Laravel Custom Exception Handlers

laravel

Laravel throws a large number of exceptions and is very easy to customize them to suit our needs as required.

Note: These exceptions are most helpful if you’re building an API.

The code for common exception handler lies in the {project_root}/app/Exceptions/ folder, named Handler.php. The default file looks like this in Laravel 5.7.

<?php

namespace App\Exceptions;

use Exception;
use Illuminate\Foundation\Exceptions\Handler as ExceptionHandler;

class Handler extends ExceptionHandler
{
    /**
     * A list of the exception types that are not reported.
     *
     * @var array
     */
    protected $dontReport = [
        //
    ];

    /**
     * A list of the inputs that are never flashed for validation exceptions.
     *
     * @var array
     */
    protected $dontFlash = [
        'password',
        'password_confirmation',
    ];

    /**
     * Report or log an exception.
     *
     * @param  \Exception  $exception
     * @return void
     */
    public function report(Exception $exception)
    {
        parent::report($exception);
    }

    /**
     * Render an exception into an HTTP response.
     *
     * @param  \Illuminate\Http\Request  $request
     * @param  \Exception  $exception
     * @return \Illuminate\Http\Response
     */
    public function render($request, Exception $exception)
    {
        return parent::render($request, $exception);
    }
}

Some of the common exceptions that we’re going to handle in this tutorial are AuthenticationException, MethodNotAllowedHttpException, ModelNotFoundException, NotAcceptableHttpException, NotFoundHttpException, PostTooLargeException, ValidationException.

Below is the explanation for each variable, functions and handler implemented.

protected $dontReport = [] is the array of exceptions that Laravel wouldn’t report. Here we’re going to mention the exceptions that we don’t want laravel to report.

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Customizing Laravel validation JSON message format

laravel request validation customize error message format

By default laravel gives a good enough JSON format for validation errors but what if you want to customize it?

#Original JSON format
{
    "message": "The given data was invalid.",
    "errors": {
        "email": [
            "Please enter email address."
        ],
        "password": [
            "Please enter password."
        ]
    }
}

But for this particular project I decided to change the format to this.

{
    "success": false,
    "success_code": 400,
    "message": "Please enter email address.",
    "errors": [
        {
            "field": "email",
            "message": "Please enter email address."
        },
        {
            "field": "password",
            "message": "Please enter password."
        }
    ]
}

To achieve this I created a ValidationException handler function in app/Exceptions/Handler.php which helped me catch all the exceptions raised as a result of failed validations.

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Time killer and addictive Google Games

We’ve all at least once played the T-rex game on Google Chrome when the internet was done. But do you know Google offers more such games? Of course, these others require a working internet. .

1. 30th Anniversary of PAC-MAN
Google came out with one of the most addictive classic Pac-man game doodle on it’s 30th Anniversary on May 21, 2010. Go ahead and give it a try.

2. Basketball 2012
If you’re into basket ball, this one is definitely for you.

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AngularJS: Prevent form submission or stop page refresh on submit

I have recently started learning AngularJS and came across form that would refresh every time I click the submit button. So, here are a couple of ways to prevent that from happening.

HTML Form

<div ng-app="my-app">
  <div ng-controller="myFormController">
    <form action="test_submit.php" method="post" accept-charset="utf-8" name="myTestForm" ng-submit="myTestForm.$valid && submit()" novalidate>
      <div>
        <label for="fname">First Name</label>
        <input type="text" ng-model="dataForm.fname" name="fname" id="fname" required>
      </div>

      <div>
        <label for="lname">Last Name</label>
        <input type="text" ng-model="dataForm.lname" name="lname" id="lname" required>
      </div>

      <div>
        <label for="email">Email</label>
        <input type="text" ng-model="dataForm.email" name="email" id="email" required>
      </div>

      <div>
        <button name="submit" ng-disabled="myTestForm.$invalid" type="submit">Submit</button>
      </div>
    </form>
  </div>
</div>

Angular JS

var myApp = angular.module('my-app', []);

myApp.controller('myFormController', function($scope, $http) {
  $scope.dataForm = {};

  $scope.submit = function() {
    // Ajax
  };
});

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Gauss Elimination method in C language using Lower triangular matrix

This is a simple C language program that calculates solution of n-linear equations using Non-pivotal Gauss Elimination method. It uses lower triangular matrix to do so, for upper triangular matrix visit here.

#include<stdio.h>
#include<conio.h>
 
float matrix[10][10], m, temp[10];
int i, j, k, n;
 
void lower_traingularisation() {
    for (i=n-1; i>0; i--)
        for (j=i-1; j>=0; j--) {
            m	= matrix[j][i]/matrix[i][i];
            for (k=0; k<n+1; k++) {
                matrix[j][k]	= matrix[j][k]-(m*matrix[i][k]);
            }
        }
} //lower_traingularisation
 
void back_subsitution() {
    for (i=0; i<n; i++) {
        m	= matrix[i][n];
        for (j=0; j<i; j++)
            m	= m - temp[j] * matrix[i][j];
        temp[i]	= m/matrix[i][i];
        printf("\n x%d => %f", i+1, temp[i]);
    }
} // back_subsitution
 
void main() {
    printf("Enter number. of variables :: ");
    scanf("%d", &n);
 
    printf("Enter the augmented matrix: \n");
    for (i=0; i<n; i++)
        for (j=0; j<n+1; j++)
            scanf("%f", &matrix[i][j]);
 
    lower_traingularisation();
 
    printf("The lower traingular matrix is : \n");
 
    for (i=0; i<n; i++) {
        for (j=0; j<n+1; j++)
            printf("%f \t", matrix[i][j]);
        printf("\n");
    }
 
    printf("The required result is : \n");
 
    back_subsitution();
 
    getch();
} // main