php - 如何将这个 PHP 对象数组转换为 json？

Question

我有一个包含 10 个对象的数组，我正在尝试将其转换为 JSON。该数组存储在名为 $invoices 的变量中。以下是仅简化为第一个对象的 var_dump($invoices) 的输出。

我试过以下方法:

$invoices = json_encode($invoices, FALSE);
$invoices = json_encode($invoices, TRUE);
$invoices = json_encode($invoices, JSON_UNESCAPED_UNICODE);

但是，输出总是:

string(31) "[{},{},{},{},{},{},{},{},{},{}]"

如何将此数组正确转换为 JSON？

注意:我运行的是 PHP 5.5.9

更新:

事实证明问题是由于 json_encode 不能与“ protected 成员变量”一起使用。如果我无权访问创建它们的类，有没有办法将这些变量声明为公共(public)变量？

array(10) {
  [0]=>
  object(QuickBooks_IPP_Object_Invoice)#285 (1) {
    ["_data":protected]=>
    array(22) {
      ["Id"]=>
      array(1) {
        [0]=>
        string(6) "{-224}"
      }
      ["SyncToken"]=>
      array(1) {
        [0]=>
        string(1) "0"
      }
      ["MetaData"]=>
      array(1) {
        [0]=>
        object(QuickBooks_IPP_Object_MetaData)#282 (1) {
          ["_data":protected]=>
          array(2) {
            ["CreateTime"]=>
            array(1) {
              [0]=>
              string(25) "2014-12-07T09:48:47-08:00"
            }
            ["LastUpdatedTime"]=>
            array(1) {
              [0]=>
              string(25) "2014-12-07T09:48:47-08:00"
            }
          }
        }
      }
      ["CustomField"]=>
      array(1) {
        [0]=>
        object(QuickBooks_IPP_Object_CustomField)#292 (1) {
          ["_data":protected]=>
          array(3) {
            ["DefinitionId"]=>
            array(1) {
              [0]=>
              string(4) "{-1}"
            }
            ["Name"]=>
            array(1) {
              [0]=>
              string(6) "Crew #"
            }
            ["Type"]=>
            array(1) {
              [0]=>
              string(10) "StringType"
            }
          }
        }
      }
      ["DocNumber"]=>
      array(1) {
        [0]=>
        string(4) "1038"
      }
      ["TxnDate"]=>
      array(1) {
        [0]=>
        string(10) "2014-12-07"
      }
      ["Line"]=>
      array(2) {
        [0]=>
        object(QuickBooks_IPP_Object_Line)#263 (1) {
          ["_data":protected]=>
          array(5) {
            ["Id"]=>
            array(1) {
              [0]=>
              string(4) "{-1}"
            }
            ["LineNum"]=>
            array(1) {
              [0]=>
              string(1) "1"
            }
            ["Amount"]=>
            array(1) {
              [0]=>
              string(9) "155555.00"
            }
            ["DetailType"]=>
            array(1) {
              [0]=>
              string(19) "SalesItemLineDetail"
            }
            ["SalesItemLineDetail"]=>
            array(1) {
              [0]=>
              object(QuickBooks_IPP_Object_SalesItemLineDetail)#765 (1) {
                ["_data":protected]=>
                array(2) {
                  ["ItemRef"]=>
                  array(1) {
                    [0]=>
                    string(4) "{-3}"
                  }
                  ["TaxCodeRef"]=>
                  array(1) {
                    [0]=>
                    string(6) "{-NON}"
                  }
                }
              }
            }
          }
        }
        [1]=>
        object(QuickBooks_IPP_Object_Line)#748 (1) {
          ["_data":protected]=>
          array(3) {
            ["Amount"]=>
            array(1) {
              [0]=>
              string(9) "155555.00"
            }
            ["DetailType"]=>
            array(1) {
              [0]=>
              string(18) "SubTotalLineDetail"
            }
            ["SubTotalLineDetail"]=>
            array(1) {
              [0]=>
              string(0) ""
            }
          }
        }
      }
      ["TxnTaxDetail"]=>
      array(1) {
        [0]=>
        object(QuickBooks_IPP_Object_TxnTaxDetail)#287 (1) {
          ["_data":protected]=>
          array(1) {
            ["TotalTax"]=>
            array(1) {
