How do I make sure that values from MySQL keep their type in PHP?

Question

I am having a problem in my PHP script where values called from MySQL are being returned as strings, despite being marked in the database as int and tinyint.

This is a problem because when converting an array based on MySQL date into JSON data, values that should be integers are placed in double quotes, which is causing trouble in both Javascript and iPhone apps that use that JSON data. I am getting JSON values that look like "key" : "1", when what I want is "key" : 1.

After doing some research, it seems that it should be possible to get the values as their native type so long as one has PHP 5.3, and the mysqlnd module installed. I have 5.3.3 and phpinfo() seems to indicate I have the mysqlnd module installed and running:

mysqlnd enabled
Version mysqlnd 5.0.10 - 20111026

However, my values are still being returned as strings.

I have looked at the PHP manual entry for mysqlnd, and it's always possible I'm missing the obvious, but I don't see anything that indicates I need to do anything specific in my code to get the native values.

What exactly do I do to get my MySQL functions in PHP to give me the MySQL results in their native type?

---

In order to fascillitate an answer below, this is the command I use to connect to the database:

private function databaseConnect()
{
    $this->mysqli = new mysqli(Database::$DB_SERVER, Database::$DB_USERNAME, Database::$DB_PASSWORD);
    $this->mysqli->set_charset("utf8");
    return true;
}

private function dbConnect()
{
    Database::$USE_MYSQLI = extension_loaded('mysqli');
    if (!$this->databaseConnect())
    {
        echo "Cannot Connect To The Database Server";
        throw new Exception();
    }
    if (!$this->databaseSelectDB())
    {
        echo "The database server connected, but the system could not find the right database";
        throw new Exception();
    }
}

private function databaseQuery($query)
{
    return $this->mysqli->query($query);
}

public function doQuery($query)
{
    $result = $this->databaseQuery($query);
    if ($result == FALSE)
    {
        //ErrorHandler::backtrace();
        die("This query did not work: $query");
    }
    return $result;
}

private function getRows($table, $matches, $orderBy = array(), $limit = array())
{
    $calcFoundRows = '';
    if (count($limit) > 0)
    {
        $calcFoundRows = ' SQL_CALC_FOUND_ROWS';
    }
    $query = 'SELECT ' . $calcFoundRows . ' * FROM ' . $table;
    if (count($matches) > 0)
    {
        $query .= ' WHERE ';
        $keys = array_keys($matches);
        $first = true;
        foreach ($keys as $key)
        {
            if (!$first)
            {
                $query .= ' AND ';
            }
            $first = false;

            // now he is safe to add to the query
            // the only time this is an array is when this is called by getSelectedUsers or getSelectedArticles
            // in that case it is an array of array's as the key (which is the column name) may have more than
            // one condition
            if (is_array($matches[$key]))
            {
                $firstForColumn = true;
                foreach ($matches[$key] as $conditions)
                {
                    if (!$firstForColumn)
                    {
                        $query .= ' AND ';
                    }
                    $firstForColumn = false;

                    // if the value is an array we generate an OR selection
                    if (is_array($conditions[1]))
                    {
                        $firstOr = true;
                        $query .= '(';

                        foreach ($conditions[1] as $value)
                        {
                            if (!$firstOr)
                            {
                                $query .= ' OR ';
                            }
                            $firstOr = false;
                            // clean this guy before putting him into the query
                            $this->cleanMySQLData($value);
                            if ($conditions[0] == Selection::$CONTAINS)
                            {
                                //$query .= 'MATCH (' . $key . ') AGAINST (' . $value . ') ';
                                $value = trim($value, "'");
                                $value = "'%" . $value . "%'";
                                $query .= $key . ' LIKE ' . $value;
                            }
                            else
                            {
                                $query .= $key . ' ' . $conditions[0] . ' ' . $value;
                            }
                        }

