add_query_arg() WordPress Function

The add_query_arg() function is used to add query strings to a URL in WordPress. This function is useful for adding custom variables to a URL, for example, when tracking referrals. Query strings are added to the end of a URL, after a question mark. Each query string consists of a key and a value, separated by an equals sign. Multiple query strings are separated by ampersands. The add_query_arg() function accepts two arguments: the key and the value. The key is the name of the custom variable, and the value is the value of the variable. For example, to add a query string with the key "ref" and the value "123", you would use the following code: add_query_arg( 'ref', '123', 'http://example.com' ); This would add the following query string to the URL: http://example.com/?ref=123 You can also use the add_query_arg() function to add multiple query strings to a URL. For example, the following code would add two query strings to the URL: add_query_arg( array( 'ref' => '123', 'source' => 'newsletter' ), 'http://example.com' ); This would add the following query strings to the URL: http://example.com/?ref=123&source=newsletter

add_query_arg( $args ) #

Retrieves a modified URL query string.

Contents

Description

You can rebuild the URL and append query variables to the URL query by using this function. There are two ways to use this function; either a single key and value, or an associative array.

Using a single key and value:

add_query_arg( 'key', 'value', 'http://example.com' );

Using an associative array:

add_query_arg( array(
    'key1' => 'value1',
    'key2' => 'value2',
), 'http://example.com' );

Omitting the URL from either use results in the current URL being used (the value of $_SERVER['REQUEST_URI']).

Values are expected to be encoded appropriately with urlencode() or rawurlencode().

Setting any query variable’s value to boolean false removes the key (see remove_query_arg()).

Important: The return value of add_query_arg() is not escaped by default. Output should be late-escaped with esc_url() or similar to help prevent vulnerability to cross-site scripting (XSS) attacks.

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Parameters

$key

(string|array)(Required)Either a query variable key, or an associative array of query variables.

$value

(string)(Optional) Either a query variable value, or a URL to act upon.

$url

(string)(Optional) A URL to act upon.

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Return

(string) New URL query string (unescaped).

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More Information

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Usage

// Parameters as separate arguments
add_query_arg( $param1, $param2, $old_query_or_uri );

// Parameters as array of key => value pairs
add_query_arg( 
    array( 
        'key1' => 'value1',
        'key2' => 'value2',
        ...
    ), 
    $old_query_or_uri 
);

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Source

File: wp-includes/functions.php

function add_query_arg( ...$args ) {
	if ( is_array( $args[0] ) ) {
		if ( count( $args ) < 2 || false === $args[1] ) {
			$uri = $_SERVER['REQUEST_URI'];
		} else {
			$uri = $args[1];
		}
	} else {
		if ( count( $args ) < 3 || false === $args[2] ) {
			$uri = $_SERVER['REQUEST_URI'];
		} else {
			$uri = $args[2];
		}
	}

	$frag = strstr( $uri, '#' );
	if ( $frag ) {
		$uri = substr( $uri, 0, -strlen( $frag ) );
	} else {
		$frag = '';
	}

	if ( 0 === stripos( $uri, 'http://' ) ) {
		$protocol = 'http://';
		$uri      = substr( $uri, 7 );
	} elseif ( 0 === stripos( $uri, 'https://' ) ) {
		$protocol = 'https://';
		$uri      = substr( $uri, 8 );
	} else {
		$protocol = '';
	}

	if ( strpos( $uri, '?' ) !== false ) {
		list( $base, $query ) = explode( '?', $uri, 2 );
		$base                .= '?';
	} elseif ( $protocol || strpos( $uri, '=' ) === false ) {
		$base  = $uri . '?';
		$query = '';
	} else {
		$base  = '';
		$query = $uri;
	}

	wp_parse_str( $query, $qs );
	$qs = urlencode_deep( $qs ); // This re-URL-encodes things that were already in the query string.
	if ( is_array( $args[0] ) ) {
		foreach ( $args[0] as $k => $v ) {
			$qs[ $k ] = $v;
		}
	} else {
		$qs[ $args[0] ] = $args[1];
	}

	foreach ( $qs as $k => $v ) {
		if ( false === $v ) {
			unset( $qs[ $k ] );
		}
	}

