WordPress · JanJakes · Jul 7, 2025 · Jul 7, 2025 · Jul 7, 2025 · Jul 8, 2025
diff --git a/activate.php b/activate.php
@@ -82,6 +82,28 @@ function sqlite_plugin_copy_db_file() {
 
 	$destination = WP_CONTENT_DIR . '/db.php';
 
+	/*
+	 * When an existing "db.php" drop-in is detected, let's check if it's a known
+	 * plugin that we can continue supporting even when we override the drop-in.
+	 */
+	$override_db_dropin = false;
+	if ( file_exists( $destination ) ) {
+		// Check for the Query Monitor plugin.
+		// When "QM_DB" exists, it must have been loaded via the "db.php" file.
+		if ( class_exists( 'QM_DB', false ) ) {
+			$override_db_dropin = true;
+		}
+
+		if ( $override_db_dropin ) {
+			require_once ABSPATH . '/wp-admin/includes/file.php';
+			global $wp_filesystem;
+			if ( ! $wp_filesystem ) {
+				WP_Filesystem();
+			}
+			$wp_filesystem->delete( $destination );
+		}
+	}
+
 	// Place database drop-in if not present yet, except in case there is
 	// another database drop-in present already.
 	if ( ! defined( 'SQLITE_DB_DROPIN_VERSION' ) && ! file_exists( $destination ) ) {

diff --git a/admin-page.php b/admin-page.php
@@ -26,6 +26,21 @@ function sqlite_add_admin_menu() {
  * The admin page contents.
  */
 function sqlite_integration_admin_screen() {
+	$db_dropin_path = WP_CONTENT_DIR . '/db.php';
+
+	/*
+	 * When an existing "db.php" drop-in is detected, let's check if it's a known
+	 * plugin that we can continue supporting even when we override the drop-in.
+	 */
+	$override_db_dropin = false;
+	if ( file_exists( $db_dropin_path ) && ! defined( 'SQLITE_DB_DROPIN_VERSION' ) ) {
+		// Check for the Query Monitor plugin.
+		// When "QM_DB" exists, it must have been loaded via the "db.php" file.
+		if ( class_exists( 'QM_DB', false ) ) {
+			$override_db_dropin = true;
+		}
+	}
+
 	?>
 	<div class="wrap">
 		<h1><?php esc_html_e( 'SQLite integration.', 'sqlite-database-integration' ); ?></h1>
@@ -46,68 +61,82 @@ function sqlite_integration_admin_screen() {
 					);
 				?>
 			</p>
-		<?php else : ?>
-			<?php if ( ! extension_loaded( 'pdo_sqlite' ) ) : ?>
-				<div class="notice notice-error">
-					<p><?php esc_html_e( 'We detected that the PDO SQLite driver is missing from your server (the pdo_sqlite extension is not loaded). Please make sure that SQLite is enabled in your PHP installation before proceeding.', 'sqlite-database-integration' ); ?></p>
-				</div>
-			<?php elseif ( file_exists( WP_CONTENT_DIR . '/db.php' ) && ! defined( 'SQLITE_DB_DROPIN_VERSION' ) ) : ?>
-				<?php if ( defined( 'PERFLAB_SQLITE_DB_DROPIN_VERSION' ) ) : ?>
-					<div class="notice notice-warning">
-						<p>
-							<?php
-							printf(
-								/* translators: %s: db.php drop-in path */
-								esc_html__( 'An older %s file was detected. Please click the button below to update the file.', 'sqlite-database-integration' ),
-								'<code>' . esc_html( basename( WP_CONTENT_DIR ) ) . '/db.php</code>'
-							);
-							?>
-						</p>
-					</div>
-					<a class="button button-primary" href="<?php echo esc_url( wp_nonce_url( admin_url( 'admin.php?page=sqlite-integration&confirm-install&upgrade-from-pl' ), 'sqlite-install' ) ); ?>">
+		<?php elseif ( ! extension_loaded( 'pdo_sqlite' ) ) : ?>
+			<div class="notice notice-error">
+				<p><?php esc_html_e( 'We detected that the PDO SQLite driver is missing from your server (the pdo_sqlite extension is not loaded). Please make sure that SQLite is enabled in your PHP installation before proceeding.', 'sqlite-database-integration' ); ?></p>
+			</div>
+		<?php elseif ( file_exists( $db_dropin_path ) && ! defined( 'SQLITE_DB_DROPIN_VERSION' ) && ! $override_db_dropin ) : ?>
+			<?php if ( defined( 'PERFLAB_SQLITE_DB_DROPIN_VERSION' ) ) : ?>
+				<div class="notice notice-warning">
+					<p>
 						<?php
 						printf(
 							/* translators: %s: db.php drop-in path */
-							esc_html__( 'Update %s file', 'sqlite-database-integration' ),
+							esc_html__( 'An older %s file was detected. Please click the button below to update the file.', 'sqlite-database-integration' ),
 							'<code>' . esc_html( basename( WP_CONTENT_DIR ) ) . '/db.php</code>'
 						);
 						?>
-					</a>
-				<?php else : ?>
-					<div class="notice notice-error">
-						<p>
-							<?php
-							printf(
-								/* translators: %s: db.php drop-in path */
-								esc_html__( 'The SQLite plugin cannot be activated because a different %s drop-in already exists.', 'sqlite-database-integration' ),
-								'<code>' . esc_html( basename( WP_CONTENT_DIR ) ) . '/db.php</code>'
-							);
-							?>
-						</p>
-					</div>
-				<?php endif; ?>
-			<?php elseif ( ! is_writable( WP_CONTENT_DIR ) ) : ?>
