Dom和XPath刮 - 这里有什么问题？ [英] Dom and XPath scraping - What wrong here?

问题描述

我需要从互联网上的网页中删除一段文字，我正在使用dom和xpath查找数据，但是我似乎无法选择我需要的确切信息。这是我的代码到目前为止，问题是与项目（0） - > nodeValue部分 - 这适用于我的其他scrapes我有另一个页面，但不是这一个。

  $ argos_html = file_get_html（'http://www.argos.co.uk/static/Product/partNumber/9282197/Trail/searchtext%3EIPOD+TOUCH.htm'）; 
 
 $ dom_argos = new DOMDocument（）; 
 $ dom_argos-> loadHTML（$ argos_html）; 
 
 $ xpath_argos = new DOMXpath（$ dom_argos）; 
 
 $ expr_currys =/ html / body / div [4] / div [3] / form / div [2] / div / div [5] / ul / li [3] / span ; 
 $ nodes_argos = $ xpath_argos-> query（$ expr_argos）; 
 
 $ argos_stock_data = $ nodes_argos-> item（0） - > nodeValue; 
  

有没有人会告诉我我哪里错了？因为我总是得到一个错误，它涉及到 - > item（0） - > nodeValue;但是，如果我发表评论，theres没有错误，但是没有收集任何数据...

应该是 - > nodeValue;

我明白这可能是页面结构，但我是全新的！
Thx

解决方案

运行代码，我先得到：

注意：未定义的变量：expr_argos
警告：DOMXPath :: query（）[domxpath.query]：无效的表达式

所以，首先，确保你使用的XPath查询有效的东西 - 例如你应该这样做：

  $ nodes_argos = $ xpath_argos-> query（$ expr_currys）; 
  

而不是您目前拥有的：

  $ nodes_argos = $ xpath_argos-> query（$ expr_argos）; 
  

然后，您会收到以下错误：

 注意：试图获取非对象的财产
  

在以下行：

  $ argos_stock_data = $ nodes_argos-> item（0） - > ;的nodeValue; 
  

基本上，这意味着您正在尝试读取一个属性 nodeValue ，对于不是对象的东西： $ nodes_argos-> item（0）;

我猜你的XPath查询是无效的;所以，调用 xpath（）方法不会返回任何有趣的东西。

你应该检查你的（相当长的时间不容易理解） XPath查询，确保它与HTML页面中的某些内容相匹配。

I need to scrape a length of text from a webpage from the internet, I am using the dom and xpath to find the data, however I cant seem to select the exact information I need. Here is my code so far, the problem is with the item(0)->nodeValue section - this works for my other scrapes i have for another page, however not this one.

$argos_html = file_get_html('http://www.argos.co.uk/static/Product/partNumber/9282197/Trail/searchtext%3EIPOD+TOUCH.htm');

$dom_argos= new DOMDocument();
$dom_argos->loadHTML($argos_html);

$xpath_argos = new DOMXpath($dom_argos);

$expr_currys = "/html/body/div[4]/div[3]/form/div[2]/div/div[5]/ul/li[3]/span";
$nodes_argos = $xpath_argos->query($expr_argos);

$argos_stock_data = $nodes_argos->item(0)->nodeValue;

Could anyone show me where I am going wrong ? because I always get an error, which relates to the ->item(0)->nodeValue; part, however if I comment that out, theres no error, but theres no data collected at all...

Should it perhaps be just ->nodeValue;

I understand this may be down to page structures, but I am new to all of this! Thx

解决方案

Running your code, I first get :

Notice: Undefined variable: expr_argos
Warning: DOMXPath::query() [domxpath.query]: Invalid expression

So, first of all, make sure you are using something valid for your XPath query -- for example, you should have this :

$nodes_argos = $xpath_argos->query($expr_currys);

instead of what you currently have :

$nodes_argos = $xpath_argos->query($expr_argos);

Then, you get the following error :

Notice: Trying to get property of non-object

on the following line :

$argos_stock_data = $nodes_argos->item(0)->nodeValue;

Basically, this means you are trying to read a property, nodeValue, on something that is not an object : $nodes_argos->item(0);

I'm guessing your XPath query is not valid ; so, the call to the xpath() method doesn't return anything interesting.

You should check your (quite a bit too long to be easy to understand) XPath query, making sure it matches something in your HTML page.

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