	$ret = build_query( $qs );
	$ret = trim( $ret, '?' );
	$ret = preg_replace( '#=(&|$)#', '$1', $ret );
	$ret = $protocol . $base . $ret . $frag;
	$ret = rtrim( $ret, '?' );
	$ret = str_replace( '?#', '#', $ret );
	return $ret;
}

Expand full source codeCollapse full source codeView on TracView on GitHub

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Uses

Uses
UsesDescription
wp-includes/class-pop3.php:stripos()
wp-includes/formatting.php:wp_parse_str()

Parses a string into variables to be stored in an array.

wp-includes/formatting.php:urlencode_deep()

Navigates through an array, object, or scalar, and encodes the values to be used in a URL.

wp-includes/functions.php:build_query()

Build URL query based on an associative and, or indexed array.

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Used By

Used By
Used ByDescription
wp-includes/rest-api/endpoints/class-wp-rest-sidebars-controller.php:WP_REST_Sidebars_Controller::prepare_links()

Prepares links for the sidebar.

wp-admin/update-core.php:core_auto_updates_settings()

Display WordPress auto-updates settings.

wp-includes/rest-api/endpoints/class-wp-rest-block-directory-controller.php:WP_REST_Block_Directory_Controller::prepare_links()

Generates a list of links to include in the response for the plugin.

wp-includes/rest-api/endpoints/class-wp-rest-block-types-controller.php:WP_REST_Block_Types_Controller::prepare_links()

Prepares links for the request.

wp-admin/includes/class-plugin-installer-skin.php:Plugin_Installer_Skin::do_overwrite()

Check if the plugin can be overwritten and output the HTML for overwriting a plugin on upload.

wp-admin/includes/class-theme-installer-skin.php:Theme_Installer_Skin::do_overwrite()

Check if the theme can be overwritten and output the HTML for overwriting a theme on upload.

wp-admin/includes/class-wp-ms-themes-list-table.php:WP_MS_Themes_List_Table::column_autoupdates()

Handles the auto-updates column output.

wp-admin/includes/class-wp-privacy-data-removal-requests-list-table.php:WP_Privacy_Data_Removal_Requests_List_Table::column_email()

Actions column.

wp-admin/includes/class-wp-privacy-data-removal-requests-list-table.php:WP_Privacy_Data_Removal_Requests_List_Table::column_next_steps()

Next steps column.

wp-admin/includes/class-wp-ms-sites-list-table.php:WP_MS_Sites_List_Table::get_views()

Gets links to filter sites by status.

wp-admin/includes/class-wp-privacy-data-export-requests-list-table.php:WP_Privacy_Data_Export_Requests_List_Table::column_email()

Actions column.

wp-admin/includes/class-wp-privacy-data-export-requests-list-table.php:WP_Privacy_Data_Export_Requests_List_Table::column_next_steps()

Displays the next steps column.

wp-includes/class-wp-recovery-mode-link-service.php:WP_Recovery_Mode_Link_Service::handle_begin_link()

Enters recovery mode when the user hits wp-login.php with a valid recovery mode link.

wp-includes/class-wp-recovery-mode-link-service.php:WP_Recovery_Mode_Link_Service::get_recovery_mode_begin_url()

Gets a URL to begin recovery mode.

wp-includes/admin-bar.php:wp_admin_bar_recovery_mode_menu()

Adds a link to exit recovery mode when Recovery Mode is active.

wp-admin/includes/theme.php:resume_theme()

Tries to resume a single theme.

wp-admin/includes/update.php:wp_recovery_mode_nag()

Displays a notice when the user is in recovery mode.

wp-admin/includes/class-wp-site-health.php:WP_Site_Health::get_test_rest_availability()

Test if the REST API is accessible.

