wp_insert_term

wp_insert_term: 這個函式用來在資料庫中插入一個新的術語。它接收一個術語資料陣列作為引數，並返回新術語的ID。

向資料庫新增一個新術語。

一個不存在的術語是按以下順序插入的。
1. 該術語被新增到術語表中，然後與分類法相關。
2. 2.如果一切正確，則啟動幾個動作。
3. 3.”term_id_filter”被評估。
4. 4.術語快取被清理。
5. 還有幾個動作被啟動。
6. 6. 返回一個包含`term_id`和`term_taxonomy_id`的陣列。

如果’slug’引數不是空的，那麼將檢查該術語是否是無效的。如果它不是一個有效的、現有的術語，它將被新增，並給出術語_id。

如果分類法是分層的，並且’parent’引數不是空的，那麼該術語會被插入，並且會給出term_id。

錯誤處理。
如果`$taxonomy`不存在或者`$term`為空，將返回一個WP_Error物件。

如果該術語已經存在於同一層次上，或者該術語的slug和名稱不唯一，將返回一個WP_Error物件。

function wp_insert_term( $term, $taxonomy, $args = array() ) {
	global $wpdb;

	if ( ! taxonomy_exists( $taxonomy ) ) {
		return new WP_Error( 'invalid_taxonomy', __( 'Invalid taxonomy.' ) );
	}

	/**
	 * Filters a term before it is sanitized and inserted into the database.
	 *
	 * @since 3.0.0
	 * @since 6.1.0 The `$args` parameter was added.
	 *
	 * @param string|WP_Error $term     The term name to add, or a WP_Error object if there's an error.
	 * @param string          $taxonomy Taxonomy slug.
	 * @param array|string    $args     Array or query string of arguments passed to wp_insert_term().
	 */
	$term = apply_filters( 'pre_insert_term', $term, $taxonomy, $args );

	if ( is_wp_error( $term ) ) {
		return $term;
	}

	if ( is_int( $term ) && 0 === $term ) {
		return new WP_Error( 'invalid_term_id', __( 'Invalid term ID.' ) );
	}

	if ( '' === trim( $term ) ) {
		return new WP_Error( 'empty_term_name', __( 'A name is required for this term.' ) );
	}

	$defaults = array(
		'alias_of'    => '',
		'description' => '',
		'parent'      => 0,
		'slug'        => '',
	);
	$args     = wp_parse_args( $args, $defaults );

	if ( (int) $args['parent'] > 0 && ! term_exists( (int) $args['parent'] ) ) {
		return new WP_Error( 'missing_parent', __( 'Parent term does not exist.' ) );
	}

	$args['name']     = $term;
	$args['taxonomy'] = $taxonomy;

	// Coerce null description to strings, to avoid database errors.
	$args['description'] = (string) $args['description'];

	$args = sanitize_term( $args, $taxonomy, 'db' );

	// expected_slashed ($name)
	$name        = wp_unslash( $args['name'] );
	$description = wp_unslash( $args['description'] );
	$parent      = (int) $args['parent'];

	$slug_provided = ! empty( $args['slug'] );
	if ( ! $slug_provided ) {
		$slug = sanitize_title( $name );
	} else {
		$slug = $args['slug'];
	}

	$term_group = 0;
	if ( $args['alias_of'] ) {
		$alias = get_term_by( 'slug', $args['alias_of'], $taxonomy );
		if ( ! empty( $alias->term_group ) ) {
			// The alias we want is already in a group, so let's use that one.
			$term_group = $alias->term_group;
		} elseif ( ! empty( $alias->term_id ) ) {
			/*
			 * The alias is not in a group, so we create a new one
			 * and add the alias to it.
			 */
			$term_group = $wpdb->get_var( "SELECT MAX(term_group) FROM $wpdb->terms" ) + 1;

			wp_update_term(
				$alias->term_id,
				$taxonomy,
				array(
					'term_group' => $term_group,
				)
			);
		}
	}

	/*
	 * Prevent the creation of terms with duplicate names at the same level of a taxonomy hierarchy,
	 * unless a unique slug has been explicitly provided.
	 */
	$name_matches = get_terms(
		array(
			'taxonomy'               => $taxonomy,
			'name'                   => $name,
			'hide_empty'             => false,
			'parent'                 => $args['parent'],
			'update_term_meta_cache' => false,
		)
	);

	/*
	 * The `name` match in `get_terms()` doesn't differentiate accented characters,
	 * so we do a stricter comparison here.
	 */
	$name_match = null;
	if ( $name_matches ) {
		foreach ( $name_matches as $_match ) {
			if ( strtolower( $name ) === strtolower( $_match->name ) ) {
				$name_match = $_match;
				break;
			}
		}
	}

	if ( $name_match ) {
		$slug_match = get_term_by( 'slug', $slug, $taxonomy );
		if ( ! $slug_provided || $name_match->slug === $slug || $slug_match ) {
			if ( is_taxonomy_hierarchical( $taxonomy ) ) {
				$siblings = get_terms(
					array(
						'taxonomy'               => $taxonomy,
						'get'                    => 'all',
						'parent'                 => $parent,
						'update_term_meta_cache' => false,
					)
				);

