Building the Model

<?php
class File_manager_model extends Model {

    private string $table_name = 'file_manager';

    public function get_all_files(
        int $limit,
        int $offset,
        string $search_query = '',
        string $search_column = ''
    ): array {

        $where_clause = '';

        if ($search_query !== '') {
            $col = ($search_column !== '')
                ? $search_column
                : 'doc_name';
            $where_clause = 'WHERE ' . $col
                          . ' LIKE :search_query';
        }

        $sql = 'SELECT id, doc_name, file_name,
                       file_size, file_type
                FROM ' . $this->table_name . '
                ' . $where_clause . '
                ORDER BY id DESC
                LIMIT :limit OFFSET :offset';

        $params = [
            ':limit' => (int) $limit,
            ':offset' => (int) $offset
        ];

        if ($search_query !== '') {
            $params[':search_query']
                = '%' . $search_query . '%';
        }

        return $this->db->query(
            $sql, 'object', $params
        );
    }

    public function count_all_files(
        string $search_query = '',
        string $search_column = ''
    ): int {

        $where_clause = '';

        if ($search_query !== '') {
            $col = ($search_column !== '')
                ? $search_column
                : 'doc_name';
            $where_clause = 'WHERE ' . $col
                          . ' LIKE :search_query';
        }

        $sql = 'SELECT COUNT(*) as count
                FROM ' . $this->table_name . '
                ' . $where_clause;

        $params = [];

        if ($search_query !== '') {
            $params[':search_query']
                = '%' . $search_query . '%';
        }

        $result = $this->db->query(
            $sql, 'object', $params
        );

        return (int) ($result[0]->count ?? 0);
    }

    public function get_file_by_id(
        int $update_id
    ): array|false {

        $record_obj = $this->db->get_where(
            $update_id, $this->table_name
        );

        if ($record_obj === false) {
            return false;
        }

        return [
            'id' => (int) $record_obj->id,
            'doc_name' => $record_obj->doc_name,
            'file_name' => $record_obj->file_name,
            'file_path' => $record_obj->file_path,
            'file_size' => (int) $record_obj->file_size,
            'file_type' => $record_obj->file_type
        ];
    }

    public function insert_file(array $data): int {
        return $this->db->insert(
            $data, $this->table_name
        );
    }

    public function delete_file(int $update_id): void {
        $this->db->delete(
            $update_id, $this->table_name
        );
    }

}