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
– mario, Commented May 20, 2015 at 3:06
You are doing a double wrap so its going to be con->con. You should rethink your structure. Imo — S.Visser
– S.Visser, Commented May 20, 2015 at 3:07
@mario Okay now the error is gone but it is not added on my database. — Keannu Alforque Atilano
– Keannu Alforque Atilano, Commented May 20, 2015 at 3:14
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
– Funk Forty Niner, Commented May 20, 2015 at 3:15

Community · Accepted Answer · 2017-05-23 11:58:09Z

4

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.

edited May 23, 2017 at 11:58

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answered May 20, 2015 at 3:50

Funk Forty Niner

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Comments

Yasitha · Accepted Answer · 2015-05-20 03:18:21Z

-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, 2015 at 3:18

answered May 20, 2015 at 3:16

Yasitha

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9 Comments

Funk Forty Niner Over a year ago

this will still cause a syntax error during the insert value($name)

Funk Forty Niner Over a year ago

Look $Helpers->register("Keannu"); <= it's a "string" ^

Keannu Alforque Atilano Over a year ago

Should it not be a string? what data type should i use ?

someOne Over a year ago

@Fred-ii- Maybe you should provide your kind help as an answer, and the OP should accept :)

Keannu Alforque Atilano Over a year ago

@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.

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