, in all fields (i.e., in metadata and notes), or in documents (i.e., in the text content of attachments). Applications may provide additional choices.
• Faceted browsing: allows filtering by topic (Zotero tag), by resource type (Zotero item type), by publication year. Moreover, you may define additional facets modeled on collections and subcollections; in such case, any collection can be represented as a facet, and each subcollection as a value within that facet. By taking advantage of Zotero's ability to assign any given item to multiple collections, a faceted classification scheme can be designed, including hierarchical subdivisions within facets.
• Relevance scoring: provided by the Whoosh library and based on the BM25F algorithm, which determines how important a term is to a document in the context of the whole collection of documents, while taking into account its relation to document structure (in this regard most fields are neutral, but the score is boosted when a term appears in specific fields, e.g., DOI, ISBN, ISSN, title, author/contributor). Any keyword search asks the question "how well does this document match this query clause?", which requires calculating a relevance score for each document. Filtering with facets, on the other hand, has no effect on the score because it asks "does this document match this query clause?", which leads to a yes or no answer.
• Sort options: by relevance score (only applicable to keyword search), by publication date, by author, by title.
• Citation styles: any from the Zotero Style Repository, or custom stylesheet defined in the Citation Style Language (stylesheet must be accessible by URL).
• Language support: the default language of the user interface is English, but some translations are provided. Additional translations may be created using gettext-compatible tools. Also to consider: locales supported by the Zotero Data Schema (which provides the names of fields, item types and author types displayed by Kerko); languages supported by Whoosh (which provides the search capabilities), i.e., ar, da, nl, en, fi, fr, de, hu, it, no, pt, ro, ru, es, sv, tr.
• Semantic markup: pages generated by Kerko embed HTML markup that can be detected by web crawlers (helping the indexing of your records by search engines) or by web browsers (allowing users of reference management tools to easily import metadata in their library). Supported schemes are:
  • OpenURL COinS, in search results pages and individual bibliographic record pages. COinS is recognized by many reference management tools, including the Zotero Connector browser extension.
  • Highwire Press tags, in the individual bibliographic record pages of book, conference paper, journal article, report or thesis items. These tags are recommended for indexing by [Google Scholar][HighwirePress_Google], and are recognized by many other databases and reference management tools, including the Zotero Connector browser extension.
• Web feeds: users of news aggregators or feed readers may get updates when new bibliographic records are added. They may subscribe to the main feed, or to one or more custom feeds.
  • The main feed lists the most recently added bibliographic records.
  • Any search page has a related custom feed that lists the most recently added bibliographic records that match the search criteria. Thus, a user can obtain a custom feed for a particular area of interest simply by entering keywords to search and/or selecting filters.
  • Feeds are provided in the Atom syndication format.
  • Basic metadata is provided directly in the feeds, using both Atom and unqualified Dublin Core elements.
  • An age limit may be configured to exclude older items from the feeds. This may be useful to bibliographies that are frequently updated and mostly meant to promote recent literature (all resources still remain visible to the search interface regardless of their age).
• Sitemap: an XML Sitemap is automatically generated, and you may use it to help search engines discover your bibliographic records.
• Exporting: users may export individual records as well as complete bibliographies corresponding to search results. By default, download links are provided for the RIS and BibTeX formats, but applications may be configured to export any format supported by the Zotero API.
• Printing: stylesheets are provided for printing individual bibliographic records as well as lists of search results. When printing search results, all results get printed (not just the current page of results).
• Notes and attachments: notes, attached files, and attached links to URIs are synchronized from zotero.org and made available to users of the bibliography. Regular expressions may be used to include or exclude such child items from the bibliography, based on their tags.
• DOI, ISBN and ISSN resolver: items that have such identifier in your library can be referenced by appending their identifier to your Kerko site's base URL.
• Relations: bibliographic record pages show links to related items, if any. You may define such relations using Zotero's Related field. Moreover, Kerko adds the Cites and Cited by relation types, which can be managed in Zotero through notes. Custom applications can add more types of relations if desired.
• Badges: custom applications can have icons conditionally displayed next to items.
• Responsive design: the simple default implementation works on large monitors as well as on small screens. It is based on Bootstrap.
• Google Analytics integration: just provide a Google Analytics stream ID to have Kerko automatically include the tracking code into its pages.
• Integration: as a Flask blueprint, Kerko can be integrated into any Flask application. For a standalone application, however, you may simply install KerkoApp.
• Customizable front-end: applications may partly or fully replace the default templates, scripts and stylesheets with their own.
• Command line interface (CLI): Kerko provides commands for synchronizing or deleting its data.

