Handling undefined variables in laravel

Handling undefined variables in your laravel code is critically important because it can help prevent errors and improve the stability of your program.
Undefined or null variables occur when you try to access a variable that has not been declared or assigned a value.
If you try to use an undefined variable in your code, it can cause errors that can break your program or produce incorrect results.

By handling undefined variables correctly in your laravel project, you can ensure that your program runs smoothly and produces the desired results in production.
There are several ways to handle undefined variables, such as checking for their existence before using them, setting default values,
 using type coercion, or using try-catch blocks to handle errors.
 
the try catch is a great way to achieve error handling. its better to wrap  your controller route connected methods with try-catch block. but when a handling small variable
the try catch block not always great. here some examples that can handle undefined or null variables.

 

in blade files 

Use an isset() check: You can use the isset() function to check if a variable is defined before using it.

 
@if (isset($variable))
    {{ $variable }}
@endif 

Use the @isset directive: Laravel provides a blade directive called @isset that allows you to check if a variable is defined and display its value 

 

 
@isset($variable)
    {{ $variable }}
@endisset 

Use the @unless directive: You can use the @unless directive to check if a variable is not defined and display a default value.

 
@unless (isset($variable))
    Default value
@endunless

 

Use a default value: You can use the or operator to specify a default value for the variable if it is not defined.

 
{{ $variable ?? 'Default value' }}

in code:

 

Use the optional helper function: Laravel provides a helper function called optional() that allows you to specify a default value for the variable if it is not defined.

 
optional($variable, 'Default value');

 

Use a ternary operator: You can use a ternary operator to check if a variable is defined and display its value, or a default value if it is not defined.

 
{{ isset($variable) ? $variable : 'Default value' }}

 

Use the data_get helper function: You can use the data_get() helper function to get a value from an array or object, and specify a default value if the value is not found(i mostly using this)

 
$newval = data_get($arrayOrObject, 'key', 'Default value');

null safe operator (php v7.4 +)

 
$newVal = $object?->keyname;

using 'when' helper The when method invokes the given closure if a given condition is true. The closure will receive the fluent string instance

 
use Illuminate\Support\Str;
 
$string = Str::of('some text:')
                ->when(($yourCondtion == true ), function ($string) {
                    return $string->append('here another part for some text');
});

The "whenContains" method invokes the given closure if the string contains the given value. The closure will receive the fluent string instance

 

use Illuminate\Support\Str;
 
$string = Str::of('your text')
            ->whenContains('text', function ($string) {
                return $string->title();
});

there are few more usefull methods with "when" related checkout out the offcial document page for it. 

https://laravel.com/docs/9.x/helpers#method-fluent-str-when 

 

Use the data_fill helper function: You can use the data_fill helper function to fill in missing values in an array or object with default values.The data_fill function sets a missing value within a nested array or object using "dot" notation:

 
$data = ['products' => ['desk' => ['price' => 100]]];
 
data_fill($data, 'products.desk.price', 200);
 
// ['products' => ['desk' => ['price' => 100]]]
 
data_fill($data, 'products.desk.discount', 10);
 
// ['products' => ['desk' => ['price' => 100, 'discount' => 10]]]

https://laravel.com/docs/9.x/helpers#method-data-fill