				$existing_term = null;
				$sibling_names = wp_list_pluck( $siblings, 'name' );
				$sibling_slugs = wp_list_pluck( $siblings, 'slug' );

				if ( ( ! $slug_provided || $name_match->slug === $slug ) && in_array( $name, $sibling_names, true ) ) {
					$existing_term = $name_match;
				} elseif ( $slug_match && in_array( $slug, $sibling_slugs, true ) ) {
					$existing_term = $slug_match;
				}

				if ( $existing_term ) {
					return new WP_Error( 'term_exists', __( 'A term with the name provided already exists with this parent.' ), $existing_term->term_id );
				}
			} else {
				return new WP_Error( 'term_exists', __( 'A term with the name provided already exists in this taxonomy.' ), $name_match->term_id );
			}
		}
	}

	$slug = wp_unique_term_slug( $slug, (object) $args );

	$data = compact( 'name', 'slug', 'term_group' );

	/**
	 * Filters term data before it is inserted into the database.
	 *
	 * @since 4.7.0
	 *
	 * @param array  $data     Term data to be inserted.
	 * @param string $taxonomy Taxonomy slug.
	 * @param array  $args     Arguments passed to wp_insert_term().
	 */
	$data = apply_filters( 'wp_insert_term_data', $data, $taxonomy, $args );

	if ( false === $wpdb->insert( $wpdb->terms, $data ) ) {
		return new WP_Error( 'db_insert_error', __( 'Could not insert term into the database.' ), $wpdb->last_error );
	}

	$term_id = (int) $wpdb->insert_id;

	// Seems unreachable. However, is used in the case that a term name is provided, which sanitizes to an empty string.
	if ( empty( $slug ) ) {
		$slug = sanitize_title( $slug, $term_id );

		/** This action is documented in wp-includes/taxonomy.php */
		do_action( 'edit_terms', $term_id, $taxonomy );
		$wpdb->update( $wpdb->terms, compact( 'slug' ), compact( 'term_id' ) );

		/** This action is documented in wp-includes/taxonomy.php */
		do_action( 'edited_terms', $term_id, $taxonomy );
	}

	$tt_id = $wpdb->get_var( $wpdb->prepare( "SELECT tt.term_taxonomy_id FROM $wpdb->term_taxonomy AS tt INNER JOIN $wpdb->terms AS t ON tt.term_id = t.term_id WHERE tt.taxonomy = %s AND t.term_id = %d", $taxonomy, $term_id ) );

	if ( ! empty( $tt_id ) ) {
		return array(
			'term_id'          => $term_id,
			'term_taxonomy_id' => $tt_id,
		);
	}

	if ( false === $wpdb->insert( $wpdb->term_taxonomy, compact( 'term_id', 'taxonomy', 'description', 'parent' ) + array( 'count' => 0 ) ) ) {
		return new WP_Error( 'db_insert_error', __( 'Could not insert term taxonomy into the database.' ), $wpdb->last_error );
	}

	$tt_id = (int) $wpdb->insert_id;

	/*
	 * Sanity check: if we just created a term with the same parent + taxonomy + slug but a higher term_id than
	 * an existing term, then we have unwittingly created a duplicate term. Delete the dupe, and use the term_id
	 * and term_taxonomy_id of the older term instead. Then return out of the function so that the "create" hooks
	 * are not fired.
	 */
	$duplicate_term = $wpdb->get_row( $wpdb->prepare( "SELECT t.term_id, t.slug, tt.term_taxonomy_id, tt.taxonomy FROM $wpdb->terms AS t INNER JOIN $wpdb->term_taxonomy AS tt ON ( tt.term_id = t.term_id ) WHERE t.slug = %s AND tt.parent = %d AND tt.taxonomy = %s AND t.term_id < %d AND tt.term_taxonomy_id != %d", $slug, $parent, $taxonomy, $term_id, $tt_id ) );

	/**
	 * Filters the duplicate term check that takes place during term creation.
	 *
	 * Term parent + taxonomy + slug combinations are meant to be unique, and wp_insert_term()
	 * performs a last-minute confirmation of this uniqueness before allowing a new term
	 * to be created. Plugins with different uniqueness requirements may use this filter
	 * to bypass or modify the duplicate-term check.
	 *
	 * @since 5.1.0
	 *
	 * @param object $duplicate_term Duplicate term row from terms table, if found.
	 * @param string $term           Term being inserted.
	 * @param string $taxonomy       Taxonomy name.
	 * @param array  $args           Arguments passed to wp_insert_term().
	 * @param int    $tt_id          term_taxonomy_id for the newly created term.
	 */
	$duplicate_term = apply_filters( 'wp_insert_term_duplicate_term_check', $duplicate_term, $term, $taxonomy, $args, $tt_id );

	if ( $duplicate_term ) {
		$wpdb->delete( $wpdb->terms, array( 'term_id' => $term_id ) );
		$wpdb->delete( $wpdb->term_taxonomy, array( 'term_taxonomy_id' => $tt_id ) );

