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WikibaseMediaInfo is an extension to 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](#MediaInfo Entity (M-item)). The user can view, create, edit, and delete this data.

Requirements

System-level dependencies

  • ElasticSearch* (see here for more information on how to install)
  • Node.js v6 for testing during development. Node dependency will be upgraded to a more recent LTS version once our CI system can support it.

MW Extensions

The following MediaWiki extensions must be installed and configured prior to installing WikibaseMediaInfo:

Search Features

WikibaseMediaInfo adds some new search features. To use them, you need to install and configure the following search-related extensions:

UploadWizard Features

WikibaseMediaInfo also adds new functionality to the UploadWizard Extension, but it is not required.

Installation

After CirrusSearch and Wikibase are set up properly, enable the extension by adding wfLoadExtension( 'WikibaseMediaInfo' ); along with the required config variables to LocalSettings.php.

You might need to run composer install in the extension directory, or in the root directory of your MediaWiki installation if you are using a setup that merges all extension's dependencies into MediaWiki's vendor directory.

Post-install setup

Depicts Property

A basic building-block of Wikibase is the Statement. The claim made by a given statement has two basic parts, properties and values. Currently WikibaseMediaInfo supports statements that feature a single property: the Depicts property.

If you are running this extension in a local development environment, you will need to add a Wikibase record for this property. The easiest way to do that is:

  1. Navigate to Special:NewProperty
  2. Add an item with label set to depicts. Make sure to set the data type to item.
  3. Update your LocalSettings.php file so that the depicts property is set to the ID of the property you just created:
$wgMediaInfoProperties = [
	'depicts' => 'P123',
];

Entities

In order to add values to statements, you will also need to add Entity items to your local Wikibase instance. This can be done manually at: Special:NewItem, or through using the WikibaseImport script (see below).

WikibaseImport

You can optionally use the unofficial WikibaseImport extension to automate the process of importing entities from another Wikibase instance (such as Wikidata). See that project's README for more information.

Federation

TBD

Less variables

Since Wikimedia UI base variables aren't in core, we require them as a package dependency, then use a shell script to copy them to the lib directory. To update the base variables, require the new version in package.json and install it, then run npm run build-lib to copy the updated file into lib. Commit the updated files.

We're including the base variables in our custom variables file, resources/mediainfo-variables.less. To use them in other files, include mediainfo-variables.less rather than directly including the base file itself.

Configuration

Extension configuration variables are sets of key-value pairs. They are documented in more detail in WikibaseMediaInfo/extension.json. Config variables should be added toLocalSettings.php. The following config options are available for this extension:

variable example value default notes
$wgMediaInfoProperties [ 'depicts' => 'P123' ] {} default WB properties to show (e.g. "depicts")
$wgMediaInfoHelpUrls [ 'P1' => 'https://commons.wikimedia.org/wiki/Special:MyLanguage/Commons:Depicts' ] {} Links to pages to learn more about wikibase properties
$wgUploadWizardConfig[ 'wikibase' ][ 'enabled' ] true/false false UploadWizard feature-flag
$wgUploadWizardConfig[ 'wikibase' ][ 'captions' ] true/false false UploadWizard feature-flag
$wgUploadWizardConfig[ 'wikibase' ][ 'statements' ] true/false false UploadWizard feature-flag

MediaInfo Glossary

Property (P-item)

A property is used to categorize or describe a file. It has a unique id in wikibase in the form Pxxx such as P123. Examples of file properties are 'depicts' (what an image is a picture of), 'resolution', 'created by', 'license'.

Item (Q-item)

An item is the concept, topic, or object. It is represented by a unique id in the form Qxxx. For example on Wikidata the planet Earth is the item Q2 and the CC0 licence is Q6938433.

Claim

A single fact about a media file consisting of a key-value pair (usually a property-item) such as Licence=CC-By-SA or Depicts=Dog. Claims are stored simply as strings, using the property ids and item ids as appropriate. For example, an image depicting a black cat could have the claim depicts=cat(color=black).