+					</p>
+				</div>
+				<a class="button button-primary" href="<?php echo esc_url( wp_nonce_url( admin_url( 'admin.php?page=sqlite-integration&confirm-install&upgrade-from-pl' ), 'sqlite-install' ) ); ?>">
+					<?php
+					printf(
+						/* translators: %s: db.php drop-in path */
+						esc_html__( 'Update %s file', 'sqlite-database-integration' ),
+						'<code>' . esc_html( basename( WP_CONTENT_DIR ) ) . '/db.php</code>'
+					);
+					?>
+				</a>
+			<?php else : ?>
 				<div class="notice notice-error">
 					<p>
 						<?php
 						printf(
 							/* translators: %s: db.php drop-in path */
-							esc_html__( 'The SQLite plugin cannot be activated because the %s directory is not writable.', 'sqlite-database-integration' ),
-							'<code>' . esc_html( basename( WP_CONTENT_DIR ) ) . '</code>'
+							esc_html__( 'The SQLite plugin cannot be activated because a different %s drop-in already exists.', 'sqlite-database-integration' ),
+							'<code>' . esc_html( basename( WP_CONTENT_DIR ) ) . '/db.php</code>'
 						);
 						?>
 					</p>
 				</div>
-			<?php else : ?>
-				<div class="notice notice-success">
-					<p><?php esc_html_e( 'All checks completed successfully, your site can use an SQLite database. You can proceed with the installation.', 'sqlite-database-integration' ); ?></p>
-				</div>
-				<h2><?php esc_html_e( 'Important note', 'sqlite-database-integration' ); ?></h2>
-				<p><?php esc_html_e( 'This plugin will switch to a separate database and install WordPress in it. You will need to reconfigure your site, and start with a fresh site. Disabling the plugin you will get back to your previous MySQL database, with all your previous data intact.', 'sqlite-database-integration' ); ?></p>
-				<p><?php esc_html_e( 'By clicking the button below, you will be redirected to the WordPress installation screen to setup your new database', 'sqlite-database-integration' ); ?></p>
+			<?php endif; ?>
+		<?php elseif ( ! is_writable( WP_CONTENT_DIR ) ) : ?>
+			<div class="notice notice-error">
+				<p>
+					<?php
+					printf(
+						/* translators: %s: db.php drop-in path */
+						esc_html__( 'The SQLite plugin cannot be activated because the %s directory is not writable.', 'sqlite-database-integration' ),
+						'<code>' . esc_html( basename( WP_CONTENT_DIR ) ) . '</code>'
+					);
+					?>
+				</p>
+			</div>
+		<?php else : ?>
+			<div class="notice notice-success">
+				<p><?php esc_html_e( 'All checks completed successfully, your site can use an SQLite database. You can proceed with the installation.', 'sqlite-database-integration' ); ?></p>
+			</div>
+			<h2><?php esc_html_e( 'Important note', 'sqlite-database-integration' ); ?></h2>
+			<p><?php esc_html_e( 'This plugin will switch to a separate database and install WordPress in it. You will need to reconfigure your site, and start with a fresh site. Disabling the plugin you will get back to your previous MySQL database, with all your previous data intact.', 'sqlite-database-integration' ); ?></p>
 
-				<a class="button button-primary" href="<?php echo esc_url( wp_nonce_url( admin_url( 'admin.php?page=sqlite-integration&confirm-install' ), 'sqlite-install' ) ); ?>"><?php esc_html_e( 'Install SQLite database', 'sqlite-database-integration' ); ?></a>
+			<?php if ( $override_db_dropin ) : ?>
+				<p>
+					<strong>NOTE:</strong>
+					<?php
+					printf(
+						/* translators: %s: db.php drop-in path */
+						esc_html__( 'We’ve detected an existing database drop-in file at %s, created by the Query Monitor plugin.', 'sqlite-database-integration' ),
+						'<code>' . esc_html( basename( WP_CONTENT_DIR ) ) . '/db.php</code>'
+					);
+					?>
+					<?php esc_html_e( 'To enable SQLite support, this file will need to be replaced.', 'sqlite-database-integration' ); ?>
+					<?php esc_html_e( 'The Query Monitor plugin will continue to function correctly after the change. You can safely proceed with the installation.', 'sqlite-database-integration' ); ?>
+				</p>
 			<?php endif; ?>
+
+			<p><?php esc_html_e( 'By clicking the button below, you will be redirected to the WordPress installation screen to setup your new database', 'sqlite-database-integration' ); ?></p>
+
+			<a class="button button-primary" href="<?php echo esc_url( wp_nonce_url( admin_url( 'admin.php?page=sqlite-integration&confirm-install' ), 'sqlite-install' ) ); ?>"><?php esc_html_e( 'Install SQLite database', 'sqlite-database-integration' ); ?></a>
 		<?php endif; ?>
 	</div>
 	<?php

diff --git a/integrations/query-monitor/boot.php b/integrations/query-monitor/boot.php
@@ -0,0 +1,122 @@
+<?php
+
+/**
+ * Boot Query Monitor from the SQLite Database Integration plugin.
