Extension:WikibaseMediaInfo

WikibaseMediaInfo is an extension to 1>Special:MyLanguage/Extension:Wikibase|Wikibase adding a MediaInfo entity for handling structured data about multimedia files.

The extension hooks into the File Page. It stores supplemental metadata (captions and depicts statements) about the file in a MediaInfo Entity. The user can view, create, edit, and delete this data.

Requirements

 * UniversalLanguageSelector
 * CirrusSearch
 * Wikibase (follow instructions for both client and repo)
 * WikibaseCirrusSearch

Installation

 * Ensure CirrusSearch, Wikibase (client and repo) and WikibaseCirrusSearch are set up properly.


 * Add configuration.

MediaInfo UI
MediaInfo entities are shown on, and can be edited from, their associated File page and while uploading a file via UploadWizard.

There are separate sections in the UI for editing captions and statements.

An editing interface for is always shown for default properties (defaults are defined in config). On live commons depicts is the only default property - users are encouraged to say what is depicted by an image. Statements with other properties can be added by the user at will.

MediaInfo Entity
A Wikibase entity that contains structured data about media files. It is stored in a slot on a File page and consists of


 * an ID in the form Mxxx, where xxx is the id of the associated wiki page
 * any number of captions (one per language)
 * any number of statements

(Note: if there is no caption or statement data then the entity is not stored in the database - in this case it is known as a ‘virtual entity’)

Caption
A short piece of text describing a media file, plus its language. Used to provide a short description of the file (the same as ‘labels’ in wikibase).

Statement
A single fact about a media file consisting of a key-value pair such as  or.

Keys are always a property. Values can be any wikibase datatype, but for now only item values are supported by the UI.

Note that normally in wikibase what we are describing as a 'statement' here is known as a 'claim', and that a wikibase 'statement' means a claim PLUS a documentary reference. Because we don't typically have documentary references for descriptions of files, 'statement' and 'claim' are used interchangeably in MediaInfo.

Property
A property is a property of a file that can have a value - for example ‘depicts’ (what an image is a picture of), ‘resolution’, ‘created by’, ‘license’. Each property has a unique id in wikibase in the form  such as.

Item
An item is a concept, topic, or object with an id - for example on Wikidata the CC0 licence is Q6938433, physics is Q413 and the planet Earth is Q2. Each item has a unique id in wikibase in the form  such as.

Qualifier
A qualifier is a secondary statement that modifies the primary statement. For example an image might have a tree in the foreground and the sea in the background, in which case it could have 2 ‘depicts’ claims associated with it - ‘depicts=tree(applies to part=foreground)’ and ‘depicts=sea(applies to part=background)’.

Search by caption
Users can search for files by their MediaInfo captions just as they would search for anything else. For example, if a user uploads a picture of the Eiffel Tower, and enters ‘Tour Eiffel’ (French) and ‘Eiffel Tower’ (English) as multilingual file captions, the picture is findable by another user searching for either ‘Eiffel Tower’ or ‘Tour Eiffel’.

Searching for claims/statements
Searching for claims/statements happens via WikibaseCirrusSearch keywords, for details see:

Search implementation
When the File page is saved, the following MediaInfo data is written to the Elasticsearch index (all examples use Wikidata Property and Item ids):


 * Captions data in every language is stored in the  field


 * Claims are stored in the format  as array elements in the   field using the wikibase property ID (and item id, if value is an item) - e.g. ‘depicts house cat’ is stored as  


 * Claims with qualifiers are stored in the  field along with their qualifiers in the format  .  For example, the Mona Lisa painting (Wikidata item Q12418) depicts a sky (Q13217555) in the background (Wikidata property P518). If we arrange this data in a Wikibase claim, it would be: ‘depicts sky, applies to part background’, which would be stored as  


 * Note that claims with qualifiers are also stored without the qualifier, to increase their findability. So, for example, if someone entered the above claim-plus-qualifier, the claim   is also stored, so that someone can find the file by searching for ‘depicts sky’ alone, as well as by searching for ‘depicts sky, applies to part background’.


 * Claims data with qualifiers where the qualifier value is a quantity is stored in the  field in the format , eg. ‘depicts human, quantity 1’ is stored as  .

Note that not all claims are stored. A claim will be indexed in ElasticSearch only if ALL of the following conditions are true:


 * The claim has a real value (i.e. its value is not ‘no value’ or ‘unknown value’) AND


 * We know how to process its value for indexing. More value processors may be added in future, but currently we require the claim’s value to be either a Q item ID, a string (alphanumeric), or a quantity (numeric) AND


 * the claims’s Wikidata property ID is NOT in a configurable list of excluded IDs AND either its property ID is in a configurable list of property IDs that should be indexed  ORits property type is in a configurable list of property types that should be indexed

Note that for a claim’s quantities to be stored, the claim must meet all the criteria above AND the property ID for the quantity qualifier must be present in a configurable list of property IDs.

Configuration
Extension configuration variables are sets of key-value pairs. They are documented in more detail in. All config variables are added to.

The following config options are available for this extension:

Config (in LocalSettings.php)

 *   Default wikibase properties that will always be shown, allowing users to add/edit/delete values for them, on the File page/UploadWizard, regardless or not they already have a value. On live commons this is the 'depicts' property, as we want to encourage users to fill in values for this in particular. Value is an array of key-value pairs connecting a label name to an existing wikibase database id.


 *   Urls for pages where a user can learn more about particular wikibase properties - if there is a help url for a particular property then there will be a "learn more" link for that property that leads to the url from the config.


 *   Set to true to allow users to add statements with properties that are not specified in  via the UI on File page/UploadWizard. ATM only properties whose values are wikibase items are supported, properties with data-type 'string', 'geo-coordinate', 'quantity' etc will be supported at some stage in the future.


 *   If  is false then properties for qualifiers for statements are limited to those properties defined in this variable. Value is an array of key-value pairs connecting a label name to an existing wikibase database id. If   is true then this config variable is ignored.

Other Config

 *   Enables MediaInfo data on UploadWizard when set to true.

Tests
PHPUnit tests are located in. You can run tests not requiring the MediaWiki framework (located in ) by running. This command also runs code style checks using PHPCS.

Tests relying on the MediaWiki framework (located in ) must by run using MediaWiki core’s   endpoint.

Javascript tests are located in. You can run tests from a terminal with. Node version 6.x should be used.

More information about the testing approaches being used in this extension's development can be found here.