WP_Plugin_Dependencies

Last updated: March 4, 2026

Static class for resolving plugin dependencies declared via the Requires Plugins header.

Source: wp-includes/class-wp-plugin-dependencies.php
Since: 6.5.0

Overview

All methods are static. The class maintains internal state via static properties and must be initialized before use.

Properties

Property	Type	Visibility	Description
`$plugins`	array	protected static	Cached result of `get_plugins()`
`$plugin_dirnames`	array	protected static	Map of slug → plugin filepath
`$dependencies`	array	protected static	Map of plugin filepath → dependency slugs
`$dependency_slugs`	array	protected static	All unique dependency slugs
`$dependent_slugs`	array	protected static	Map of plugin filepath → dependent slug
`$dependency_api_data`	array	protected static	WordPress.org API data for dependencies
`$dependency_filepaths`	string[]	protected static	Map of dependency slug → installed filepath
`$circular_dependencies_pairs`	array[]	protected static	Circular dependency pairings
`$circular_dependencies_slugs`	string[]	protected static	Slugs involved in circular deps
`$initialized`	bool	protected static	Whether class has been initialized

Public Methods

initialize()

Initializes dependency data by reading plugin headers and fetching API data.

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public static function initialize(): void

Note: Only runs once; subsequent calls are no-ops.

has_dependents()

Checks if other plugins depend on this plugin.

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public static function has_dependents( string $plugin_file ): bool

Parameter	Type	Description
`$plugin_file`	string	Plugin filepath relative to plugins directory

Returns: true if other plugins list this as a dependency.

has_dependencies()

Checks if this plugin requires other plugins.

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public static function has_dependencies( string $plugin_file ): bool

Parameter	Type	Description
`$plugin_file`	string	Plugin filepath relative to plugins directory

Returns: true if plugin has a Requires Plugins header.

has_active_dependents()

Checks if any active plugins depend on this plugin.

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public static function has_active_dependents( string $plugin_file ): bool

Parameter	Type	Description
`$plugin_file`	string	Plugin filepath relative to plugins directory

Returns: true if at least one active plugin requires this one.

Use Case: Prevent deactivation of plugins that active plugins depend on.

get_dependents()

Gets filepaths of plugins that require a dependency.

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public static function get_dependents( string $slug ): array

Parameter	Type	Description
`$slug`	string	Dependency plugin slug

Returns: Array of dependent plugin filepaths.

get_dependencies()

Gets dependency slugs for a plugin.

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public static function get_dependencies( string $plugin_file ): array

Parameter	Type	Description
`$plugin_file`	string	Plugin filepath relative to plugins directory

Returns: Array of dependency slugs, or empty array if none.

get_dependent_filepath()

Gets the filepath for a dependent plugin by its slug.

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public static function get_dependent_filepath( string $slug ): string|false

Parameter	Type	Description
`$slug`	string	Dependent plugin slug

Returns: Plugin filepath, or false if not found.

has_unmet_dependencies()

Checks if any required plugins are missing or inactive.

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public static function has_unmet_dependencies( string $plugin_file ): bool

Parameter	Type	Description
`$plugin_file`	string	Plugin filepath relative to plugins directory

Returns: true if any dependency is not installed or inactive.

has_circular_dependency()

Checks if plugin is involved in a circular dependency.

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public static function has_circular_dependency( string $plugin_file ): bool

Parameter	Type	Description
`$plugin_file`	string	Plugin filepath relative to plugins directory

Returns: true if plugin has circular dependencies (A→B→A).

get_dependent_names()

Gets human-readable names of plugins that require this one.

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public static function get_dependent_names( string $plugin_file ): array

Parameter	Type	Description
`$plugin_file`	string	Plugin filepath relative to plugins directory

Returns: Array of dependent plugin names (sorted alphabetically).

get_dependency_names()

Gets human-readable names of required plugins.

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public static function get_dependency_names( string $plugin_file ): array

Parameter	Type	Description
`$plugin_file`	string	Plugin filepath relative to plugins directory

Returns: Map of dependency slug → name. Falls back to API data, then installed plugin name, then slug.

get_dependency_filepath()

Gets installed filepath for a dependency.