wp-admin/includes/class-wp-site-health.php:WP_Site_Health::get_test_https_status()

Test if your site is serving content over HTTPS.

wp-admin/includes/plugin.php:resume_plugin()

Tries to resume a single plugin.

wp-admin/includes/misc.php:wp_check_php_version()

Checks if the user needs to update PHP.

wp-includes/rest-api/endpoints/class-wp-rest-search-controller.php:WP_REST_Search_Controller::get_items()

Retrieves a collection of search results.

wp-includes/script-loader.php:wp_get_script_polyfill()

Returns contents of an inline script used in appending polyfill scripts for browsers which fail the provided tests. The provided array is a mapping from a condition to verify feature support to its polyfill script handle.

wp-admin/includes/template.php:do_block_editor_incompatible_meta_box()

Renders a “fake” meta box with an information message, shown on the block editor, when an incompatible meta box is found.

wp-includes/user.php:wp_send_user_request()

Send a confirmation request email to confirm an action.

wp-admin/includes/class-wp-privacy-requests-table.php:WP_Privacy_Requests_Table::get_views()

Get an associative array ( id => link ) with the list of views available on this table.

wp-includes/class-wp-customize-manager.php:WP_Customize_Manager::handle_load_themes_request()

Loads themes into the theme browsing/installation UI.

wp-admin/press-this.php:wp_load_press_this()
wp-admin/includes/misc.php:wp_print_plugin_file_tree()

Outputs the formatted file list for the plugin file editor.

wp-admin/includes/misc.php:wp_print_theme_file_tree()

Outputs the formatted file list for the theme file editor.

wp-admin/includes/file.php:wp_edit_theme_plugin_file()

Attempts to edit a file for a theme or plugin.

wp-includes/class-wp-customize-manager.php:WP_Customize_Manager::add_state_query_params()

Adds customize state query params to a given URL if preview is allowed.

wp-includes/rest-api/endpoints/class-wp-rest-users-controller.php:WP_REST_Users_Controller::get_items()

Retrieves all users.

wp-includes/rest-api/endpoints/class-wp-rest-revisions-controller.php:WP_REST_Revisions_Controller::get_items()

Gets a collection of revisions.

wp-includes/rest-api/endpoints/class-wp-rest-post-statuses-controller.php:WP_REST_Post_Statuses_Controller::prepare_item_for_response()

Prepares a post status object for serialization.

wp-includes/rest-api/endpoints/class-wp-rest-terms-controller.php:WP_REST_Terms_Controller::prepare_links()

Prepares links for the request.

wp-includes/rest-api/endpoints/class-wp-rest-terms-controller.php:WP_REST_Terms_Controller::get_items()

Retrieves terms associated with a taxonomy.

wp-includes/rest-api/endpoints/class-wp-rest-posts-controller.php:WP_REST_Posts_Controller::prepare_links()

Prepares links for the request.

wp-includes/rest-api/endpoints/class-wp-rest-posts-controller.php:WP_REST_Posts_Controller::get_items()

Retrieves a collection of posts.

wp-includes/rest-api/endpoints/class-wp-rest-comments-controller.php:WP_REST_Comments_Controller::prepare_links()

Prepares links for the request.

wp-includes/rest-api/endpoints/class-wp-rest-comments-controller.php:WP_REST_Comments_Controller::get_items()

Retrieves a list of comment items.

wp-includes/link-template.php:wp_get_canonical_url()

Returns the canonical URL for a post.

wp-admin/includes/ms.php:network_edit_site_nav()

Outputs the HTML for a network’s “Edit Site” tabular interface.

wp-admin/includes/ajax-actions.php:wp_ajax_search_install_plugins()

Ajax handler for searching plugins to install.

wp-admin/includes/ajax-actions.php:wp_ajax_search_plugins()

Ajax handler for searching plugins.

wp-admin/includes/ajax-actions.php:wp_ajax_install_theme()

Ajax handler for installing a theme.

