how to Extract Checkbox values from the Database to be updated in view

I am trying to update the checkbox values stored in the database but I can't get them to the update view form

Here is my update method in UserController

 public function update(Request $request, $id)
    {
        $this->validate($request,[
            'email' => 'email',
            'phone' => 'min:10|max:15',
            'gender' => 'required',
            'identity' => 'required',
            'password' => 'string|min:8|confirmed',
            'street' => 'required',
            'suburb' => 'required',
            'city' => 'required',            
            'province' => 'required|not_in:0',
            'code' => 'required',
            'school' => 'required',
            'grade' => 'required|not_in:0',
            'subjects' => 'required'
        ]);
    
        $user = User::find($id);
        
        $user->update($request->all());

           if($user->types == 'Learner'){
            $learner = Learner::where('user_id', $id)->first();
            $learner->gender = $request->input('gender');
            $learner->identity = $request->input('identity');
            $learner->street = $request->input('street');
            $learner->suburb = $request->input('suburb');
            $learner->city = $request->input('city');
            $learner->province = $request->input('province');
            $learner->code = $request->input('code');
            $learner->school = $request->input('school');
            $learner->grade = $request->input('grade');
            $learner->subjects = $request->input('subjects');            
            $learner->save();
            return redirect()->back()->with('message', 'User Updated Successfully');
           }

My Learner Model

<?php

namespace App;

use Illuminate\Database\Eloquent\Model;
// use App\User;

class Learner extends Model //class Learner extends User
{
    protected $guarded = [];
    protected $table = "learners";
    protected $casts = [
        'subjects' => 'array',
    ];
    public function user()
    {
        return $this->belongsTo('App\User');
    }

    public function setSubjects($value)
    {
        $this->attributes['subjects'] = json_encode($value);
    }

    public function getSubjects($value)
    {
        return $this->attributes['subjects'] = json_decode($value);
    }
}

edit.blade.php

<div class="col-md-2 font-weight-bold pt-2">Subjects:</div>
                            <div class="col-md-10">                            
                                <div class="form-group">
                                    <div class="custom-control custom-checkbox mt-2">
                                        <input type="checkbox" class="custom-control-input @error('subjects') is-invalid @enderror" id="Mathematics" name="subjects[]" value="Mathematics" @foreach($user as $subject) {{ ($user->learner->subjects=='Mathematics') ? 'checked' : '' }} @endforeach/>
                                        <label class="custom-control-label" for="Mathematics">Mathematics</label>
                                    </div>
                                    <div class="custom-control custom-checkbox mt-2">
                                        <input type="checkbox" class="custom-control-input @error('subjects') is-invalid @enderror" id="Physical Science" name="subjects[]" value="Physical Science" {{ ($user->learner->subjects=='Physical Science')? 'checked' : '' }}/>
                                        <label class="custom-control-label" for="Physical Science">Physical Science</label>
                                    </div>
                                    <div class="custom-control custom-checkbox mt-2">
                                        <input type="checkbox" class="custom-control-input @error('subjects') is-invalid @enderror" id="Accounting" name="subjects[]" value="Accounting" {{ ($user->learner->subjects=='Accounting')? 'checked' : '' }}/>
                                        <label class="custom-control-label" for="Accounting">Accounting</label>
                                    </div>
                                    <div class="custom-control custom-checkbox mt-2">
                                        <input type="checkbox" class="custom-control-input @error('subjects') is-invalid @enderror" id="Life Science" name="subjects[]" value="Life Science" {{ ($user->learner->subjects=='Life Science')? 'checked' : '' }}/>
                                        <label class="custom-control-label" for="Life Science">Life Science</label>
                                    </div>
                                    <div class="custom-control custom-checkbox mt-2">
                                        <input type="checkbox" class="custom-control-input @error('subjects') is-invalid @enderror" id="Geography" name="subjects[]" value="Geography" {{ ($user->learner->subjects=='Geography')? 'checked' : '' }}/>
                                        <label class="custom-control-label" for="Geography">Geography</label>
                                    </div>
                                @error('subjects')
                                    <span class="invalid-feedback" role="alert">
                                        <strong>{{ $message }}</strong>
                                    </span>
                                @enderror
                                </div>
                            </div>

and when I try to loop the values in the show method it gives an error

show.blade.php

<tr>
        <th scope="row">Subjects</th>
               <td> 
                      @foreach($user->subjects as subject)                                  
                            {{ subjects }}
                       @endforeach
              </td>
</tr>                                	

and in my database the checkbox values are stored stored like this:

subjects: ["Mathematics","Physical Science","Accounting"]