Call to a member function fetchAll() on a non-object

Question

I do not know why it returns the Call to a member function fetchAll() on a non-object error because I am using the fetchAll method on the _sth object.

Does anybody know why it does this?

FormValidator PHP

$users = $this->_db->query("SELECT * FROM $ruleValue WHERE $input = ?", array($inputValue));
if($users->count()) {
    $this->addError($input, $rule);
}

Method

public function query($sql, $params = array()) {
    $this->_sth = $this->_dbh->prepare($sql);

    if($this->_sth = $this->_sth->execute($params)) {
        return $this->_sth->fetchAll(PDO::FETCH_OBJ);
    }

    return false;
}

[**And again you're trying to use your erroneous function**](http://stackoverflow.com/questions/23200937/pdo-query-method-with-bindvalue-seems-not-to-be-working), with same outcome. — Your Common Sense, Apr 21 '14 at 18:09
Only why I am using it on a function is so that I don't have to repeat the same code over and over. — Kid Diamond, Apr 21 '14 at 18:10
`execute()` returns a boolean. It doesn't have a `fetchAll()` function. Just do `if($this->_sth->execute($params)) {`. — gen_Eric, Apr 21 '14 at 18:11
there is not much code to repeat but there is a HUGE hole in security. you should **get rid of ALL the variables** in the query — Your Common Sense, Apr 21 '14 at 18:11
this time you almost nailed the function, I have to admit. And only query here goes to be unsafe. You should never use a single variable in the query — Your Common Sense, Apr 21 '14 at 18:24

score 3 · Accepted Answer · answered Apr 21 '14 at 18:18

if($this->_sth = $this->_sth->execute($params)) {

The single = is an assignment operator. execute() returns a boolean TRUE or FALSE, and you're assigning that to $this->_sth.

    return $this->_sth->fetchAll(PDO::FETCH_OBJ);

Neither TRUE nor FALSE is an object, and has no fetchAll() method.

The comment from @RocketHazmat is correct, you can test the return value of execute() without assigning it to _sth. Example:

if($this->_sth->execute($params)) {
    return $this->_sth->fetchAll(PDO::FETCH_OBJ);
}

score 1 · Answer 2 · answered Apr 21 '14 at 18:19

As I said already, there are two HUGE flaws.

DO NOT introduce state in your class. Use local variables and return the result.
Ther should be not a single variable in the query ever.

DO NOT introduce state in

public function query($sql, $params = array()) {
    $sth = $this->_dbh->prepare($sql);
    $sth->execute($params);
    return $sth->fetchAll(PDO::FETCH_OBJ);
}

is ALL you need.

Don't be lazy, write full query.

$user = $this->_db->query("SELECT * FROM users WHERE param = ?", [$inputValue]);
if($user) {
    $this->addError($input, $rule);
}

Call to a member function fetchAll() on a non-object

2 Answers2