wp-admin/includes/ajax-actions.php:wp_ajax_install_plugin()

Ajax handler for installing a plugin.

wp-includes/rest-api.php:get_rest_url()

Retrieves the URL to a REST endpoint on a site.

wp-includes/embed.php:get_post_embed_url()

Retrieves the URL to embed a specific post in an iframe.

wp-includes/embed.php:get_oembed_endpoint_url()

Retrieves the oEmbed endpoint URL for a given permalink.

wp-includes/class-wp-customize-manager.php:WP_Customize_Manager::customize_pane_settings()

Prints JavaScript settings for parent window.

wp-includes/link-template.php:get_preview_post_link()

Retrieves the URL used for the post preview.

wp-admin/includes/class-wp-posts-list-table.php:WP_Posts_List_Table::get_edit_link()

Helper to create links to edit.php with params.

wp-includes/admin-bar.php:wp_admin_bar_customize_menu()

Adds the “Customize” link to the Toolbar.

wp-admin/includes/class-wp-ms-themes-list-table.php:WP_MS_Themes_List_Table::column_name()

Handles the name column output.

wp-admin/includes/class-wp-terms-list-table.php:WP_Terms_List_Table::handle_row_actions()

Generates and displays row action links.

wp-admin/includes/class-wp-ms-users-list-table.php:WP_MS_Users_List_Table::handle_row_actions()

Generates and displays row action links.

wp-admin/includes/class-wp-ms-users-list-table.php:WP_MS_Users_List_Table::column_username()

Handles the username column output.

wp-admin/includes/class-wp-media-list-table.php:WP_Media_List_Table::column_author()

Handles the author column output.

wp-admin/includes/class-wp-media-list-table.php:WP_Media_List_Table::column_parent()

Handles the parent column output.

wp-admin/includes/class-wp-media-list-table.php:WP_Media_List_Table::column_default()

Handles output for the default column.

wp-includes/link-template.php:get_avatar_data()

Retrieves default data about the avatar.

wp-admin/includes/media.php:wp_media_attach_action()

Encapsulates the logic for Attach/Detach actions.

wp-admin/includes/theme.php:wp_prepare_themes_for_js()

Prepares themes for JavaScript.

wp-admin/includes/theme.php:get_theme_update_available()

Retrieves the update link if there is a theme update available.

wp-admin/includes/theme.php:themes_api()

Retrieves theme installer pages from the WordPress.org Themes API.

wp-admin/includes/class-wp-plugins-list-table.php:WP_Plugins_List_Table::get_views()
wp-admin/includes/class-wp-plugins-list-table.php:WP_Plugins_List_Table::single_row()
wp-admin/includes/class-wp-plugins-list-table.php:WP_Plugins_List_Table::__construct()

Constructor.

wp-admin/includes/class-theme-upgrader-skin.php:Theme_Upgrader_Skin::after()

Action to perform following a single theme update.

wp-admin/includes/class-theme-installer-skin.php:Theme_Installer_Skin::after()

Action to perform following a single theme install.

wp-admin/includes/class-wp-list-table.php:WP_List_Table::view_switcher()

Displays a view switcher.

wp-admin/includes/class-wp-list-table.php:WP_List_Table::comments_bubble()

Displays a comment count bubble.

wp-admin/includes/class-wp-list-table.php:WP_List_Table::pagination()

Displays the pagination.

wp-admin/includes/class-wp-list-table.php:WP_List_Table::print_column_headers()

Prints column headers, accounting for hidden and sortable columns.

wp-admin/includes/class-wp-list-table.php:WP_List_Table::set_pagination_args()

An internal method that sets all the necessary pagination arguments

wp-admin/includes/class-wp-ms-themes-list-table.php:WP_MS_Themes_List_Table::get_views()
wp-admin/includes/misc.php:set_screen_options()

Saves option for number of rows when listing posts, pages, comments, etc.

wp-admin/includes/class-wp-theme-install-list-table.php:WP_Theme_Install_List_Table::install_theme_info()

