php - 将XML数据插入数据库失败

我在尝试将XML数据插入数据库时​​遇到问题。在过去的两天里，我一直在Google上进行研究，但我仍在努力。如果有人可以提供帮助，将不胜感激。非常感谢你。

尝试插入数据时收到以下错误消息：


  注意：尝试获取非对象的属性
  第13行的insert_into_database.php
  
  致命错误：在以下位置调用成员函数item（）上的null
  第13行的insert_into_database.php


insert_into_database.php

<?php

$db = new PDO('mysql:host=localhost;dbname=data', 'root', '');

$xmldoc = new DOMDocument();
$xmldoc->load('data.xml');

$xmldata = $xmldoc->getElementsByTagName('group');
$xmlcount = $xmldata->length;

for ($i=0; $i < $xmlcount; $i++) {
    $id = $xmldata->item($i)->getElementsByTagName('id')->item(0)->childNodes->item(0)->nodeValue;
    $group = $xmldata->item($i)->getElementsByTagName('group')->item(0)->childNodes->item(0)->nodeValue;
    $category = $xmldata->item($i)->getElementsByTagName('category')->item(0)->childNodes->item(0)->nodeValue;
    $question = $xmldata->item($i)->getElementsByTagName('question')->item(0)->childNodes->item(0)->nodeValue;
    $a = $xmldata->item($i)->getElementsByTagName('a')->item(0)->childNodes->item(0)->nodeValue;
    $b = $xmldata->item($i)->getElementsByTagName('b')->item(0)->childNodes->item(0)->nodeValue;
    $c = $xmldata->item($i)->getElementsByTagName('c')->item(0)->childNodes->item(0)->nodeValue;
    $d = $xmldata->item($i)->getElementsByTagName('d')->item(0)->childNodes->item(0)->nodeValue;
    $stmt = $db->prepare("insert into xml values(?,?,?,?,?,?,?,?)");
    $stmt->bindParam(1,$group);
    $stmt->bindParam(2,$category);
    $stmt->bindParam(3,$question);
    $stmt->bindParam(4,$a);
    $stmt->bindParam(5,$b);
    $stmt->bindParam(6,$c);
    $stmt->bindParam(7,$d);
    $stmt->execute();
    printf($name.'<br />');
}

?>

data.xml

<?xml version="1.0" encoding="UTF-8"?>

<questions>
<group name="Question Group 1">
    <id>1</id>
    <category>Category A</category>
    <question name="Question 1" a="Answer 1" b="Answer 2" c="Answer 3" d="Answer 4"/>
    <question name="Question 2" a="Answer 1" b="Answer 2" c="Answer 3" d="Answer 4"/>
    <question name="Question 3" a="Answer 1" b="Answer 2" c="Answer 3" d="Answer 4"/>
    <question name="Question 4" a="Answer 1" b="Answer 2" c="Answer 3" d="Answer 4"/>
    <question name="Question 5" a="Answer 1" b="Answer 2" c="Answer 3" d="Answer 4"/>
</group>
<group name="Question Group 2">
    <id>2</id>
    <category>Category B</category>
    <question name="Question 1" a="Answer 1" b="Answer 2" c="Answer 3" d="Answer 4"/>
    <question name="Question 2" a="Answer 1" b="Answer 2" c="Answer 3" d="Answer 4"/>
    <question name="Question 3" a="Answer 1" b="Answer 2" c="Answer 3" d="Answer 4"/>
    <question name="Question 4" a="Answer 1" b="Answer 2" c="Answer 3" d="Answer 4"/>
    <question name="Question 5" a="Answer 1" b="Answer 2" c="Answer 3" d="Answer 4"/>
</group>
<group name="Question Group 3">
    <id>3</id>
    <category>Category C</category>
    <question name="Question 1" a="Answer 1" b="Answer 2" c="Answer 3" d="Answer 4"/>
    <question name="Question 2" a="Answer 1" b="Answer 2" c="Answer 3" d="Answer 4"/>
    <question name="Question 3" a="Answer 1" b="Answer 2" c="Answer 3" d="Answer 4"/>
    <question name="Question 4" a="Answer 1" b="Answer 2" c="Answer 3" d="Answer 4"/>
    <question name="Question 5" a="Answer 1" b="Answer 2" c="Answer 3" d="Answer 4"/>
</group>
</questions>

最佳答案

如果您只想获取组，请执行以下操作：

$group = $xmldata->item($i)->getAttribute('name');

总体而言，您需要像这样更改代码：

$db = new PDO('mysql:host=localhost;dbname=data', 'root', '');

$xmldoc = new DOMDocument();
$xmldoc->load('data.xml');

$xmldata = $xmldoc->getElementsByTagName('group');
$xmlcount = $xmldata->length;

for($i = 0; $i < $xmlcount; ++$i){
    $id = $xmldata->item($i)->getElementsByTagName('id')->item(0)->nodeValue;
    $group = $xmldata->item($i)->getAttribute('name');
    $category = $xmldata->item($i)->getElementsByTagName('category')->item(0)->nodeValue;
    $questioncount = $xmldata->item(0)->getElementsByTagName('question')->length;

    for($j = 0; $j < $questioncount; ++$j){
        $question = $xmldata->item($i)->getElementsByTagName('question')->item($j)->getAttribute('name');
        $a = $xmldata->item($i)->getElementsByTagName('question')->item($j)->getAttribute('a');
        $b = $xmldata->item($i)->getElementsByTagName('question')->item($j)->getAttribute('b');
        $c = $xmldata->item($i)->getElementsByTagName('question')->item($j)->getAttribute('c');
        $d = $xmldata->item($i)->getElementsByTagName('question')->item($j)->getAttribute('d');

        // Do your database operations

    }
}