KerkoApp is a standalone application built around Kerko. It inherits all of Kerko's features and it provides a few additions of its own:

• Configuration files: allow separation of configuration from code and enable the Twelve-factor App methodology. Environment variables and TOML configuration files are supported. Secrets, server-specific parameters, and general parameters can be configured in separate files.
• Page templates for common HTTP errors.
• Syslog logging handler (for Unix environments).

Learn more

Please refer to the documentation for more details.

Changelog

1.0.0alpha2 (2023-07-12)

Features:

• Add new configuration parameters kerko.link_groups.*. for defining sets of links that may be used for navigation.
• Add a breadcrumb trail to all pages. One or more base links can be configured (see configuration parameters kerko.breadcrumb and kerko_link_groups.breadcrumb_base).

Bug fixes:

• Fix validation pattern too restrictive for the kerko.zotero.csl_style configuration parameter.

Backwards incompatible changes:

• Items from the main navigation bar are now based on the kerko.link_groups.navbar configuration. There is no default translation for it. To change the default text or to translate it, you must override the default kerko.link_groups.navbar in your configuration file. If you have overridden the _navbar_items.html.jinja2 template and wish to use the configuration, you might want to adapt it, or revert to the default template.

Other changes:

• Improve documentation.

1.0.0alpha1 (2023-06-29)

Features:

• Add the --full option to the sync command line interface (CLI) command.

Bug fixes:

• Fix validation pattern too restrictive for the kerko.facets.*.collection_key configuration parameter.
• Fix incorrect typing for the kerko.features.download_results_max_count and kerko.features.print_results_max_count configuration parameters.

Other changes:

• Rename the default branch of the repository from 'master' to 'main'. If you have cloned the repository with Git, use the following commands to rename your local branch:

  git branch -m master main
  git fetch origin
  git branch -u origin/main main
  git remote set-head origin -a
  

• Make the config CLI command show the configuration in TOML format.

• Make the config CLI command hide secrets by default. Add a --show-secrets option.

• Improve documentation.

Backwards incompatible changes:

• Prevent the clean CLI command from cleaning everything by default. To delete everything, you now have to run flask kerko clean everything. This may help accidental deletion of the cache or the search index, which in some instances can take long to rebuild.
• Rename the following configuration parameters:
  • kerko.citation_formats.* → kerko.bib_formats.*.
  • kerko.features.download_citations_link → kerko.features.download_results_link
  • kerko.features.download_citations_max_count → kerko.features.download_results_max_count
  • kerko.features.print_citations_link → kerko.features.print_results_link
  • kerko.features.print_citations_max_count → kerko.features.print_results_max_count
• Rename the following views:
  • item_citation_download → item_bib_download
  • search_citation_download → search_bib_download

1.0.0alpha0 (2023-06-26)

Warning: Upgrading from version 0.9 or earlier will require that you adapt your installation and configuration files, then rebuild your search index. Use the commands below, then restart the application. If you are using KerkoApp, make sure to check its changelog.

flask kerko clean index
flask kerko sync index

Features:

• Add many new configuration parameters. Please refer to the configuration parameters documentation for the full list.
• Add optional "Open in Zotero" and "View on zotero.org" buttons to item pages. These are disabled by default (see new parameters kerko.features.open_in_zotero_app and kerko.features.open_in_zotero_web). Even when these are enabled, a user who wishes to use such button must first enable it from the (also new) Preferences dialog.
• Add a web API endpoint for retrieving information about the last synchronization from Zotero.
• Add the kerko config command to the Flask command line interface for displaying all configuration parameters.

