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How to handle Undefined Offset in laravel?

Posted by: admin October 29, 2017 Leave a comment

Questions:

I am getting this error when I land on the page after logging in:

ErrorException in compiled.php line 11573: Undefined offset: 0 (View:
C:\xampp\htdocs\campusguru\resources\views\home.blade.php)

I know that the cause of this error is the empty variable that I passed to the view.

I have already tried:

if(isset($blog)) { do something }

and in blade view as:

{{ $blogs[0]->title or '' }}

Is there anyway I could handle this error. Or is there a better way of doing it?

Answers:

try the following:

{{ isset($blogs[0]) ? $blogs[0]->title : '' }}

If your using a foreach to get every $blog->title use

@foreach ($blogs as $blog)
  {{ $blog->title }}
@endforeach

Questions:
Answers:

The problem is that $blogs is actually defined and its value is [] (i.e. empty array) so it means that isset($blogs) statement will evaluate to true. Same thing is valid for collections. If a collection is empty (i.e. has no elements but it’s defined) isset($blogs) will still evaluate to true but accessing $blogs[0] will cause an Undefined offset: 0 error.

You could try the following solutions:

Using count

if(count($blogs)) { /* do something */ }

if $blogs = [] or $blogs = null the function count will return zero so that means that $blogs is empty.

Using empty

if(!empty($blogs)) { /* do something */ }

This is the equivalent of writing !isset($var) || $var == false as described in the PHP Manual – empty:

Returns FALSE if var exists and has a non-empty, non-zero
value. Otherwise returns TRUE.

The following things are considered to be empty:

  • "" (an
    empty string)
  • 0 (0 as an integer)
  • 0.0 (0 as a
    float)
  • "0" (0 as a string)
  • NULL
  • FALSE
  • array() (an empty array)
  • $var; (a
    variable declared, but without a value)
  • Checking if a collection is empty

    If $blogs is a Collection is sufficient to check if it is not empty using `isNotEmpty() method:

    @if($blogs->isNotEmpty()) <!-- Do your stuff --> @endif
    

    EDIT

    I forgot to add the blade syntax:

    @if(count($blogs)) <!-- Do whatever you like --> @endif
    

    or

    @if(!empty($blogs)) <!-- Do whatever you like --> @endif
    

    EDIT 2

    I’m adding more content to this answer in order to address some of the issues presented in the comments. I think that your problem is the following:

    $blogs is an empty collection, so it’s defined but it has no elements. For this reason the if(isset($blogs)) statement will evaluate to true passing the first if condition. In your blade template you are making the check {{ $blogs[0]->title or '' }} that is absolutely not equal to <?php isset($blogs[0]->title) ? $blogs[0]->title : '' ?> as pointed out in the comments, but it is an expression that will return true or false, so it will never print out title parameter even if $blogs[0] exists. The problem here is that when checking the condition $blogs[0]->title you are actually accessing the element 0 of the $blogs collection that will trigger the exception Undefined offset: 0 because the collection is actually empty. What i was saying is that in addition to the

    if(count($blogs)) { /* do something */ }
    

    (that checks that $blogs is set and that it’s length is greater than 0) in your template you should do

    {{ isset($blogs[0]->title) ? $blogs[0]->title : '' }}
    

    or more concisely

    {{ $blogs[0]->title ?: '' }}
    

    assuming that the control flow will arrive there only if the $blogs passed the first if. If the issue still persists the problem is elsewhere in your code IMHO.

    Questions:
    Answers:

    If you have an object that’s passed to the view and let’s say your data is “posts” which is being held inside an object like this:
    $obj->posts.

    If you then go and do a foreach loop which would iterate trough every post and print out its parameters like in the example below it works perfectly well when you actually have posts.

    @foreach($obj->posts as $post)
       <h1>$post->title</h1>
       <p>$post->content</p>
    @endforeach
    

    Before doing the loop you’d want to check if attribute has been set with values. You can use isset() for this, and since it’s a special form it can be used as isset($obj->posts) or isset($obj->posts[0]). The difference is that the latter will only check if the array key has any value so if your index key is anything but 0, it’ll return false. For instance you have:

    $foo = ['first' => somevalue1, 'second' => somevalue2];
    isset($foo[0]); //returns false
    isset($foo['first']); //returns true
    isset($foo); //returns true
    

    The way I’d make the check is the following:

    @if(isset($obj->posts))
       @foreach($obj->posts as $post)
          ...
       @endoforeach
    @endif
    

    Questions:
    Answers:

    You can simply solve this with the data_get() helper.