+ *
+ * When the Query Monitor plugin exists in its standard location, let's check
+ * if it is active, so we can boot it eagerly. This is a workaround to avoid
+ * SQLite and Query Monitor competing for the "wp-content/db.php" file.
+ *
+ * This file is a modified version of the original Query Monitor "db.php" file.
+ *
+ * See: https://github.com/johnbillion/query-monitor/blob/develop/wp-content/db.php
+ */
+
+/*
+ * In Playground, the SQLite plugin is preloaded without using the "db.php" file.
+ * To prevent Query Monitor from injecting its own "db.php" file, we need to set
+ * the "QM_DB_SYMLINK" constant to "false".
+ */
+if ( ! defined( 'QM_DB_SYMLINK' ) ) {
+	define( 'QM_DB_SYMLINK', false );
+}
+
+// 1. Check if we should load Query Monitor (as per the original "db.php" file).
+if ( ! defined( 'ABSPATH' ) ) {
+	exit;
+}
+
+if ( ! defined( 'DB_USER' ) ) {
+	return;
+}
+
+if ( defined( 'QM_DISABLED' ) && QM_DISABLED ) {
+	return;
+}
+
+if ( defined( 'WP_INSTALLING' ) && WP_INSTALLING ) {
+	return;
+}
+
+if ( 'cli' === php_sapi_name() && ! defined( 'QM_TESTS' ) ) {
+	return;
+}
+
+if ( defined( 'DOING_CRON' ) && DOING_CRON ) {
+	return;
+}
+
+if ( is_admin() ) {
+	if ( isset( $_GET['action'] ) && 'upgrade-plugin' === $_GET['action'] ) {
+		return;
+	}
+
+	if ( isset( $_POST['action'] ) && 'update-plugin' === $_POST['action'] ) {
+		return;
+	}
+}
+
+// 2. Check if Query Monitor is active.
+if ( null === $wpdb->options ) {
+	global $table_prefix;
+	$wpdb->set_prefix( $table_prefix ?? '' );
+}
+
+$query_monitor_active = false;
+try {
+	$value                = $wpdb->get_row(
+		$wpdb->prepare(
+			"SELECT option_value FROM $wpdb->options WHERE option_name = %s LIMIT 1",
+			'active_plugins'
+		)
+	);
+	$query_monitor_active = in_array(
+		'query-monitor/query-monitor.php',
+		unserialize( $value->option_value ),
+		true
+	);
+} catch ( Throwable $e ) {
+	return;
+}
+
+if ( ! $query_monitor_active ) {
+	return;
+}
+
+// 3. Determine the plugins directory.
+if ( defined( 'WP_PLUGIN_DIR' ) ) {
+	$plugins_dir = WP_PLUGIN_DIR;
+} else {
+	$plugins_dir = WP_CONTENT_DIR . '/plugins';
+}
+
+// 4. Load Query Monitor (as per the original "db.php" file).