Other changes:

• Restructure and expand documentation into a unified documentation site for both Kerko and KerkoApp.
• Add Portuguese translation. Thanks to Gonçalo Cordeiro.

Backwards incompatible changes:

• Raise the minimum required versions of Flask, Flask-Babel, Bootstrap-Flask, and WTForms. If you have a custom application, some of those may introduce breaking changes.
• The data directory has a new default location relative to the instance path. Please check the documentation for the DATA_PATH and INSTANCE_PATH configuration parameters. You may need to set one or both of those parameters, and/or move your existing data directory.
• Almost all configuration parameters have been renamed and/or moved into a hierarchical structure. Hierarchical parameters are referred to using path-like, dot-separated parameter names, and may conveniently be set with the kerko.config_helpers.config_set() function. Here is a mapping of the changed parameters:
  • KERKO_BOOTSTRAP_VERSION → kerko.assets.bootstrap_version
  • KERKO_CSL_STYLE → kerko.zotero.csl_style
  • KERKO_COMPOSER → kerko_composer
  • KERKO_DATA_DIR → DATA_PATH. Now optional, relative to the instance path, and defaulting to kerko instead of data/kerko.
  • KERKO_DOWNLOAD_ATTACHMENT_NEW_WINDOW → kerko.features.download_attachment_new_window
  • KERKO_DOWNLOAD_CITATIONS_LINK → kerko.features.download_citations_link
  • KERKO_DOWNLOAD_CITATIONS_MAX_COUNT → kerko.features.download_citations_max_count
  • KERKO_FEEDS → kerko.feeds.formats
  • KERKO_FEEDS_FIELDS → kerko.feeds.fields
  • KERKO_FEEDS_MAX_DAYS → kerko.feeds.max_days
  • KERKO_FEEDS_REJECT_ANY → kerko.feeds.reject_any
  • KERKO_FEEDS_REQUIRE_ANY → kerko.feeds.require_any
  • KERKO_FULLTEXT_SEARCH → kerko.search.fulltext
  • KERKO_HIGHWIREPRESS_TAGS → kerko.meta.highwirepress_tags
  • KERKO_JQUERY_VERSION → kerko.assets.jquery_version
  • KERKO_PAGE_LEN → kerko.pagination.page_len
  • KERKO_PAGER_LINKS → kerko.pagination.pager_links
  • KERKO_POPPER_VERSION → kerko.assets.popper_version
  • KERKO_PRINT_CITATIONS_LINK → kerko.features.print_citations_link
  • KERKO_PRINT_CITATIONS_MAX_COUNT → kerko.features.print_citations_max_count
  • KERKO_PRINT_ITEM_LINK → kerko.features.print_item_link
  • KERKO_RELATIONS_INITIAL_LIMIT → kerko.features.relations_initial_limit
  • KERKO_RELATIONS_LINKS → kerko.features.relations_links
  • KERKO_RELATIONS_SORT → kerko.features.relations_sort
  • KERKO_RESULTS_ABSTRACTS_MAX_LENGTH → kerko.features.results_abstracts_max_length
  • KERKO_RESULTS_ABSTRACTS_MAX_LENGTH_LEEWAY → kerko.features.results_abstracts_max_length_leeway
  • KERKO_RESULTS_ABSTRACTS → kerko.features.results_abstracts
  • KERKO_RESULTS_ABSTRACTS_TOGGLER → kerko.features.results_abstracts_toggler
  • KERKO_RESULTS_ATTACHMENT_LINKS → kerko.features.results_attachment_links
  • KERKO_RESULTS_FIELDS → kerko.search.result_fields
  • KERKO_RESULTS_URL_LINKS → kerko.features.results_url_links
  • KERKO_TEMPLATE_ATOM_FEED → kerko.templates.atom_feed
  • KERKO_TEMPLATE_BASE → kerko.templates.base
  • KERKO_TEMPLATE_ITEM → kerko.templates.item
  • KERKO_TEMPLATE_LAYOUT → kerko.templates.layout
  • KERKO_TEMPLATE_SEARCH → kerko.templates.search
  • KERKO_TEMPLATE_SEARCH_ITEM → kerko.templates.search_item
  • KERKO_TITLE → kerko.meta.title
  • KERKO_WHOOSH_LANGUAGE → kerko.search.whoosh_language
  • KERKO_WITH_JQUERY → kerko.assets.with_jquery
  • KERKO_WITH_POPPER → kerko.assets.with_popper
  • KERKO_ZOTERO_API_KEY → ZOTERO_API_KEY
  • KERKO_ZOTERO_BATCH_SIZE → kerko.zotero.batch_size
  • KERKO_ZOTERO_LIBRARY_ID → ZOTERO_LIBRARY_ID
  • KERKO_ZOTERO_LIBRARY_TYPE → ZOTERO_LIBRARY_TYPE
  • KERKO_ZOTERO_LOCALE → kerko.zotero.locale
  • KERKO_ZOTERO_MAX_ATTEMPTS → kerko.zotero.max_attempts
  • KERKO_ZOTERO_WAIT → kerko.zotero.wait
• The Kerko configuration should now be initialized by a call like kerko.config_helpers.config_update(app.config, kerko.DEFAULTS).
• Composer.__init__() now only takes a configuration object as argument instead of a bunch of arguments. Thus, the initial values of the Composer instance now depend solely on the configuration.
• Remove the KERKO_USE_TRANSLATIONS configuration variable. Kerko now relies on the application's default Babel domain and translation directories. Custom applications that wish to load Kerko's translations should now add kerko.TRANSLATION_DOMAIN and kerko.TRANSLATION_DIRECTORIES to their Babel configuration.
• The __init__() method of FacetSpec and its subclasses now only accept keyword arguments.
• The sort_key argument to FacetSpec.__init__() is now sort_by.
• Composer built-in fields z_dateAdded and z_dateModified are now named date_added and date_modified respectively.

