Laravel，从select2中的数据库中获取选定的值

Question

I am trying to show all selected values from database to multiple select2.So when I want to add other events I can add them.

Offer tables:
id:1
title: event1
events: 17,6,8

column events has id of all events selected.

This is what I do:

public function edit($id)
    {
        $offer=Offers::find($id);
         $events=Events::all();

        $explode=  explode(',', $offer->events);


        return view('edit',['offer'=>$offer,'events'=>$events,'explode'=>$explode]);
    }

Blade:

<div class="form-group m-form__group row">
    <label class="col-xl-3 col-lg-3 col-form-label">****</label>
    <div class="col-xl-9 col-lg-9">
        <select class="form-control m-select2" id="m_select2_3" name="events[]" multiple="multiple">
            <optgroup label="Events">
                @foreach($events as $event)
                    @foreach($explode as $item)
                        <option value="{{$event->id}}"  {{ $item == $event->id ? 'selected="selected"' : ''}}>{{$event->title}}</option>
                    @endforeach
                @endforeach
            </optgroup>
        </select>
    </div>
</div>

So when i select the value it shows three times repeated values

Answer 1

You're loading all the database events in the $events variable and not the events associated with the offer. You should be doing something like this:

$events = Event::find(explode(',', Offer::find($id)->events));

Having said that, it would be best to use relationships for that instead of manually setting the ids https://laravel.com/docs/5.7/eloquent-relationships

Answer 2

Maybe when you are getting events, you are getting duplicated, try this:

public function edit($id)
    {
        $offer=Offers::find($id);
         $events=Events::all();

        $explode =  array_values(array_unique(explode(',', $offer->events)));



        return view('edit',['offer'=>$offer,'events'=>$events,'explode'=>$explode]);
    }

However, if that's the case, you should know that you offers table do not have duplicated event at the first place so you might want to change the script which saves events as well for the offer to remove duplicate entries.

Also, I don't know if your "events" table contains duplicated events as well. Please check that and remove any duplicated values from your "events" table and if you cant then use same code for that as well like so in your controller:

$events = array_values(array_unique(Events::all()->toArray()));

I hope it helps