PHP Notice Trying to get property of non-object

Question

I seem to be receiving a number of php notices advising 'Trying to get property of non-object'.

I assume it is the way I have structured the mysql statement but I am a little unsure and I am after assistance here.

The function is as follows:-

public function getPreviousBlock($iHeight=0) {
    $stmt = $this->mysqli->prepare("
        SELECT height
        FROM " . $this->block->getTableName() . "
        WHERE height < ?
        ORDER BY height DESC
        LIMIT 1");
    if ($this->checkStmt($stmt) && $stmt->bind_param('i', $iHeight) && $stmt->execute() && $result = $stmt->get_result())
        return $result->fetch_object()->height;
    return $this->sqlError();
}

Any help would be much appreciated.

Which line is the error on? Which variable is it trying to get the property from? — Scuzzy, Jan 11 '18 at 02:37
Why do I feel everytime I ask a question on stackoverflow I get the good old 'Possible duplicate' which never helps me. — daygle, Jan 11 '18 at 02:47
What is inside `$result`? Have you checked with `is_object($result)`, if it is really an object? — Geshode, Jan 11 '18 at 02:47

score 1 · Accepted Answer · answered Jan 11 '18 at 04:05

1

fetch_object() will return NULL if there are no more rows in the result set. Of course NULL is not an object so you will get this error.

So you need to check for example:

$obj = $result->fetch_object();
if ($obj) {
   return $obj->height;
} else {
   return null;
}

answered Jan 11 '18 at 04:05

Vũ Nhật Anh

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Thanks for the help :) – daygle Jan 11 '18 at 05:02
Does this look correct?`public function getPreviousBlock($iHeight=0) { $stmt = $this->mysqli->prepare(" SELECT height FROM " . $this->block->getTableName() . " WHERE height < ? ORDER BY height DESC LIMIT 1"); if ($this->checkStmt($stmt) && $stmt->bind_param('i', $iHeight) && $stmt->execute() && $result = $stmt->get_result()) $obj = $result->fetch_object(); if ($obj) { return $obj->height; } else { return null; } return $this->sqlError(); }` – daygle Jan 11 '18 at 05:06
I think it should be like this ```function getPreviousBlock($iHeight = 0) { $stmt = $this->mysqli->prepare(" SELECT height FROM " . $this->block->getTableName() . " WHERE height < ? ORDER BY height DESC LIMIT 1"); if ($this->checkStmt($stmt) && $stmt->bind_param('i', $iHeight) && $stmt->execute() && $result = $stmt->get_result()) { $obj = $result->fetch_object(); if ($obj) { return $obj->height; } else { return null; } } return $this->sqlError(); } ``` – Vũ Nhật Anh Jan 11 '18 at 06:39

PHP Notice Trying to get property of non-object

1 Answers1