+$qm_dir = "{$plugins_dir}/query-monitor";
+$qm_php = "{$qm_dir}/classes/PHP.php";
+
+if ( ! is_readable( $qm_php ) ) {
+	return;
+}
+require_once $qm_php;
+
+if ( ! QM_PHP::version_met() ) {
+	return;
+}
+
+if ( ! file_exists( "{$qm_dir}/vendor/autoload.php" ) ) {
+	add_action( 'all_admin_notices', 'QM_PHP::vendor_nope' );
+	return;
+}
+
+require_once "{$qm_dir}/vendor/autoload.php";
+
+if ( ! class_exists( 'QM_Backtrace' ) ) {
+	return;
+}
+
+if ( ! defined( 'SAVEQUERIES' ) ) {
+	define( 'SAVEQUERIES', true );
+}
+
+// 5. Mark the Query Monitor integration as loaded.
+define( 'SQLITE_QUERY_MONITOR_LOADED', true );
diff --git a/integrations/query-monitor/plugin.php b/integrations/query-monitor/plugin.php
@@ -0,0 +1,89 @@
+<?php // phpcs:disable WordPress.Files.FileName.InvalidClassFileName
+
+if ( ! class_exists( 'QM_Output_Html_DB_Queries' ) || ! class_exists( 'QM_Collectors' ) ) {
+	return;
+}
+
+/**
+ * Override Query Monitor's "QM_Output_Html_DB_Queries" to inject SQLite info.
+ */
+class SQLite_QM_Output_Html_DB_Queries extends QM_Output_Html_DB_Queries {
+	/**
+	 * Override the parent method to inject SQLite info.
+	 *
+	 * Currently, Query Monitor doesn't provide a way to customize the rendered
+	 * query HTML. To overcome this limitation, we capture the HTML generated by
+	 * the parent method and modify it to inject the SQLite query data.
+	 *
+	 * @param array<string, mixed> $row  The row data.
+	 * @param array<int, string>   $cols The column names.
+	 * @return void
+	 */
+	protected function output_query_row( array $row, array $cols ) {
+		// Capture the query row HTML.
+		ob_start();
+		parent::output_query_row( $row, $cols );
+		$data = ob_get_length() > 0 ? ob_get_clean() : '';
+
+		// Get the corresponding SQLite queries.
+		global $wpdb;
+		static $query_index = 0;
+		$sqlite_queries     = $wpdb->queries[ $query_index ]['sqlite_queries'] ?? array();
+		$sqlite_query_count = count( $sqlite_queries );
+		$query_index       += 1;
+
+		// Build the SQLite info HTML.
+		$sqlite_info  = sprintf(
+			'<div class="qm-info" style="margin: 15px 0 8px;">Executed %d SQLite %s:</div>',
+			$sqlite_query_count,
+			1 === $sqlite_query_count ? 'Query' : 'Queries'
+		);
+		$sqlite_info .= '<ol>';
+		foreach ( $sqlite_queries as $query ) {
+			$sqlite_info .= '<li class="qm-sqlite-query" style="list-style: decimal !important; margin-left: 20px !important;">';
+			$sqlite_info .= '<code>' . str_replace( '<br>', '', self::format_sql( $query['sql'] ) ) . '</code>';
+			$sqlite_info .= '</li>';
+		}
+		$sqlite_info .= '</ol>';
+
+		// Inject toggle button and SQLite info into the query row HTML.
+		$toggle_button  = '<button class="qm-toggle sqlite-toggle" data-on="+" data-off="-" aria-expanded="false" aria-label="Toggle SQLite queries" title="Toggle SQLite queries"><span aria-hidden="true">+</span></button>';
+		$toggle_content = sprintf( '<div class="qm-toggled" style="display: none;">%s</div>', $sqlite_info );
+
+		$data = str_replace( 'qm-row-sql', 'qm-row-sql qm-has-toggle', $data );
+		$data = preg_replace(
+			'/(<td class="qm-row-sql.*?">)(.*?)(<\/td>)/s',
+			implode(
+				array(
+					'$1',
+					str_replace( '$', '\\$', $toggle_button ),
+					'$2',
+					str_replace( '$', '\\$', $toggle_content ),
+					'$3',
+				)
+			),
+			$data
+		);
+		echo $data;
+	}
+}
+
+// Remove the default Query Monitor class and replace it with the custom one.
+remove_filter( 'qm/outputter/html', 'register_qm_output_html_db_queries', 20 );
+
+/**
+ * Register the custom HTML output class.
+ *
+ * @param array<string, QM_Output> $output
+ * @param QM_Collectors            $collectors
+ * @return array<string, QM_Output>
+ */
+function register_sqlite_qm_output_html_db_queries( array $output, $collectors ) {
+	$collector = QM_Collectors::get( 'db_queries' );
+	if ( $collector ) {
+		$output['db_queries'] = new SQLite_QM_Output_Html_DB_Queries( $collector );
+	}
+	return $output;
+}
+
+add_filter( 'qm/outputter/html', 'register_sqlite_qm_output_html_db_queries', 20, 2 );