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<?php |
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/* |
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Plugin Name: Canonical Link |
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Plugin URI: https://webguy.io/blog/super-simple-dynamic-canonical-link-code/ |
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Description: Adds the canonical link to your site (https://wikipedia.org/wiki/Canonical_link_element). Activate and then set your permalinks to "Post name" under Settings > Permalinks. That's it. Verify that it's working correctly with the Firefox add-on: https://addons.mozilla.org/addon/canonical-link/. |
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Version: 1.7 |
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Requires at least: 5.0 |
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Author: Web Guy |
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Author URI: https://webguy.io/ |
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License: CC0 |
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License URI: https://creativecommons.org/public-domain/cc0/ |
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Text Domain: canonical-link |
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*/ |
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|
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if ( !defined( 'ABSPATH' ) ) { |
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http_response_code( 404 ); |
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die(); |
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} |
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|
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if ( is_admin() ) { |
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add_action( 'add_meta_boxes', 'canonicalink_meta_box_add' ); |
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function canonicalink_meta_box_add() { |
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$post_types = get_post_types( array( 'public' => true ) ); |
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add_meta_box( 'canonicalink_post', 'Canonical Link', 'canonicalink_post_meta_box', $post_types, 'normal', 'high' ); |
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} |
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function canonicalink_post_meta_box( $post ) { |
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$values = get_post_custom( $post->ID ); |
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$canonicalink_custom_url = ''; |
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if ( isset( $values['canonicalink_custom'] ) ) { |
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$canonicalink_custom_url = esc_url( $values['canonicalink_custom'][0] ); |
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} |
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wp_nonce_field( 'canonicalink_meta_box_nonce', 'meta_box_nonce' ); |
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?> |
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<p><input type="text" name="canonicalink_custom" class="large-text" placeholder="https://example.com/" value="<?php if ( $canonicalink_custom = get_post_meta( $post->ID, 'canonicalink_custom', true ) ) { echo esc_url( $canonicalink_custom_url ); } ?>"></p> |
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<?php |
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} |
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add_action( 'save_post', 'canonicalink_meta_box_save' ); |
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function canonicalink_meta_box_save( $post_id ) { |
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if ( defined( 'DOING_AUTOSAVE' ) && DOING_AUTOSAVE ) return; |
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if ( !isset( $_POST['meta_box_nonce'] ) || !wp_verify_nonce( sanitize_text_field( wp_unslash( $_POST['meta_box_nonce'] ) ), 'canonicalink_meta_box_nonce' ) ) return; |
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if ( !current_user_can( 'edit_post', $post_id ) ) return; |
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if ( isset( $_POST['canonicalink_custom'] ) ) { |
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update_post_meta( $post_id, 'canonicalink_custom', esc_url_raw( wp_unslash( $_POST['canonicalink_custom'] ) ) ); |
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} |
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} |
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} |
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|
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add_action( 'wp_head', 'canonicalink', 1 ); |
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function canonicalink() { |
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global $post; |
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if ( !$post ) return; |
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$canonicalink_custom_url = ''; |
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$values = get_post_custom( $post->ID ); |
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if ( isset( $values['canonicalink_custom'] ) ) { |
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$canonicalink_custom_url = esc_url( $values['canonicalink_custom'][0] ); |
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} |
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if ( ( is_singular() ) && ( $canonicalink_custom = get_post_meta( $post->ID, 'canonicalink_custom', true ) ) ) { |
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echo '<link rel="canonical" href="' . esc_url( $canonicalink_custom_url ) . '">'; |
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} else { |
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echo '<link rel="canonical" href="' . esc_url( ( isset( $_SERVER['HTTPS'] ) ? 'https' : 'http' ) . '://' . ( isset( $_SERVER['HTTP_HOST'] ) ? sanitize_text_field( wp_unslash( $_SERVER['HTTP_HOST'] ) ) : '' ) . wp_parse_url( isset( $_SERVER['REQUEST_URI'] ) ? sanitize_url( wp_unslash( $_SERVER['REQUEST_URI'] ) ) : '', PHP_URL_PATH ) ) . '">'; |
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} |
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} |