Captions

A short piece of text describing a media file, plus its language. This is used to WikibaseMediaInfo to provide a short description of the file (the same as 'labels' in wikibase).

MediaInfo Entity (M-item)

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
  • any number of claims

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

Qualifiers

A qualifier is a secondary claim that modifies the primary claim. 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)'.

MediaInfo UI

MediaInfo entities are shown on, and can be edited from, their associated File page. Captions and claims are shown separately, and claims are split into 'depicts' claims and 'other' claims.

Search

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 a single claim

Assume ['depicts': 'P1] is the media info property

To search for a claim, use the haswbstatement keyword. For example, to search for images with Mont Blanc (Q583) search for haswbstatement:P1=Q583.

Searches for claims can also use qualifiers. For example, to search for images with Mont Blanc (Q583) in the background (Q13217555), where P518 is the property ‘applies to part’ use:

haswbstatement:P1=Q583[P518=Q13217555]

Searching across multiple claims at once

Claims can be combined using a logical OR in a single search keyword using the pipe character |. For example files depicting a cat (Q146) OR a dog (Q144) can be found using

haswbstatement:P1=Q146|P1=Q144

Claims can be combined using a logical AND by using 2 separate search keywords. For example, files depicting a cat AND a dog can be found using:

haswbstatement:P1=Q146 haswbstatement:P1=Q144

Searching for claims with quantity qualifiers

To search for a claim with a quantity, use the wbstatementquantity keyword. For example, files that depict 2 humans (Q5) can be found using:

wbstatementquantity:P1=Q5=2

The comparison operators >, >=, < and <= can also be used, so a search for files depicting more than 2 humans can be found using:

wbstatementquantity:P1=Q5>2

Searching for a range of values

Ranges can be searched for using two wbstatementquantity keywords at once. For example, to find files depicting between 2 and 5 humans (Q5) use:

wbstatementquantity:P1=Q5>=2 wbstatementquantity:P1=Q5<=5

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 opening_text field

  • Claims are stored in the format propertyID=value as array elements in the statement_keywords field using the wikibase property ID (and item id, if value is an item)

    e.g. ‘depicts house cat’ is stored as P1=Q146

  • Claims with qualifiers are stored in the statement_keywords field along with their qualifiers in the format propertyID=value[qualifierPropertyID=qualifierValue].

    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 P1=Q12418[P518=Q13217555]

    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 P1=Q12418 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 statement_quantity field in the format propertyID=value|quantity, eg. ‘depicts human, quantity 1’ is stored as P1=Q5|1.

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 ‘some 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 ($wgWBRepoSettings['searchIndexPropertiesExclude']) AND
  • either
    • its property ID is in a configurable list of property IDs that should be indexed ($wgWBRepoSettings['searchIndexProperties']) OR
    • its property type is in a configurable list of property types that should be indexed ($wgWBRepoSettings['searchIndexTypes'])

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 ($wgWBRepoSettings['searchIndexQualifierPropertiesForQuantity']).

Tests

PHPUnit

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

Tests relying on the MediaWiki framework (located in tests/phpunit/mediawiki) must by run using MediaWiki core's composer phpunit:entrypoint command.

Node-QUnit

This extension supports headless testing of JS components using Node.js and QUnit. These tests are defined in tests/node-qunit. To run them, open a terminal and run npm run test:unit. They are also included in the larger npm test script (which means they will run in CI).

Node version 6.x should be used if you are running tests locally, for closer parity with CI and production.

Test Dependencies

package.json defines a number of devDependencies which are used in the testing environment, including some front-end modules which are declared and loaded via PHP at runtime (OOJS, OOUI, jQuery etc). These dependencies will need to be updated here manually if the package versions in core's maintenance/resources/foreign-resources.yaml file change. Versions should be pinned exactly to avoid any potential problems.

See also