              [0]=>
              string(1) "0"
            }
          }
        }
      }
      ["CustomerRef"]=>
      array(1) {
        [0]=>
        string(5) "{-11}"
      }
      ["BillAddr"]=>
      array(1) {
        [0]=>
        object(QuickBooks_IPP_Object_BillAddr)#284 (1) {
          ["_data":protected]=>
          array(7) {
            ["Id"]=>
            array(1) {
              [0]=>
              string(5) "{-11}"
            }
            ["Line1"]=>
            array(1) {
              [0]=>
              string(13) "1045 Main St."
            }
            ["City"]=>
            array(1) {
              [0]=>
              string(13) "Half Moon Bay"
            }
            ["CountrySubDivisionCode"]=>
            array(1) {
              [0]=>
              string(2) "CA"
            }
            ["PostalCode"]=>
            array(1) {
              [0]=>
              string(5) "94213"
            }
            ["Lat"]=>
            array(1) {
              [0]=>
              string(10) "37.4559621"
            }
            ["Long"]=>
            array(1) {
              [0]=>
              string(11) "-122.429939"
            }
          }
        }
      }
      ["ShipAddr"]=>
      array(1) {
        [0]=>
        object(QuickBooks_IPP_Object_ShipAddr)#814 (1) {
          ["_data":protected]=>
          array(7) {
            ["Id"]=>
            array(1) {
              [0]=>
              string(5) "{-11}"
            }
            ["Line1"]=>
            array(1) {
              [0]=>
              string(13) "1045 Main St."
            }
            ["City"]=>
            array(1) {
              [0]=>
              string(13) "Half Moon Bay"
            }
            ["CountrySubDivisionCode"]=>
            array(1) {
              [0]=>
              string(2) "CA"
            }
            ["PostalCode"]=>
            array(1) {
              [0]=>
              string(5) "94213"
            }
            ["Lat"]=>
            array(1) {
              [0]=>
              string(10) "37.4559621"
            }
            ["Long"]=>
            array(1) {
              [0]=>
              string(11) "-122.429939"
            }
          }
        }
      }
      ["DueDate"]=>
      array(1) {
        [0]=>
        string(10) "2015-01-06"
      }
      ["TotalAmt"]=>
      array(1) {
        [0]=>
        string(9) "155555.00"
      }
      ["ApplyTaxAfterDiscount"]=>
      array(1) {
        [0]=>
        string(5) "false"
      }
      ["PrintStatus"]=>
      array(1) {
        [0]=>
        string(11) "NeedToPrint"
      }
      ["EmailStatus"]=>
      array(1) {
        [0]=>
        string(6) "NotSet"
      }
      ["Balance"]=>
      array(1) {
        [0]=>
        string(9) "155555.00"
      }
      ["Deposit"]=>
      array(1) {
        [0]=>
        string(1) "0"
      }
      ["AllowIPNPayment"]=>
      array(1) {
        [0]=>
        string(5) "false"
      }
      ["AllowOnlinePayment"]=>
      array(1) {
        [0]=>
        string(5) "false"
      }
      ["AllowOnlineCreditCardPayment"]=>
      array(1) {
        [0]=>
        string(5) "false"
      }
      ["AllowOnlineACHPayment"]=>
      array(1) {
        [0]=>
        string(5) "false"
      }
    }
  }
  [1]=>
  object(QuickBooks_IPP_Object_Invoice)#830 (1) {
    ["_data":protected]=>
    array(22) {
    ...
    ...

Answer 1

最好的方法是执行JsonSerializable类并定义 jsonSerialize() 函数

例子:

class MyObj implements JsonSerializable{
    protected $id;
    protected $name;

    function getId() { return $this->$id; }
    function getName() { return $this->$name; }
  
     public function jsonSerialize() {
                return [
                'Id' => $this->getId(),
                'Name' => $this->getName()
            ];
        }
}

// $arrofobj is array of objects of type MyObj 
json_encode($arrofobj);  //this will convert array of objects to JSON