    For example:

    php artisan tink
    Psy Shell v0.8.11 (PHP 7.0.22-0ubuntu0.16.04.1 — cli) by Justin Hileman
    >>> 
    >>> $a = collect([[], null, App\Models\User::find(1)]);
    => Illuminate\Support\Collection {#887
         all: [
           [],
           null,
           App\Models\User {#896
             id: 1,
             name: "user1",
             email: "[email protected]",
             last_name: "Gabrielle",
             first_name: "Rempel",
             deleted_at: null,
             created_at: "2017-08-12 15:32:01",
             updated_at: "2017-09-05 12:23:54",
           },
         ],
       }
    >>> data_get($a[0], 'name', 'nope');
    => "nope"
    >>> data_get($a[1], 'name', 'nope');
    => "nope"
    >>> data_get($a[2], 'name', 'nope');
    => "user1"
    >>> 
    

    So in this case:

    {{ data_get($blogs[0], 'title', '') }}
    

    data_get() will work both on arrays and objects, returning the key or attribute defined in the second param (this can be laravel.dot.notation.style, or just an array), the 3rd param will be the default return value if the object/array or the key/attribute does not exist, the default is null.


    Edit:

    Just saw the request for the extra explanation on why the original code wasn’t working.

    Index 0 simply does not exist on the array/collection that is passed to the view.

    >>> $a = [1 => App\Models\User::find(1)];
    => [
         1 => App\Models\User {#890
           id: 1,
           name: "user1",
           // ... etc
         },
       ]
    >>> $a[0]->name ?: 'nope';
    PHP error:  Undefined offset: 0 on line 1
    >>> $a[1]->name ?: 'nope';
    => "user1"
    

    It doesn’t matter if OP used the blade or default, it doesn’t even make it to the ternary statement because of the missing 0 index on $blogs.


    Edit 2 as requested:

    So the reason you get the Undefined offset: x error is because of the order in which PHP evaluates the code.

    Blade’s or default is behind the scenes nothing more than a ternary statement:

    return preg_replace('/^(?=$)(.+?)(?:\s+or\s+)(.+?)$/si', 'isset($1) ? $1 : $2', $value);
    

    So this will make:

    isset($blogs[0]->title) ? $blogs[0]->title : ''
    

    isset() will check if title on the object is set, but to do so, it will require $blogs[0] to be a valid object. In order to do that, it will try and get the object from the $blogs array at index 0. But since this index does not exist, it will trigger the Exception with an Undefined offset: 0.

    In order to make this work with Blade’s or default, you would first have to ensure that $blogs[0] is defined (and preferably also check that it’s an object, otherwise you’ll get the trying to get property of non-object error, please note that this should not be the responsibility of the view), after that you would be able to use the or default as you would any other time.

    @if (isset($blogs[0]) && is_object($blogs[0]))
        {{ $blogs[0]->title or '' }}
    @else
        // some other default placeholder
    @endif
    

    Basically you will get the same offset error when using data_get(), because index 0 still does not exist.

    {{ data_get($blogs[0], 'title', '') }} // Undefined offset: 0
    

    You could play dirty and do this (this would not pass any code review anywhere and I should not have typed this at all, this is just to illustrate)

    {{ data_get($blogs, '0.title', '') }} // Will display '' as it will check if key 0 exists
    

    Anyway, with data_get() you would still end up doing something like this, as you would need to make sure $blogs[0] is something you can work with:

    @if (isset($blogs[0]))
        {{ data_get($blogs[0], 'title', '') }}
    @else
        // some other default placeholder
    @endif
    

    Bottomline, the best option would be not to rely on indexes like this in your view, this is simply not the responsibility of your view.

    Blade’s or default works perfectly on single variables, but when dealing with object attributes, you would just have to make sure the (parent) object exists when doing so.

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