0.9 (2022-12-29)

Warning: Upgrading from version 0.8.x or earlier will require that you rebuild your search index. Use the following commands, then restart the application:

flask kerko clean index
flask kerko sync index

Features:

• Add expand/collapse actions on facet values, allowing full exploration of hierarchical facets without changing the current search.
• Add an optional initial limit on the number of values to show under each facet. When the initial limit is reached, a "show more" button allows the user to expand the full list.
• Add Atom syndication feeds.
• Allow searching items by their Zotero key.
• Add XML sitemap.
• Add the kerko count CLI command (mostly meant for development purposes).

Bug fixes:

• Fix last sync time not displayed at the bottom of search results when KERKO_PRINT_CITATIONS_LINK and KERKO_DOWNLOAD_CITATIONS_LINK are both set to False.
• Fix the kerko sync CLI command not returning an error code with some types of failures.
• Fix invalid HTML in help modal.

Other changes:

• Handle new Zotero fields introduced with the new 'preprint' item type.
• Apply a boost factor to DOI, ISBN and ISSN fields extracted from the Extra field (previously, only the dedicated Zotero fields had a boost factor).
• Under each facet, always show the facet's active filters first.
• Make facet values with long labels easier to read (by indenting wrapped lines to the right of the checkbox).
• Add link to full bibliography from item pages.
• Add blocks in templates to facilitate theming.
• Remove page parameter from pagination links when page=1.
• Improve documentation.
• Make sync and schema-related error messages more helpful and user-friendly.
• Move pydocstyle config to pyproject.toml.
• Tag package as compatible with Python 3.10 and 3.11.
• Remove leftover code related to Python versions older than 3.7

Backwards incompatible changes:

• Remove the KERKO_FACET_COLLAPSING option. The new initial limit on facets values made this feature largely redundant.
• Remove the collapsible param from the FacetSpec class.
• Remove support for configuration variables KERKO_ZOTERO_START and KERKO_ZOTERO_END (were only used for development and no longer practical).

Changes that might break custom themes:

• The HTML markup and CSS styles of expand/collapse buttons have changed.
• The parameters of the facet, facet_item, facet_items, facet_fields template macros have changed.
• The facets-container, facets, and facets-modal-body element ids are now required in search.html.jinja2.

