How to use function old() in Blade template to get the last element of array

Question

How to get the last element of the array 'g3' inside the old() function without knowing the number of elements.

<select name="g3[]" multiple="multiple">
        <option value="1" @if (old('g3')=="1" ) {{ 'selected' }} @endif >lifting</option>
        <option value="2" @if (old('g3')=="2" ) {{ 'selected' }} @endif >jogging</option>
        <option value="3" @if (old('g3')=="3" ) {{ 'selected' }} @endif >sleeping</option>
      </select>

      <div {!! old('g3') != 3 ? '':' style="display: none"' !!}> Not to be seen</div>

How to get the selected item within a div.

Answer 1

As mentioned by @apokryfos in the comments:

\Illuminate\Support\Arr::last(old('g3') ?? []) != 3

---

Additional instructions

Based on your comment, the following demo should be sufficient:

<div>
    @php($data = [1 => "举重", 2 => "慢跑", 3 => "睡觉"])

    <select name="g3[]" id="g3" multiple>
        @foreach($data as $id => $v)
            <option value="{{$id}}" {{in_array($id, old('g3') ?? []) ? 'selected' : ''}}>
                {{$v}}
            </option>
        @endforeach
    </select>

    <div style="display: {{!in_array(array_flip($data)["睡觉"], old('g3') ?? []) ? 'none': ''}};"> 不可见</div>
</div>

Answer 2

If your old value is array, you can use in_array instead.
Check if old('g3') exists, then check if value is in the array old('g3')

<select name="g3[]" multiple="multiple">
   <option value="1" @if (old('g3') && in_array('1', old('g3'))) selected @endif >lifting</option>
   <option value="2" @if (old('g3') && in_array('2', old('g3'))) selected @endif >jogging</option>
   <option value="3" @if (old('g3') && in_array('3', old('g3'))) selected @endif >sleeping</option>  
</select>

How to get the last element of the array, you can try this
array_values() function returns an array containing all the values ​​of the array.
Tip: The returned array will have numeric keys, starting from 0 and increasing gradually.

@if (old('g3'))
   @php
      $size = count(array_values(old('g3')));
      $lastElement = old('g3')[$size - 1];
   @endphp
   // 做一些操作
@endif