Question

我一直收到这个错误：

Argument 1 passed to myFunction() must be an instance of SimpleXMLElement, null given

这是我的代码：

function myFunction(SimpleXMLElement $order_status_response_element) {
    // Get any invoices firstly.
    $invoice_details_element_array = $order_status_response_element->xpath('//Detail/RefInfo/RefIDQual[text()="IN"]/parent::*/parent::*');
    $invoice_numbers_element_array = $order_status_response_element->xpath('//Detail/RefInfo/RefIDQual[text()="IN"]/parent::RefInfo/RefID');
    $non_invoice_details_element_array = $order_status_response_element->xpath('//Detail[not(RefInfo/RefIDQual[text()="IN"])]');
    if(count($non_invoice_details_element_array) > 1) throw new Exception('More than one instance of non-invoiced details in array! Aborting!');
    $non_invoice_details_element = $non_invoice_details_element_array[0];
    echo("non_invoice_details_element is a SimpleXMLElement, true? ".is_a($non_invoice_details_element,'SimpleXMLElement')."\n");


    $non_invoice_detail = sXMLtoArray($non_invoice_details_element);
    ^^^ERROR HAPPENS HERE^^^
}

/**
* Return an array, given a SimpleXMLElement object.
*
* @param SimpleXMLElement $elem
* @return array
*/
function sXMLtoArray(SimpleXMLElement $elem) {
    return json_decode(json_encode($elem),TRUE);
}

现在我得到的输出看起来像这样：

non_invoice_details_element is a SimpleXMLElement, true? 1

Argument 1 passed to sXMLtoArray() must be an instance of SimpleXMLElement, null given, called in {path} on line 2033 and defined {paths}

因此，如果is_a()告诉我它确实是一个SimpleXMLElement，那么当它传递给sXMLtoArray()函数时为什么认为它为空？如果它不是SimpleXMLElement，那么它之前会抛出异常，因为$ non_invoice_details_element_array将是零长度，因为xpath不存在。

这里到底有什么不对？

为什么我会收到此错误：＆＃34;传递给myFunction（）的参数1必须是SimpleXMLElement的一个实例，null给出＆＃34;？

0 个答案: