php函数返回数据库表中的用户列表

Question

I am trying to get the list of all the users in my table in a function then return the list to a php page. I think I am missing some small detail because i can not get anything returned. I am new to OOP and PDO, so I am having trouble pin pointing the problem.

Here is the function

public function get_users() {

    $query = $this->db->prepare("SELECT * FROM `users` ");

    try{
                    $results = array();
        $query->execute();
        while($rows = $query->fetch_assoc())
                {
                    $results[] = $rows;
                }
    }catch(PDOException $e){
        die($e->getMessage());
    }

    return $results;

}   

And in the page:

$user_list  = $users->get_users();
foreach ($user_list as $ul) {
    echo $ul['username'];
}

Any pointers would be a great help. Thank you

Answer 1

Change:

    while($rows = $query->fetch_assoc())
            {
                $results[] = $rows;
            }

to:

    while($rows = $query->fetch(PDO::FETCH_ASSOC))
            {
                $results[] = $rows;
            }

or:

    $results = $query->fetchAll(PDO::FETCH_ASSOC);

There is no fetch_assoc method in PDO, that's mysqli.

Answer 2

First of all, there's no need to prepare that statement. There aren't any bound parameters, so it doesn't make sense (IMHO). You can do it, but since you won't be running the query multiple times there no benefit.

Second of all, you can set \\PDO::FETCH_ASSOC at instantiation or at fetch. Much nicer, again IMHO.

Finally, if you use \\PDOStatment::fetchAll() , you're already returning an array, so no need to build that array.

Your new, simpler function would look like this (untested):

public function get_users()
{
    try {
        return $this->db
            ->query("SELECT * FROM `users`")
            ->fetchAll(\PDO::FETCH_ASSOC);
    } catch (\PDOException $e) {
        die($e->getMessage());
    }
}

Answer 3

you have forgaten to initialize $results as array and return $results not $results[]

public function get_users() {

    $query = $this->db->prepare("SELECT * FROM `users` ");
    $results=array();
    try{
        $query->execute();
        while($rows = $query->fetch_assoc())
                {
                    $results[] = $rows;
                }
    }catch(PDOException $e){
        die($e->getMessage());
    }

    return $results;//correct your return also

}