Possibly backwards incompatible changes (more or less internal API changes):

• Rewrote the criteria module. Criteria.keywords and Criteria.filters work pretty much as before, but everything else has changed.
• Rewrote the query module, which had organically grown into an tangled mess, now replaced with the searcher module. This new API is completely different.
• Adapted view code to the above-mentioned searcher API.
• Split the monolithic views module into multiple modules under views (item_creators, item_facets, item_relations, routes, search), and moved breadbox, meta (as item_meta), pager, and sorter under views.

0.8.1 (2021-11-16)

Bug fixes:

• Fix missing dependency for package building.

0.8 (2021-11-16)

Warning: Upgrading from version 0.7.x or earlier will require that you clean and re-sync your existing search index. Use the following commands, then restart the application:

flask kerko clean index
flask kerko sync

Features:

• Allow full-text search of PDF attachments. This can be disabled by setting KERKO_FULLTEXT_SEARCH to False. Since this feature relies on Zotero's full-text indexing, you must make sure that it works in Zotero first; see Zotero's documentation.
• Add new search scopes "Everywhere" (to search both metadata fields and the text content of attached documents) and "In documents" (to search the text content of attached documents). The scope "In all fields" allows to search all metadata fields, but not the text content of attached documents.
• Display "View on {hostname}" links under search result items, for quick access to the items' URLs. These can be disabled by setting KERKO_RESULTS_URL_LINKS to False.
• Move the "Read" buttons under search result items, as "Read document" links. These can now be disabled by setting KERKO_RESULTS_ATTACHMENT_LINKS to False.
• Display DOI field values as hyperlinks (both in DOI fields, and in the Extra field when lines are prefixed with 'DOI:').
• Add support for imported file attachments, e.g., PDF files imported in your Zotero library through the Zotero Connector. Previously, only "attached copies of files" were supported.
• Standalone notes and file attachments are now allowed into the search index. Kerko filters them out of search results, but custom applications could search them. A new view, standalone_attachment_download, lets one retrieve a standalone file attachment.
• Add configuration options for truncating long abstracts in search results (KERKO_RESULTS_ABSTRACTS_MAX_LENGTH and KERKO_RESULTS_ABSTRACTS_MAX_LENGTH_LEEWAY).
• Embed Highwire Press tags in item pages. This is enabled by default but can be disabled by setting KERKO_HIGHWIREPRESS_TAGS to False.
• Allow tracking with Google Analytics (optional).
• Allow relations in child notes to be specified as HTML links, i.e., in the href attribute of <a> elements.
• Allow inclusion or exclusion of items based on multiple tags (previously, only a single pattern could be checked).

Bug fixes:

• Fix irrelevant sync warnings, from extractors running on attachment items.
• Fix empty prev/next links in search pages metadata.

Other changes:

• Make synchronization from Zotero much more efficient through incremental updates. Instead of performing a full synchronization each time, Kerko now retrieves just the newly added or updated items. This dramatically reduces the number of Zotero API calls (and time) required to update Kerko's search index. Note: More work is planned to eliminate some Zotero API calls that Kerko still makes early in the synchronization process and that could be avoided when its cache is already up-to-date.
• Add a sync cache command to the command line interface.
• On narrow screens, stack search form controls for better usability.
• Respond with an HTTP 503 (Service Unavailable) when the search index is empty or unreadable.
• Make sorts more efficient by setting the sortable Whoosh flag on relevant fields.
• Leading and trailing underscore characters (_) are now trimmed from facet value labels. This happens after sorting the values, which means that the underscore can still be used as a prefix to alter the alphabetical order.
• Support more timezone names. Timezone names such as 'US/Eastern' or 'Europe/London' previously did not work, and times could not be converted to daylight saving times.
• Change labels:
  • "Print this citation" → "Print this record" (on item pages)
  • "Download this citation" → "Download this record" (on item & search pages)
• Inject blocks in item Jinja2 template to facilitate theming.
• Slightly increase some top/bottom margins.
• Add the type HTML attribute to record download links.
• Add the rel="alternate" HTML attribute to record download links on item pages. Also add a corresponding link element to the page head.
• Added utilities for running automated integration tests. This will allow testing many areas of Kerko that previously could hardly be tested.

