Using class/object attribute in mysql query with php

Question

im creating a simple php user system, i have a user class and i`m storing the new user values using this function (the Add) inside user class:

    private function NewUser($nome, $email, $tel, $cidade, $estado, $aniversario) {
    $this -> name = mysql_real_escape_string($nome);
    $this -> email = mysql_real_escape_string($email);
    $this -> telefone = mysql_real_escape_string($tel);
    $this -> cidade = mysql_real_escape_string($cidade);
    $this -> estado = mysql_real_escape_string($estado);
    $this -> dia = substr($aniversario, 0, 2);
    $this -> mes = substr($aniversario, 3, 2);
    $this -> ano = substr($aniversario, 6);

    }

    public function Add($nome, $email, $tel, $cidade, $estado, $aniversario) {
    $this -> NewUser($nome, $email, $tel, $cidade, $estado, $aniversario);
    $Create_query = "INSERT INTO user (nome, email, telefone, cidade,    estado,      dia, mes, ano) VALUES ('{$this -> name}', '{$this -> email}',
    '{$this -> telefone}', '{$this -> cidade}', '{$this -> estado}', '{$this -     > dia}', '{$this -> mes}', '{$this -> ano}')";
    $query_user = connectdb::sql_query($Create_query); // my connect class
    if ($query_user) {
        $answer = array('done' => 'done');
        echo json_encode($answer);
    }
    else {
        validate::returnError();
    }
     }

If i try to run the insert with $this -> attribute or '$this -> attribute' i got a Object of class User could not be converted to string error,but if i run then as '{$this -> attribute}'it works. I have found these {} method, in a stack overflow answer, but theres no detail`s, can someone explain why this work, and if its safe/correctly? Thank you for your time.

Do you still get the error when you remove the spaces before and after ` -> ` everywhere in your code? E.g. $this -> name would become $this->name, and likewise everywhere else in your code. — Tomas Creemers
– Tomas Creemers, Commented Oct 26, 2013 at 23:24

puelo · Accepted Answer · 2013-10-26 23:32:31Z

1

To answer your question about the curly braces: Curly braces are used to explicitly specify the end of a variable name.

Some examples can be seen here: http://docs.php.net/manual/en/language.variables.variable.php

As for the error (Object of class User...): The problem there are the whitespaces in $this -> attribute. Since you are using them inside of a string the whitespaces are getting interpreted as what they are, whitespaces. So it tries to convert just $this to a string, which is not possible (see the error). If you use the the curly braces php knows exactly when the variable starts and when it ends.

On another note: try to use PDO instead of simple mysql_query...Have a look here: http://php.net/manual/de/book.pdo.php

answered Oct 26, 2013 at 23:32

puelo

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