Laravel在database.php加上强制mysql预处理后出现问题?

Question

在database.php加上mysql预处理

先贴出代码：

$permissions = [];
$user->roles()->with('perms')->get()->pluck('perms')->map(function ($item, $key) use (&$permissions) {
            $child = $item->where('is_display', 1)->pluck('id');

            var_dump($child);
            if ($key == 0) {
                $permissions = $child->toArray();
            } else {
                $permissions = array_merge($permissions, $child->toArray());
            }
});

$item打印出来是一个eloquent对象:

object(Illuminate\Database\Eloquent\Collection)[604]
  protected 'items' => 
    array (size=46)
      0 => 
        object(App\Models\Permission)[528]
          protected 'table' => string 'permissions' (length=11)
          protected 'connection' => null
          protected 'primaryKey' => string 'id' (length=2)
          protected 'perPage' => int 15
          public 'incrementing' => boolean true
          public 'timestamps' => boolean true
          protected 'attributes' => 
            array (size=9)
              'id' => string '1' (length=1)
              'parent_id' => string '0' (length=1)
              'name' => string '/' (length=1)
              'display_name' => string '管理后台' (length=12)
              'description' => string '管理后台' (length=12)
              'is_display' => string '1' (length=1)
              'icon' => string 'fa-dashboard' (length=12)
              'created_at' => string '2017-01-05 16:34:04' (length=19)
              'updated_at' => string '2017-01-05 16:34:04' (length=19)
          protected 'original' => 
            array (size=11)
              'id' => string '1' (length=1)
              'parent_id' => string '0' (length=1)
              'name' => string '/' (length=1)
              'display_name' => string '管理后台' (length=12)
              'description' => string '管理后台' (length=12)
              'is_display' => string '1' (length=1)
              'icon' => string 'fa-dashboard' (length=12)
              'created_at' => string '2017-01-05 16:34:04' (length=19)
              'updated_at' => string '2017-01-05 16:34:04' (length=19)
              'pivot_role_id' => string '1' (length=1)
              'pivot_permission_id' => string '1' (length=1)
          protected 'relations' => 
            array (size=1)
              'pivot' => 
                object(Illuminate\Database\Eloquent\Relations\Pivot)[530]
                  protected 'parent' => 
                    object(App\Models\Role)[590]
                      protected 'fillable' => 
                        array (size=3)
                          0 => string 'name' (length=4)
                          1 => string 'display_name' (length=12)
                          2 => string 'description' (length=11)
                      protected 'table' => string 'roles' (length=5)
                      protected 'connection' => null
                      protected 'primaryKey' => string 'id' (length=2)
                      protected 'perPage' => int 15
                      public 'incrementing' => boolean true
                      public 'timestamps' => boolean true
                      protected 'attributes' => 
                        array (size=0)
                          empty
                      protected 'original' => 
                        array (size=0)
                          empty
                      protected 'relations' => 
                        array (size=0)
                          empty
                      protected 'hidden' => 
                        array (size=0)
                          empty
                      protected 'visible' => 
                        array (size=0)
                          empty
                      protected 'appends' => 
                        array (size=0)
                          empty
                      protected 'guarded' => 
                        array (size=1)
                          0 => string '*' (length=1)
                      protected 'dates' => 
                        array (size=0)
                          empty
                      protected 'dateFormat' => null
                      protected 'casts' => 
                        array (size=0)
                          empty
                      protected 'touches' => 
                        array (size=0)
                          empty
                      protected 'observables' => 
                        array (size=0)
                          empty
                      protected 'with' => 
                        array (size=0)
                          empty
                      protected 'morphClass' => null
                      public 'exists' => boolean false
                      public 'wasRecentlyCreated' => boolean false
                  protected 'foreignKey' => string 'role_id' (length=7)
                  protected 'otherKey' => string 'permission_id' (length=13)
                  protected 'guarded' => 
                    array (size=0)
                      empty
                  protected 'connection' => null
                  protected 'table' => string 'permission_role' (length=15)
                  protected 'primaryKey' => string 'id' (length=2)
                  protected 'perPage' => int 15
                  public 'incrementing' => boolean true
                  public 'timestamps' => boolean false
                  protected 'attributes' => 
                    array (size=2)
                      'role_id' => string '1' (length=1)
                      'permission_id' => string '1' (length=1)
                  protected 'original' => 
                    array (size=2)
                      'role_id' => string '1' (length=1)
                      'permission_id' => string '1' (length=1)
                  protected 'relations' => 
                    array (size=0)
                      empty
                  protected 'hidden' => 
                    array (size=0)
                      empty
                  protected 'visible' => 
                    array (size=0)
                      empty
                  protected 'appends' => 
                    array (size=0)
                      empty
                  protected 'fillable' => 
                    array (size=0)
                      empty
                  protected 'dates' => 
                    array (size=0)
                      empty
                  protected 'dateFormat' => null
                  protected 'casts' => 
                    array (size=0)
                      empty
                  protected 'touches' => 
                    array (size=0)
                      empty
                  protected 'observables' => 
                    array (size=0)
                      empty
                  protected 'with' => 
                    array (size=0)
                      empty
                  protected 'morphClass' => null
                  public 'exists' => boolean true
                  public 'wasRecentlyCreated' => boolean false
          protected 'hidden' => 
            array (size=0)
              empty
          protected 'visible' => 
            array (size=0)
              empty
          protected 'appends' => 
            array (size=0)
              empty
          protected 'fillable' => 
            array (size=0)
              empty
          protected 'guarded' => 
            array (size=1)
              0 => string '*' (length=1)
          protected 'dates' => 
            array (size=0)
              empty
          protected 'dateFormat' => null
          protected 'casts' => 
            array (size=0)
              empty
          protected 'touches' => 
            array (size=0)
              empty
          protected 'observables' => 
            array (size=0)
              empty
          protected 'with' => 
            array (size=0)
              empty
          protected 'morphClass' => null
          public 'exists' => boolean true
          public 'wasRecentlyCreated' => boolean false
          
          ................

为什么$child是empty的？

Answer 1

$item对象对应的is_display字段值为string类型的，导致$child为空