数据表JSON解析错误

Question

我正在尝试在我的laravel项目中的数据表中显示一些数据，但是我遇到一个错误，表示我的数据格式不正确我知道数据格式正确，因为我有其他数据表使用相同的数据这是我的控制器：

<?php

namespace App\Http\Controllers;

use Datatable;
use View;
use App\Models\EC2Instance;
use App\Models\ChangedProperties;
use Illuminate\Support\Facades\Input;
use App\Models\ChangelogItem;

class ChangedPropertiesController extends Controller {

    protected $layout = 'changed_properties';


    public function details($changelog_item_id) 
            {


 $changed_property = new ChangedProperties;

        $changed_properties = $changed_property->where('changelog_item_id', $changelog_item_id)->get();

        $table = Datatable::table()
                ->addColumn(
                        'Changed Property', 'Change Type', 'Changelog Item ID', 'Previous Value', 'Updated Value'
                )
                ->setUrl('/changed_properties/'. $changed_properties)
                ->noScript();





        return View::make('changed_properties')
                         ->with('property',$changed_properties)
                        ->with('table', $table);
        }

    public function instance_details($changelog_item_id)
            {


        $query = ChangedProperties::select(array('resource_id',
                            'resource_type',
                            'changed_property',
                            'change_type',
                            'previous_value',
                             'updated_value',
                             'changelog_item_id'
                             ))
                        ->get();




        return Datatable::collection($query)

                        ->showColumns(
                                 'changed_property', 'change_type','changelog_item_id', 'previous_value', 'updated_value')
                        ->searchColumns( 'changed_property', 'change_type', 'previous_value', 'updated_value')
                        ->orderColumns( 'changed_property', 'change_type', 'previous_value', 'updated_value'
                        )
                        ->make();
    }

}

和路线：

/Homepage Route

Route::get('/', 'CRUDController@users');



// Route which populates datatable in homepage
Route::get('search', array('as' => 'instance.search', 'uses' => 'CRUDController@instances'));


//route which renders instance details
Route::get('/instance_details/{instance_id}','DetailsController@details');


//route which links to individual instance details
Route::get('/ec2_instance/{resource_type}/{resource_id}',array('as'=>'InstanceId', 'uses'=>'DetailsController@instance_details'));

//route which renders changed properties for changelog item
Route::get('/changed_properties/{changelog_item_id}/','ChangedPropertiesController@details');

//route which links to individual instance details
Route::get('/changed_properties/{changlog_item_id}/',array('as'=>'ChangelogItemId', 'uses'=>'ChangedPropertiesController@instance_details'));

Route::resource('sns', 'SNSController');