Backwards incompatible changes:

• Remove deprecated kerko index CLI command (use kerko sync instead).

Possibly backwards incompatible changes (more or less internal API changes):

• Upgrade many dependencies, including new major versions of Flask (2.x), Jinja2 (3.x), Werkzeug (2.x), Click (8.x).
• The default list for the KERKO_RESULTS_FIELDS setting now includes the 'url' field. If you have overridden that setting in your application and KERKO_RESULTS_URL_LINKS is enabled, you'll probably have to add 'url' too.
• The schema field item_type has been renamed to item_type_label. If you have custom templates, please review any use of item.item_type.
• The structure of the kerko/_search-result.html.jinja2 template has changed somewhat. If you have overridden it, you'll need to review the changes.
• The ItemContext class has been eliminated. The Extractor.extract() method now receives an item's dictionary instead of an ItemContext object, and if an item has children these are now available directly in the item (with the children key). If you have created custom extractor classes, their extract() method will need to be adapted accordingly.
• Some extractor classes have been renamed:
  • BaseAttachmentsExtractor → BaseChildAttachmentsExtractor
  • BaseNotesExtractor → BaseChildNotesExtractor
  • LinkedURIAttachmentsExtractor → ChildLinkedURIAttachmentsExtractor
  • NotesTextExtractor → ChildNotesTextExtractor
  • RawNotesExtractor → RawChildNotesExtractor
  • RelationsInNotesExtractor → RelationsInChildNotesExtractor
  • StoredFileAttachmentsExtractor → ChildFileAttachmentsExtractor
• A view has been renamed:
  • item_attachment_download → child_attachment_download
• A default field has been renamed:
  • alternateId → alternate_id

0.7.1 (2021-02-04)

Security fixes:

• Fix unescaped date fields, causing a vulnerability to XSS attacks. This vulnerability was introduced in version 0.7.

Bug fixes:

• Fix wrong locale separator in the HTML lang attribute.

Other changes:

• Remove unwanted spacing after dropdown labels.

Documentation changes:

• Fix missing info about library groupID in configuration docs. Thanks @drmikeuk for reporting the issue.

0.7 (2021-01-08)

Warning: Upgrading from version 0.6 or earlier will require that you clean and re-sync your existing search index. Use the following commands, then restart the application:

flask kerko clean index
flask kerko sync

Features:

• Allow users to toggle the display of abstracts on search results pages.
• Allow inclusion or exclusion of items based on their tags (#4).
• Show attached links to URIs on item pages.
• Show relations on item pages. The relation types provided by default are:
  • Related, based on Zotero's Related field.
  • Cites, managed through child notes containing Zotero URIs and tagged with the _cites tag.
  • Cited by, automatically inferred from Cites relations.
• The Extra field is now searched when searching "in any fields".
• Items that have a DOI, ISBN or ISSN identifier can be referenced by appending their identifier to your Kerko site's base URL.
• Requests for the older URL of an item whose ID has changed are now automatically redirected to the item's current URL. This relies on the dc.replaces relation that's managed internally by Zotero on some operations such as item merges.
• Help users who might mistakenly bookmark a search result's URL rather than the item's permanent URL: Add an id parameter to the search result URLs, and redirect the user to that item's permanent URL if the search result no longer matches because of database changes.
• Redirect to the parent item's page when the user tries to request an attachment that no longer exists.
• Improve accessibility based on WCAG recommendations and WAI-ARIA standards:
  • Add labels to search form elements.
  • Add landmark role search to the search form.
  • Make the purpose of various links more obvious through improved or added labels.
  • Add the aria-label attribute to many elements.
  • Add text to indicate the current value of widgets.
  • Add the aria-current attribute to indicate the current value of widgets.
  • Remove useless link to the current page from the pagination widget.

Bug fixes:

• Fix crash when trying to sync a link attachment (#3).
• Fix unhandled exception during sync when an attachment cannot be downloaded.
• Fix page numbers greater than the page count in search URLs generating wrong page numbers for search result item URLs.
• Fix secondary keys getting sorted in reverse order with some sort options, e.g., when sorting by newest first, results having the same date were then sorted by creator name in reverse alphabetical order instead of alphabetical order.
• Fix empty HTML element taking up horizontal space when there are no badges.

