Laravel 5读取Json文件给出错误`Response.php line 403`

I want to read json file from database directory, but give The Response content must be a string or object implementing __toString(), "boolean" given. error. Bellow is my code :

  $json = file_get_contents('database/query_templates/course.json');
  $data = json_decode($json, TRUE);              

  echo '<pre/>'; print_r($data); exit;

course.json file content :

{
  "post_filter" : {
     "operator" : [
        {
           "operator" : [
              {
                "range" : {
                    "created_at" : {
                        "gte" : "log_start_date",
                        "lte" : "log_end_date",
                        "format" : "yyyy-MM-dd"
                    }
                }
            },
            {
                "terms" : {
                    "search_param_user_action.id" : "user_select_array"
                }
            }
        ]
    },
    {
        "operator" : [
            {
                "operator" : [
                    "conduct_days_multi"
                ]
            },
            {
                "operator" : [
                    "dropdowns"
                ]
            }
        ]
    },
    {
        "query" : {
            "multi_match" : {
                "query" : "x",
                "fields" : [
                    "resource_search_columns"
                ],

                "operator" : "operator"
            }
         }
      }
    ]
  }
}

for any help thanks.

Sometimes some php releasees not supported get_file_contents() or this func return type string but not only return string everytime, sometimes return boolean value bacause it's working on the byte codes, you can try traditional file operation methods or you can try convert to string.