How to call mysqli query in a function

Question

I keep getting this error and can't figure out why: "PHP Fatal error: Call to a member function query() on null"

All my mysqli calls work except within a function.

My connection.php file has:

$connection = new mysqli("localhost", "user", "pass", "db");

I've tried setting $connection as a global thinking this was a scope problem, but it's still a thing.

include('connection.php');

function text($x) {
  $query = "SELECT * FROM content WHERE page='". $x ."'";
  $result = $connection->query($query)->fetch_assoc();
  return $result['column'];
}
test('home');

Querying outside of functions works fine.

score 0 · Accepted Answer · answered Jan 30 '19 at 00:00

0

You should declare you variable $connection as global, to use it inside your function:

include('connection.php');

function text($x) {
  global $connection;
  $query = "SELECT * FROM content WHERE page='". $x ."'";
  $result = $connection->query($query)->fetch_assoc();
  return $result['column'];
}
test('home');

answered Jan 30 '19 at 00:00

Ass3mbler

3,539
2
19
17

this is usually bad practice, https://stackoverflow.com/questions/5166087/php-global-in-functions – Jan 30 '19 at 00:12
@Tim, I agree, but I'm answering his question respecting the prototype of his function – Ass3mbler Jan 30 '19 at 00:14
I cant see how answering, with you agree is bad practice, is helpful to the OP – Jan 30 '19 at 00:16
It's easy, because his question is not about good practices, but about how to make his code work while it's not working, and his prototype doesn't have a second parameter. If he want to use a bad practice, he may have his reasons for doing it, like (in example) avoiding to refactor an existing codebase. So if it's possible to answer without forcing such a change, it should be done :) – Ass3mbler Jan 30 '19 at 00:22
1

@tim This answer is redundant, as is the "bad practice" meme. Having *one single* "global" var for the db connection has never killed anyone. – mario Jan 30 '19 at 00:22
the solutions listed in the link i provided make much more sense than this one. calling it a meme is disingenuous, its not as if ther are no alternatives. – Jan 30 '19 at 00:59
What is the best way in this case? Create a new $connection object in the function? – dstana Jan 30 '19 at 01:30

smavroud · Answer 2 · 2019-01-30T11:19:24.060

0

It would be better to pass the $connection variable as parameter.

include('connection.php');

function text($x, $connection) {
  $query = "SELECT * FROM content WHERE page='". $x ."'";
  $result = $connection->query($query)->fetch_assoc();
  return $result['column'];
}
test('home',$connection);

edited Jan 30 '19 at 11:19

answered Jan 30 '19 at 00:01

smavroud

125
4

This doesn't work? – dstana Jan 30 '19 at 01:26

How to call mysqli query in a function

2 Answers2