protected function prepare_item_for_database( $request ) {

		$prepared_item = parent::prepare_item_for_database( $request );
		$schema        = $this->get_item_schema();

		// Lesson's audio embed URL.
		if ( ! empty( $schema['properties']['audio_embed'] ) && isset( $request['audio_embed'] ) ) {
			$prepared_item['audio_embed'] = $request['audio_embed'];
		}

		// Lesson's video embed URL.
		if ( ! empty( $schema['properties']['video_embed'] ) && isset( $request['video_embed'] ) ) {
			$prepared_item['video_embed'] = $request['video_embed'];
		}

		// Parent (section) id.
		if ( ! empty( $schema['properties']['parent_id'] ) && isset( $request['parent_id'] ) ) {

			$parent_section_id = absint( $request['parent_id'] );

			// Retrieve the parent section.
			$parent_section = $parent_section_id ? llms_get_post( $parent_section_id ) : null;

			if ( $parent_section && is_a( $parent_section, 'LLMS_Section' ) ) {

				$parent_course = $parent_section->get_course();

				if ( ! current_user_can( 'edit_post', $parent_section_id ) ||
					! $parent_course || ! is_a( $parent_course, 'LLMS_Course' ) ||
					! current_user_can( 'edit_post', $parent_course->get( 'id' ) ) ) {
					return llms_rest_authorization_required_error( __( 'Sorry, you are not allowed to create or move lessons into the requested section.', 'lifterlms' ) );
				}

				$prepared_item['parent_section'] = $parent_section_id;
				$prepared_item['parent_course']  = $parent_course->get( 'id' );

			} else {
				// An empty or invalid parent_id denotes an "orphaned" lesson.
				$prepared_item['parent_section'] = 0;
				$prepared_item['parent_course']  = 0;
			}
		}

		// Course id.
		if ( ! empty( $schema['properties']['course_id'] ) && isset( $request['course_id'] ) ) {

			$parent_course = llms_get_post( $request['course_id'] );

			if ( ! $parent_course || ! is_a( $parent_course, 'LLMS_Course' ) ) {
				return llms_rest_bad_request_error( __( 'Invalid course_id param. It must be a valid Course ID.', 'lifterlms' ) );
			}

			if ( ! current_user_can( 'edit_post', $parent_course->get( 'id' ) ) ) {
				return llms_rest_authorization_required_error( __( 'Sorry, you are not allowed to create or move lessons into the requested course.', 'lifterlms' ) );
			}

			$prepared_item['parent_course'] = $request['course_id'];
		}

		// Order.
		if ( ! empty( $schema['properties']['order'] ) && isset( $request['order'] ) ) {

			// order must be > 0. It's sanitized as absint so it cannot come as negative value.
			if ( 0 === $request['order'] ) {
				return llms_rest_bad_request_error( __( 'Invalid order param. It must be greater than 0.', 'lifterlms' ) );
			}

			$prepared_item['order'] = $request['order'];
		}

		// Public (free lesson).
		if ( ! empty( $schema['properties']['public'] ) && isset( $request['public'] ) ) {
			$prepared_item['free_lesson'] = empty( $request['public'] ) ? 'no' : 'yes';
		}

		// Points.
		if ( ! empty( $schema['properties']['points'] ) && isset( $request['points'] ) ) {
			$prepared_item['points'] = $request['points'];
		}

		// Drip days.
		if ( ! empty( $schema['properties']['drip_days'] ) && isset( $request['drip_days'] ) ) {

			// drip_days must be > 0. It's sanitized as absint so it cannot come as negative value.
			if ( 0 === $request['drip_days'] ) {
				return llms_rest_bad_request_error( __( 'Invalid drip_days param. It must be greater than 0.', 'lifterlms' ) );
			}

			$prepared_item['days_before_available'] = $request['drip_days'];
		}

		// Drip date.
		if ( ! empty( $schema['properties']['drip_date'] ) && isset( $request['drip_date'] ) ) {
			$drip_date = rest_parse_date( $request['drip_date'] );

			// Drip date is nullable.
			if ( empty( $drip_date ) ) {
				$prepared_item['date_available'] = '';
				$prepared_item['time_available'] = '';
			} else {
				$prepared_item['date_available'] = date_i18n( 'Y-m-d', $drip_date );
				$prepared_item['time_available'] = date_i18n( 'H:i:s', $drip_date );
			}
		}

		// Drip method.
		if ( ! empty( $schema['properties']['drip_method'] ) && isset( $request['drip_method'] ) ) {
			$prepared_item['drip_method'] = 'none' === $request['drip_method'] ? '' : $request['drip_method'];
		}

		// Quiz enabled.
		if ( ! empty( $schema['properties']['quiz']['properties']['enabled'] ) && isset( $request['quiz']['enabled'] ) ) {
			$prepared_item['quiz_enabled'] = empty( $request['quiz']['enabled'] ) ? 'no' : 'yes';
		}

		// Quiz id.
		if ( ! empty( $schema['properties']['quiz']['properties']['id'] ) && ! empty( $request['quiz']['id'] ) ) {

			$quiz_id = absint( $request['quiz']['id'] );

			// check if quiz exists.
			$quiz = llms_get_post( $quiz_id );

			if ( is_a( $quiz, 'LLMS_Quiz' ) ) {

				if ( ! current_user_can( 'edit_post', $quiz_id ) ) {
					return llms_rest_authorization_required_error( __( 'Sorry, you are not allowed to attach the requested quiz to this lesson.', 'lifterlms' ) );
				}

				$prepared_item['quiz'] = $quiz_id;
			}
		}

		// Quiz progression.
		if ( ! empty( $schema['properties']['quiz']['properties']['progression'] ) && isset( $request['quiz']['progression'] ) ) {
			$prepared_item['require_passing_grade'] = 'complete' === $request['quiz']['progression'] ? 'no' : 'yes';
		}

		/**
		 * Filters a lesson before it is inserted via the REST API.
		 *
		 * @since 1.0.0-beta.7
		 *
		 * @param array           $prepared_item Array of lesson item properties prepared for database.
		 * @param WP_REST_Request $request       Full details about the request.
		 * @param array           $schema        The item schema.
		 */
		return apply_filters( 'llms_rest_pre_insert_lesson', $prepared_item, $request, $schema );
	}