Prints the info for a theme (to be used in the theme installer modal).

wp-admin/includes/class-wp-theme-install-list-table.php:WP_Theme_Install_List_Table::single_row()

Prints a theme from the WordPress.org API.

wp-admin/includes/update.php:wp_plugin_update_row()

Displays update information for a plugin.

wp-admin/includes/update.php:wp_theme_update_row()

Displays update information for a theme.

wp-admin/includes/plugin-install.php:install_plugin_information()

Displays plugin information in dialog box form.

wp-admin/includes/plugin-install.php:plugins_api()

Retrieves plugin installer pages from the WordPress.org Plugins API.

wp-admin/includes/dashboard.php:wp_dashboard_browser_nag()

Displays the browser update nag.

wp-admin/includes/dashboard.php:wp_add_dashboard_widget()

Adds a new dashboard widget.

wp-admin/includes/plugin.php:menu_page_url()

Gets the URL to access a particular menu page based on the slug it was registered with.

wp-admin/includes/plugin.php:activate_plugin()

Attempts activation of plugin in a “sandbox” and redirects on success.

wp-admin/includes/plugin.php:activate_plugins()

Activates multiple plugins.

wp-admin/includes/class-wp-plugin-install-list-table.php:WP_Plugin_Install_List_Table::display_rows()
wp-admin/includes/class-wp-users-list-table.php:WP_Users_List_Table::single_row()

Generate HTML for a single row on the users.php admin panel.

wp-admin/includes/class-wp-users-list-table.php:WP_Users_List_Table::get_views()

Return an associative array listing all the views that can be used with this table.

wp-admin/includes/media.php:media_upload_library_form()

Outputs the legacy media upload form for the media library.

wp-admin/includes/media.php:the_media_upload_tabs()

Outputs the legacy media upload tabs UI.

wp-admin/includes/media.php:get_upload_iframe_src()
wp-admin/includes/post.php:_admin_notice_post_locked()

Outputs the HTML for the notice to say that someone else is editing or has taken over editing of this post.

wp-admin/includes/ajax-actions.php:wp_ajax_query_themes()

Ajax handler for getting themes from themes_api().

wp-admin/includes/revision.php:wp_prepare_revisions_for_js()

Prepare revisions for JavaScript.

wp-admin/includes/meta-boxes.php:post_submit_meta_box()

Displays post submit form fields.

wp-admin/includes/class-wp-comments-list-table.php:WP_Comments_List_Table::column_author()
wp-admin/includes/class-wp-comments-list-table.php:WP_Comments_List_Table::get_views()
wp-admin/includes/class-wp-terms-list-table.php:WP_Terms_List_Table::column_name()
wp-admin/includes/class-wp-terms-list-table.php:WP_Terms_List_Table::column_posts()
wp-admin/includes/class-walker-nav-menu-edit.php:Walker_Nav_Menu_Edit::start_el()

Start the element output.

wp-admin/includes/nav-menu.php:wp_nav_menu_item_post_type_meta_box()

Displays a meta box for a post type menu item.

wp-admin/includes/nav-menu.php:wp_nav_menu_item_taxonomy_meta_box()

Displays a meta box for a taxonomy menu item.

wp-admin/includes/widgets.php:wp_widget_control()

Meta widget used to display the control form for a widget.

wp-admin/includes/import.php:wp_get_popular_importers()

Returns a list from WordPress.org of popular importer plugins.

wp-admin/includes/class-custom-image-header.php:Custom_Image_Header::step_1()

Display first step of custom header image page.

wp-admin/includes/class-custom-image-header.php:Custom_Image_Header::step_2()

Display second step of custom header image page.

wp-admin/includes/post.php:redirect_post()

Redirects to previous page.

wp-admin/menu-header.php:_wp_menu_output()

Display menu.

wp-includes/class.wp-styles.php:WP_Styles::_css_href()

Generates an enqueued style’s fully-qualified URL.