Other changes:

• Display ISO 8601 calendar dates in a more readable format, using the formatting style of the locale.
• Show a timezone abbreviation along with time of last update from Zotero.
• Add German translation. Thanks to @mmoole.
• Fix broken "Getting started" example in README.
• Migrate most package distribution options and metadata from setup.py to setup.cfg.
• Migrate project to a src layout.
• Use Flask-Babel instead of its fork Flask-BabelEx, now that is has merged the translation domain features from Flask-BabelEx.

Backwards incompatible changes:

• Drop support for Python 3.6. Kerko is no longer being tested under Python 3.6. Known issue with 3.6 at this point: some ISO 8601 dates cannot be parsed and reformatted; instead of being displayed in a locale-sensitive manner, these get displayed as is. More issues might arise in the future with Python 3.6 as Kerko continues to evolve.
• All values of the pager dict passed to the _pager.html.jinja2 template are now lists. Previously, only the values at keys 'before' and 'after' were lists; now the values at keys 'previous', 'first', 'current', 'last', and 'next' are lists as well.
• The words 'blacklist' and 'whitelist' in variable names are replaced with 'exclude' and 'include'.
• The KERKO_RESULTS_ABSTRACT configuration variable is replaced by two variables, KERKO_RESULTS_ABSTRACTS (note the now plural form) and KERKO_RESULTS_ABSTRACTS_TOGGLER.
• Citation download URLs now have the form {url_prefix}/{itemID}/export/{format} for individual items ('export' has been inserted), and {url_prefix}/export/{format}/ for search result pages ('download' has been replaced by 'export').
• The Extractor class' interface has changed, improving consistency and separation of concerns:
  • All arguments to __init__() must now be specified as keyword arguments.
  • The extract() method no longer have a document argument, and the spec argument is now the last one. The method now returns a value instead of assigning it to the document.
  • The new extract_and_store() method handles extraction, encoding, and assignment to the document, assigning the value only when it is not None.
• The AttachmentsExtractor class has been renamed to StoredFileAttachmentsExtractor.
• InCollectionExtractor now extends collection membership to subcollections. To preserve the previous behavior, set the check_subcollections parameter to False when initializing the extractor.

Possibly backwards incompatible changes (more or less internal API changes):

• The search_results variable passed to the search.html.jinja2 template is now an iterator of tuples, where the first element of each tuple is a result, and the second element the URL of the result.

0.6 (2020-06-15)

Security fixes:

• Fix multiple vulnerabilities to XSS attacks. All previous versions of Kerko were vulnerable, thus an upgrade is highly recommended.

Backwards incompatible changes:

• Remove default value for the KERKO_DATA_DIR configuration variable. KerkoApp users don't need to worry about this as KerkoApp takes care of it, but custom apps that did not already set this variable now have to.

Features:

• Open PDF documents in the browser's built-in PDF viewer (instead of opening the browser's file download popup).
• Add buttons for opening documents directly from search result pages (these replace the previous paperclip badges).
• Add button at the top of item pages for opening documents (makes the availability of such documents much more obvious).
• Add the KERKO_DOWNLOAD_ATTACHMENT_NEW_WINDOW configuration variable to control whether to open documents in a new window or in the same window.
• Display the date and time of the last successful synchronization from Zotero at the bottom of search results.

Bug fixes:

• Preserve newlines when displaying the value of the Extra field.
• Preserve newlines when displaying abstracts in search result pages.
• Fix filters missing on search pages that have no results.
• Avoid empty box in print media when there is no search criteria.
• Avoid empty box when the search index is missing.
• Fix pluralization in CLI time elapsed messages.

Other changes:

• Refer to attachments as "documents" in the interface, and replace the paperclip icon with a file icon.
• Remove CSRF token from search form. Token expiration can impede legitimate users, and the token is unnecessary as the form does not change the application's state.
• Add a proper message when none of the filters provided in the URL are recognized.
• Improve documentation.
• Add INFO-level log message to report successful synchronization from Zotero.
• Add blocks in templates to facilitate theming.