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public static function get_dependency_filepath( string $slug ): string|false

Parameter	Type	Description
`$slug`	string	Dependency plugin slug

Returns: Plugin filepath, or false if not installed.

get_dependency_data()

Gets WordPress.org API data for a dependency.

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public static function get_dependency_data( string $slug ): array|false

Parameter	Type	Description
`$slug`	string	Dependency plugin slug

Returns: API data array (name, short_description, icons, etc.), or false if unavailable.

display_admin_notice_for_unmet_dependencies()

Displays admin warning if dependencies are missing.

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public static function display_admin_notice_for_unmet_dependencies(): void

Output: Warning notice with link to plugins page (respects multisite).

display_admin_notice_for_circular_dependencies()

Displays admin warning for circular dependencies.

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public static function display_admin_notice_for_circular_dependencies(): void

Output: Warning notice listing circular dependency pairs.

check_plugin_dependencies_during_ajax()

AJAX handler for post-installation dependency validation.

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public static function check_plugin_dependencies_during_ajax(): void

AJAX Action: Called after plugin installation.
Nonce: updates
POST Parameter: slug

Response:

Key	Type	Description
`slug`	string	Plugin slug
`pluginName`	string	Plugin name
`plugin`	string	Plugin filepath
`activateUrl`	string	Activation URL (if eligible)
`message`	string	Success message
`errorCode`	string	Error type
`errorMessage`	string	Error description
`errorData`	array	Inactive dependency names

Protected Methods

get_plugins()

Returns cached plugin data.

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protected static function get_plugins(): array

Returns: Result of get_plugins().

read_dependencies_from_plugin_headers()

Parses Requires Plugins headers from all plugins.

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protected static function read_dependencies_from_plugin_headers(): void

Populates: $dependencies, $dependency_slugs, $dependent_slugs

sanitize_dependency_slugs()

Sanitizes comma-separated dependency slugs.

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protected static function sanitize_dependency_slugs( string $slugs ): array

Parameter	Type	Description
`$slugs`	string	Comma-separated slug string

Returns: Array of sanitized slugs.

Validation: Must match WordPress.org slug format (/^[a-z0-9]+(-[a-z0-9]+)*$/).

Filters: Applies wp_plugin_dependencies_slug to each slug.

get_dependency_filepaths()

Builds map of dependency slugs to installed filepaths.

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protected static function get_dependency_filepaths(): array

Returns: Map of slug → filepath (or false if not installed).

get_dependency_api_data()

Fetches plugin data from WordPress.org API.

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protected static function get_dependency_api_data(): array|void

Returns: API data array, or void if not in admin context.

Caching:

Main data: wp_plugin_dependencies_plugin_data transient (no expiry)
Per-slug timeout: wp_plugin_dependencies_plugin_timeout_{$slug} (12 hours)

Context: Only runs on plugins.php or plugin-install.php.

get_plugin_dirnames()

Builds slug → filepath map for all plugins.

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protected static function get_plugin_dirnames(): array

Returns: Map of slug → plugin filepath.

get_circular_dependencies()

Detects all circular dependency pairs.

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protected static function get_circular_dependencies(): array[]

Returns: Array of [slug_a, slug_b] pairs.

check_for_circular_dependencies()

Recursive helper for circular dependency detection.

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protected static function check_for_circular_dependencies( 
    array $dependents, 
    array $dependencies 
): array

Parameter	Type	Description
`$dependents`	array	Chain of dependent slugs being checked
`$dependencies`	array	Dependencies to check against

Returns: Array of circular dependency pairs found.

convert_to_slug()

Converts plugin filepath to slug.

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protected static function convert_to_slug( string $plugin_file ): string

Parameter	Type	Description
`$plugin_file`	string	Plugin filepath

Returns: Plugin slug.

Special Case: hello.php → hello-dolly

Logic:

With directory: my-plugin/my-plugin.php → my-plugin
Single file: my-plugin.php → my-plugin

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