                        $query .= ')';
                    }
                    else
                    {
                        // clean this guy before putting him into the query
                        $var = $conditions[1];
                        $this->cleanMySQLData($var);
                        if ($conditions[0] == Selection::$CONTAINS)
                        {
                            //$query .= 'MATCH (' . $key . ') AGAINST (' . $var . ') ';
                            $var = trim($var, "'");
                            $var = "'%" . $var . "%'";
                            $query .= $key . ' LIKE ' . $var;
                        }
                        else
                        {
                            $query .= $key . ' ' . $conditions[0] . ' ' . $var;
                        }
                    }
                }
            }
            else
            {
                // clean this guy before putting him into the query
                $this->cleanMySQLData($matches[$key]);
                $query .= $key . " = " . $matches[$key];
            }
        }
    }
    if (count($orderBy) > 0)
    {
        $query .= " ORDER BY ";
        $first = true;
        foreach ($orderBy as $orderCol)
        {
            if (!$first)
            {
                $query .= ',';
            }
            $query .= $orderCol;
            $first = false;
        }
    }

    if (count($limit) > 0)
    {
        $query .= ' LIMIT ' . $limit[0];
        if (count($limit) > 1)
        {
            $query .= ',' . $limit[1];
        }
    }


    $result = $this->doQuery($query);
    $data = array();
    while ($row = $this->databaseFetchAssoc($result))
    {
        $data[] = $row;
    }
    if (strlen($calcFoundRows) > 0)
    {
        $numRows = $this->databaseCountFoundRows();
        $key = '^^' . $table . '_selectionCount';
        Session::getSession()->putUserSubstitution($key, $numRows);
    }

    return $data;
}

Answer 1

What exactly do I do to get my MySQL functions in PHP to give me the MySQL results in their native type?

You connect to the database, then you prepare your query, execute it, bind the result and then you fetch it.

Let's do these steps line-by-line:

$conn = new Mysqli('localhost', 'testuser', 'test', 'test');
$stmt = $conn->prepare("SELECT id FROM config LIMIT 1");
$stmt->execute();
$stmt->bind_result($id);
$stmt->fetch();
var_dump($id); # it's an int!

This works for me. As you wrote your code is more complex, you will need to locate the place where you query the database. Check that you're using Mysqli::prepare() and if not, introduce it.

You will also need to use Mysqli_Stmt::execute() and then Mysqli_Stmt::bind_result() otherwise the (here integer) type is not preserved for that result column.

Answer 2

However, my values are still being returned as strings.

You are in PHP, where it does not matter that your data are int, bool, strings... if they have such a type they are called scalar data and dynamic castings will allow you to make them behave as you want. For example, the string "12345"+"54321" will give you 66666. If you absolutely want your data to be of a particular type, as in every language, it is not the driver's job. In Java you've got something like .getString, .getInt methods in JDBC's interfaces, in PHP you do not have as it is not very useful. You will have to cast yourself your data with intval boolval strval... functions or (int), (bool)... casting operators.

As your post said you can have it by using server-side prepared statement:

Advantages of using mysqlnd for PDO

mysqlnd returns native data types when using Server-side Prepared Statements, for example an INT column is returned as an integer variable not as a string. That means fewer data conversions internally.

With PDO

You have to put this line after your connection

$PDO->setAttribute(PDO::ATTR_EMULATE_PREPARES,false);

then, when you want to query :

$s = $PDO->prepare('yourquery');
//here, binding params
$s->bindValue('paramName','paramValue');
$s->execute();

With Mysqli

As you use mysqli, the syntax will be a little different : Note: there is no way of client-side prepared statement so you won't need the configuration line that I put with PDO.

So your query will look like that:

$statement = $MySQli->prepare('your query');
$statement->bind_param('si', $stringParam, $intParam);
$statement->bind_result($var1, $var2 /*,...*/);
$statement->execute();
while($statement->fetch()){
  //process here, result will be in var1, var2...
}

You can see that, here, there is no built-in fetchAll method. To bind your data you need to use variables as it is not passed as value like in PDOStatement::bindValue() but by reference. Moreover the types are defined in the first arg (s for string, i for integer...) There are no named parameters only indexed ones. The fetch method works in a different way and needs you to call bind_result BEFORE the execute statement;