		$term_id = (int) $duplicate_term->term_id;
		$tt_id   = (int) $duplicate_term->term_taxonomy_id;

		clean_term_cache( $term_id, $taxonomy );
		return array(
			'term_id'          => $term_id,
			'term_taxonomy_id' => $tt_id,
		);
	}

	/**
	 * Fires immediately after a new term is created, before the term cache is cleaned.
	 *
	 * The {@see 'create_$taxonomy'} hook is also available for targeting a specific
	 * taxonomy.
	 *
	 * @since 2.3.0
	 * @since 6.1.0 The `$args` parameter was added.
	 *
	 * @param int    $term_id  Term ID.
	 * @param int    $tt_id    Term taxonomy ID.
	 * @param string $taxonomy Taxonomy slug.
	 * @param array  $args     Arguments passed to wp_insert_term().
	 */
	do_action( 'create_term', $term_id, $tt_id, $taxonomy, $args );

	/**
	 * Fires after a new term is created for a specific taxonomy.
	 *
	 * The dynamic portion of the hook name, `$taxonomy`, refers
	 * to the slug of the taxonomy the term was created for.
	 *
	 * Possible hook names include:
	 *
	 *  - `create_category`
	 *  - `create_post_tag`
	 *
	 * @since 2.3.0
	 * @since 6.1.0 The `$args` parameter was added.
	 *
	 * @param int   $term_id Term ID.
	 * @param int   $tt_id   Term taxonomy ID.
	 * @param array $args    Arguments passed to wp_insert_term().
	 */
	do_action( "create_{$taxonomy}", $term_id, $tt_id, $args );

	/**
	 * Filters the term ID after a new term is created.
	 *
	 * @since 2.3.0
	 * @since 6.1.0 The `$args` parameter was added.
	 *
	 * @param int   $term_id Term ID.
	 * @param int   $tt_id   Term taxonomy ID.
	 * @param array $args    Arguments passed to wp_insert_term().
	 */
	$term_id = apply_filters( 'term_id_filter', $term_id, $tt_id, $args );

	clean_term_cache( $term_id, $taxonomy );

	/**
	 * Fires after a new term is created, and after the term cache has been cleaned.
	 *
	 * The {@see 'created_$taxonomy'} hook is also available for targeting a specific
	 * taxonomy.
	 *
	 * @since 2.3.0
	 * @since 6.1.0 The `$args` parameter was added.
	 *
	 * @param int    $term_id  Term ID.
	 * @param int    $tt_id    Term taxonomy ID.
	 * @param string $taxonomy Taxonomy slug.
	 * @param array  $args     Arguments passed to wp_insert_term().
	 */
	do_action( 'created_term', $term_id, $tt_id, $taxonomy, $args );

	/**
	 * Fires after a new term in a specific taxonomy is created, and after the term
	 * cache has been cleaned.
	 *
	 * The dynamic portion of the hook name, `$taxonomy`, refers to the taxonomy slug.
	 *
	 * Possible hook names include:
	 *
	 *  - `created_category`
	 *  - `created_post_tag`
	 *
	 * @since 2.3.0
	 * @since 6.1.0 The `$args` parameter was added.
	 *
	 * @param int   $term_id Term ID.
	 * @param int   $tt_id   Term taxonomy ID.
	 * @param array $args    Arguments passed to wp_insert_term().
	 */
	do_action( "created_{$taxonomy}", $term_id, $tt_id, $args );

	/**
	 * Fires after a term has been saved, and the term cache has been cleared.
	 *
	 * The {@see 'saved_$taxonomy'} hook is also available for targeting a specific
	 * taxonomy.
	 *
	 * @since 5.5.0
	 * @since 6.1.0 The `$args` parameter was added.
	 *
	 * @param int    $term_id  Term ID.
	 * @param int    $tt_id    Term taxonomy ID.
	 * @param string $taxonomy Taxonomy slug.
	 * @param bool   $update   Whether this is an existing term being updated.
	 * @param array  $args     Arguments passed to wp_insert_term().
	 */
	do_action( 'saved_term', $term_id, $tt_id, $taxonomy, false, $args );

	/**
	 * Fires after a term in a specific taxonomy has been saved, and the term
	 * cache has been cleared.
	 *
	 * The dynamic portion of the hook name, `$taxonomy`, refers to the taxonomy slug.
	 *
	 * Possible hook names include:
	 *
	 *  - `saved_category`
	 *  - `saved_post_tag`
	 *
	 * @since 5.5.0
	 * @since 6.1.0 The `$args` parameter was added.
	 *
	 * @param int   $term_id Term ID.
	 * @param int   $tt_id   Term taxonomy ID.
	 * @param bool  $update  Whether this is an existing term being updated.
	 * @param array $args    Arguments passed to wp_insert_term().
	 */
	do_action( "saved_{$taxonomy}", $term_id, $tt_id, false, $args );

	return array(
		'term_id'          => $term_id,
		'term_taxonomy_id' => $tt_id,
	);
}