Laravel 5 firstOrCreate keep create even set unique to the field - php

Question

Below is my app\Cart.php
use Illuminate\Database\Eloquent\Model;
use Illuminate\Database\Eloquent\SoftDeletes;
class Cart extends Model {
use SoftDeletes;
protected $table = 'cart';
protected $fillable = ['sess','uid'];
}
Below is my app\Http\Controllers\CartController.php
public function cart($id=0, $act, Request $request)
{
$sessId = Session::getId();
switch($act){
case 'Add':
$quantity = $request->only('p_quantity');
$data = $request->except('p_quantity');
$cartId = Cart::firstOrCreate(['sess' => $sessId,'status' => 1]);
break;
case 'Delete':
break;
}
return response()->json(['success' => true,'message' => 'Success', 'act' => $act, 'id' => $id ,'data' => $data, 'quantity'=> $quantity, 'cart'=>$cartId->id]);
}
What i want is check database if the session key exist in table cart.sess, else create new one and get the id.
Question is , when it keep create new duplicate session to database.
may i know where i did wrong?
Thanks
UPDATE [2015-05-27 16:02]:
After i TRUNCATE table and set the sess field to Unique , first submit it look ok, when second submit it show error below:
UPDATE [2015-05-27 16:16]
Code that i use to create database:
CREATE TABLE IF NOT EXISTS `cart` (
`id` int(11) NOT NULL,
`uid` int(11) DEFAULT NULL,
`sess` varchar(40) NOT NULL,
`status` int(11) DEFAULT '1',
`created_at` timestamp NOT NULL DEFAULT '0000-00-00 00:00:00',
`updated_at` timestamp NOT NULL DEFAULT '0000-00-00 00:00:00',
`deleted_at` timestamp NOT NULL DEFAULT '0000-00-00 00:00:00'
) ENGINE=InnoDB AUTO_INCREMENT=7 DEFAULT CHARSET=utf8;

Answer 1

In your database schema, where you created this cart table, the sess column should be unique, but it is not. You should alter it, to be unique:
$table->unique('sess');
Don't forget to delete all records before that, otherwise you will get an error.
EDIT After you posted your table schema I found the problem
sess varchar(40) NOT NULL
You must set the length of sess to at elast 255 characters or the size of your session id, because your session id is longer than 40 symbols. Laravel tries to find a string with 64 characters (or with the length of your session id) for example:
8a9f119eaea027def7268d12e4e4d680
but did not, so it tries to insert new one. Since your column is with length 40, the sess id got truncated to 40 symbols:
8a9f119eaea
and in the next check it would not match, because it is searching for 8a9f119eaea027def7268d12e4e4d680 but in your database you got 8a9f119eaea.

Answer 2

I Solved the problem.
Where
Because in my modal i using SoftDeletes;
How To Solved
it cant has default value inside this field,
but i set it to Default 0000-00-00 00:00:00 , just put it as null by default.
CREATE TABLE IF NOT EXISTS `cart` (
`id` int(11) NOT NULL,
`uid` int(11) DEFAULT NULL,
`sess` varchar(40) NOT NULL,
`status` int(11) DEFAULT '1',
`created_at` timestamp NOT NULL DEFAULT '0000-00-00 00:00:00',
`updated_at` timestamp NOT NULL DEFAULT '0000-00-00 00:00:00',
deleted_at timestamp NOT NULL DEFAULT '0000-00-00 00:00:00'
) ENGINE=InnoDB AUTO_INCREMENT=7 DEFAULT CHARSET=utf8;
to
deleted_at timestamp
Why
firstOrCreate did this query (Check Image Below)
Plugin Above is : https://github.com/barryvdh/laravel-debugbar for who need it.
Thanks