PHP OOP Cannot Query mysqli

Question

I have been struggling for days to figure how to follow OOP in the following procedure.

Here is my connection class which handles my connection to the database.

<?php
class Connection{
    public $con = null;
    public function __construct(){
        return $this->con = new mysqli("127.0.0.1:3306", "root", "root", "tester");
    }

}
?>

And here is my Helpers Class, this class contains all the common methods that will be used in my webapp like Insert data , delete and update.

<?php 
class Helpers{
    public $con = null;
    public function __construct($connection){
        $this->con = $connection;
    }

    public function register($name){
        $con = $this->con;
        $sql = "insert into name(Name)value($name);";
        $con->query($sql);
    }
}
?>

Now I call them like this in my register.php

<?php
require "Connection.php";
require "Helpers.php";

$connection = new Connection();
$Helpers = new Helpers($connection);

$Helpers->register("Keannu");
?>

But I am getting the following error:

Call to undefined method Connection::query().

What did I do wrong?

Since you're wrapping it twice, you'll have to use `$this->con->con->query()` then. Avoid the extra wrapper. And investigate PDO instead of mysqli. That's going to be less effort in the end (in particular for simpler parameter binding). — mario, May 20 '15 at 03:06
You are doing a double wrap so its going to be `con->con`. You should rethink your structure. Imo — S.Visser, May 20 '15 at 03:07
@mario Okay now the error is gone but it is not added on my database. — Keannu Alforque Atilano, May 20 '15 at 03:14
check for errors. the syntax error is clear in the value; it's a string. checking for errors is part of coding/debugging, which you're not doing — Funk Forty Niner, May 20 '15 at 03:15
can one you guys give me a sample code like mine but in the correct way? . Because i'm kinda confused. :) — Keannu Alforque Atilano, May 20 '15 at 03:19
http://php.net/manual/en/mysqli.error.php use that on the query — Funk Forty Niner, May 20 '15 at 03:20
@Fred-ii- Still no good .... can you provide a code like mine but in the correct way? cause i'm confused of everything right now :( . — Keannu Alforque Atilano, May 20 '15 at 03:32
see the guy's answer below, which unfortunately, still contains a syntax error but they're not listening to me, or have left for the day. — Funk Forty Niner, May 20 '15 at 03:34
@Fred -ii- Yea i noticed that. what should be the data type? i was thinking a string because my data type on my db is varchar. — Keannu Alforque Atilano, May 20 '15 at 03:40
`varchar` is correct but the answer below failed to point out about the [string literals](https://dev.mysql.com/doc/refman/5.0/en/string-literals.html) from the get go, nor have they mentioned anything about checking for errors. incomplete answer far as I'm concerned. — Funk Forty Niner, May 20 '15 at 03:42

score 4 · Accepted Answer · edited May 23 '17 at 11:58

In addition to the already given answer, strings in values need to be wrapped in quotes.

I.e.: value ('$name');"; or value ('".$name."');"; which is another method.

Sidenote: value and values are accepted and are both considered as valid syntax in MySQL.

As per the manual: http://dev.mysql.com/doc/refman/5.6/en/insert.html

INSERT [LOW_PRIORITY | DELAYED | HIGH_PRIORITY] [IGNORE]
    [INTO] tbl_name
    [PARTITION (partition_name,...)] 
    [(col_name,...)]
    {VALUES | VALUE} ({expr | DEFAULT},...),(...),...

For more information on string literals, visit
https://dev.mysql.com/doc/refman/5.0/en/string-literals.html
Checking for errors in the query also would have signaled the syntax error.
http://php.net/manual/en/mysqli.error.php

Sidenote: Your present code is open to SQL injection. Use mysqli with prepared statements, or PDO with prepared statements, they're much safer.

Yasitha · Answer 2 · 2015-05-20T03:18:21.780

-1

Change your class as follows. Since you are passing a Connection Object you need to set its con property to the $this->con.

<?php 
class Helpers{
    public $con = null;
    public function __construct($connection){
        $this->con = $connection->con;
    }

    public function register($name){
        $con = $this->con;
        $sql = "insert into name (Name) values ($name);";
        $con->query($sql);
    }
}

edited May 20 '15 at 03:18

answered May 20 '15 at 03:16

Yasitha

2,233
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this will still cause a syntax error during the insert `value($name)` – Funk Forty Niner May 20 '15 at 03:17
Look `$Helpers->register("Keannu");` <= it's a "string" ^ – Funk Forty Niner May 20 '15 at 03:33
Should it not be a string? what data type should i use ? – Keannu Alforque Atilano May 20 '15 at 03:35
@KeannuAlforqueAtilano A string should be fine to use it needs to be encapsulated in quotes though so this answer has an error. It should be `$sql = "insert into name (Name) values ('$name');";`. – chris85 May 20 '15 at 03:39
@chris85 true, but Yasitha should have been the one to point that out and have been told about it. They probably left or are ignoring the comments or don't know how [string literals](https://dev.mysql.com/doc/refman/5.0/en/string-literals.html) work. – Funk Forty Niner May 20 '15 at 03:40
Okay it works now guys! THANK YOU VERY MUCH FOR THE HELP ! :D P.S im new in this site xD sorry for the annoyance. – Keannu Alforque Atilano May 20 '15 at 03:46
@KeannuAlforqueAtilano great and you're welcome, however I sure hope you're not going to accept it; not in its present form anyway. I wouldn't. Not till they fix the syntax error. – Funk Forty Niner May 20 '15 at 03:46
1

@Fred-ii- Maybe you should provide your kind help as an answer, and the OP should accept :) – someOne May 20 '15 at 03:48
1

@Fred-ii- yes fred i'm gonna recode it now i know the concept . the double wrap and the string literals .Thank you very much guys, saved me from days of struggle. – Keannu Alforque Atilano May 20 '15 at 03:51

PHP OOP Cannot Query mysqli

2 Answers2