wp-includes/cron.php:spawn_cron()

Sends a request to run cron through HTTP request that doesn’t halt page loading.

wp-includes/general-template.php:paginate_links()

Retrieves paginated links for archive post pages.

wp-includes/general-template.php:wp_admin_css_uri()

Displays the URL of a WordPress admin CSS file.

wp-includes/general-template.php:wp_get_archives()

Display archive links based on type and format.

wp-includes/general-template.php:wp_logout_url()

Retrieves the logout URL.

wp-includes/general-template.php:wp_login_url()

Retrieves the login URL.

wp-includes/general-template.php:wp_lostpassword_url()

Returns the URL that allows the user to retrieve the lost password

wp-includes/deprecated.php:dropdown_cats()

Deprecated method for generating a drop-down of categories.

wp-includes/deprecated.php:wp_get_links()

Gets the links associated with category.

wp-includes/functions.php:wp_auth_check_html()

Output the HTML that shows the wp-login dialog when the user is no longer logged in.

wp-includes/functions.php:wp_nonce_url()

Retrieve URL with nonce added to URL query.

wp-includes/functions.php:remove_query_arg()

Removes an item or items from a query string.

wp-includes/link-template.php:get_comments_pagenum_link()

Retrieves the comments page number link.

wp-includes/link-template.php:paginate_comments_links()

Displays or retrieves pagination links for the comments on the current post.

wp-includes/link-template.php:get_pagenum_link()

Retrieves the link for a page number.

wp-includes/link-template.php:get_edit_user_link()

Retrieves the edit user link.

wp-includes/link-template.php:get_search_comments_feed_link()

Retrieves the permalink for the search results comments feed.

wp-includes/link-template.php:get_post_type_archive_feed_link()

Retrieves the permalink for a post type archive feed.

wp-includes/link-template.php:get_delete_post_link()

Retrieves the delete posts link for post.

wp-includes/link-template.php:get_edit_term_link()

Retrieves the URL for editing a given term.

wp-includes/link-template.php:get_search_feed_link()

Retrieves the permalink for the search results feed.

wp-includes/link-template.php:get_post_comments_feed_link()

Retrieves the permalink for the post comments feed.

wp-includes/link-template.php:get_post_permalink()

Retrieves the permalink for a post of a custom post type.

wp-includes/class-wp-oembed.php:WP_oEmbed::fetch()

Connects to a oEmbed provider and returns the result.

wp-includes/class-wp-oembed.php:WP_oEmbed::_fetch_with_format()

Fetches result from an oEmbed provider for a specific format and complete provider URL

wp-includes/post-template.php:_wp_link_page()

Helper function for wp_link_pages().

wp-includes/media.php:wp_enqueue_media()

Enqueues all scripts, styles, settings, and templates necessary to use all media JS APIs.

wp-includes/media.php:wp_video_shortcode()

Builds the Video shortcode output.

wp-includes/media.php:wp_audio_shortcode()

Builds the Audio shortcode output.

wp-includes/class-wp-rewrite.php:WP_Rewrite::add_rule()

Adds a rewrite rule that transforms a URL structure to a set of query vars.

wp-includes/canonical.php:redirect_canonical()

Redirects incoming links to the proper URL based on the site url.

wp-includes/post-formats.php:_post_format_link()

Filters the post format term link to remove the format prefix.

wp-includes/class.wp-scripts.php:WP_Scripts::do_item()

Processes a script dependency.

wp-includes/comment-template.php:get_comment_reply_link()

Retrieves HTML content for reply to comment link.

wp-includes/comment-template.php:get_comment_link()

Retrieves the link to a given comment.

wp-includes/script-loader.php:wp_style_loader_src()

Administration Screen CSS for changing the styles.

wp-includes/media-template.php:wp_print_media_templates()

Prints the templates used in the media manager.

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Changelog

Changelog
VersionDescription
5.3.0Formalized the existing and already documented parameters by adding ...$args to the function signature.
1.5.0Introduced.
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