Possibly backwards incompatible changes (more or less internal API changes):

• Rename the content_with_badges template macro as badges, and leave it to the caller to display content.
• Remove badges that are related to attachments.

0.5 (2019-11-19)

Warning: Upgrading from version 0.4 or earlier will require that you clean and re-sync your existing search index. Use the following commands:

flask kerko clean index
flask kerko sync

Features:

• Add support for Zotero attachments.
• Allow configuration of badges on items. The 'attachment' badge is provided by default, displaying an icon on items that have one or more attachments.
• Add help modal.
• Improve customizability:
  • Add KERKO_TEMPLATE_* configuration variables for page template names.
  • Use configurable, separate templates to render facets and badges (see the renderer argument to kerko.specs.FacetSpec, kerko.specs.BadgeSpec).
  • Add the KERKO_RESULTS_FIELDS configuration variable to specify which fields to retrieve with search queries.
• Add building blocks for creating boolean facets based on collection membership (new class kerko.extractors.InCollectionExtractor, new parameters for kerko.codecs.BooleanFacetCodec).

Bug fixes:

• Fix facets not ordered by weight on item page.
• Preserve newlines in abstract display.
• Fix incorrect use of bookmark link on item pages, set canonical link instead.
• Prevent text overflow in some browsers on citations containing long URLs.

Other changes:

• Deprecate CLI command kerko index in favor of new command kerko sync.
• Change title of the "Refine" panel to "Explore".
• Change labels of the "Print" and "Download" buttons to "Print this citation" and "Download this citation", to prevent any confusion with attachment downloading.
• Show the facets in a more robust and accessible Bootstrap modal, on small screens, instead of the home-built drawer.
• Use compact pagination widget on small screens.
• Tweak sizing, positioning, and spacing of various UI elements.
• Improve accessibility of various UI elements.
• Make citation stand out more in item page.
• Hide some elements and decorations in print media.
• Make search query more efficient on item page.

Possibly backwards incompatible changes (more or less internal API changes):

• Force keyword arguments with kerko.composer.Composer.__init__().
• Rename kerko.composer.Composer.__init__() arguments default_note_whitelist_re as default_child_whitelist_re, default_note_blacklist_re as default_child_blacklist_re.
• Rename method kerko.views.item() as kerko.views.item_view().
• Rename template file _facet.html.jinja2 as _facets.html.jinja2.
• Replace argument checkboxes in template macro field() with add_link_icon and remove_link_icon.

0.4 (2019-09-28)

Features:

• Allow search term boosting in relevance score calculation, e.g. faceted^2 search browsing^0.5.

Security fixes:

• Update minimum Werkzeug version to 0.15.3. See CVE-2019-14806: "Pallets Werkzeug before 0.15.3, when used with Docker, has insufficient debugger PIN randomness because Docker containers share the same machine id."

Other changes:

• Update jQuery version to 3.4.1.
• Update French translations (translate boolean search operators).
• Improve search form validation and error display.
• Disable not-so-intuitive boolean search operators (AndNot, AndMaybe, Require were unwanted but enabled by default by Whoosh's OperatorsPlugin).
• Improve documentation.
• Code cleanup.

0.3 (2019-07-29)

Features:

• Exporting: users may export individual citations as well as complete bibliographies corresponding to search results. By default, download links are provided for the RIS and BibTeX formats, but applications may be configured to export any format supported by the Zotero API.

Bug fixes:

• Fix bad alignment of field names in print mode.
• Remove warning when indexing an item with no authors (#1).

Other changes:

• Move print button to bottom of search pages (next to the new download dropdown).
• Improve documentation.
• Compile message catalog before building sdist and wheel.

Possibly backwards incompatible changes (more or less internal API changes):

• Method kerko.composer.Composer.get_ordered_specs() replaces get_ordered_scopes(), get_ordered_facets() and get_ordered_sorts().

0.3alpha1 (2019-07-17)

• Fix broken links in documentation.

0.3alpha0 (2019-07-16)

• First PyPI release.