Re: Creating a DOM Document from HTTP Request of XML failing

On Tue, Apr 6, 2010 at 9:05 AM, Boris Zbarsky <[email protected]> wrote:
> On 4/6/10 12:01 PM, Cris wrote:
>>
>> No headers. That XML was the entire output. I'm guessing this is the
>> problem.
>
> Yep.  Either the server needs to claim the output is XML or you need to tell
> your XHR to treat the data as XML no matter what the server says.
>
> -Boris
>
 
Thank you Boris.   I am successfully able to create the Document. 

Walking through the document, I am able to GetTagName,  successfully, eg I get "first_name", "last_name", "uid", as tag names, but when call element->GetAttribute("value")  I get an empty string result.   Should I not be querying the element's value?  What should I be doing?


The XML code is below, and the C++ code that is causing the error is below.

Thanks,

-cris
-------


<?xml version="1.0" encoding="UTF-8"?>
<users_getInfo_response xmlns="http://api.facebook.com/1.0/" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://api.facebook.com/1.0/facebook.xsd" list="true">
  <user>
    <about_me xsi:nil="true"/>
    <first_name>Cris</first_name>
    <last_name>Rys</last_name>
    <uid>693893361</uid>
  </user>
</users_getInfo_response>

-------

	nsCOMPtr<nsIDOMDocument> document;
	rv = inXMLHttpRequest->GetResponseXML(getter_AddRefs(document));
	NS_ENSURE_SUCCESS(rv, rv);
	NS_ENSURE_TRUE(document, NS_ERROR_FAILURE);
  
	nsCOMPtr<nsIDOMNodeList> userNodeList;
	rv = document->GetElementsByTagName(NS_LITERAL_STRING("user"),  getter_AddRefs(userNodeList));
	NS_ENSURE_STATE(userNodeList);
	NS_ENSURE_SUCCESS(rv, rv);

	PRUint32 userNodeListLength = 0;
	rv = userNodeList->GetLength(&userNodeListLength);
	NS_ENSURE_SUCCESS(rv, rv);

	nsCOMPtr<nsIDOMNode> userNode;
	rv = userNodeList->Item(0, getter_AddRefs(userNode));
	NS_ENSURE_SUCCESS(rv, rv);

	nsCOMPtr<nsIDOMNodeList> childNodes;
	rv = userNode->GetChildNodes(getter_AddRefs(childNodes));
	NS_ENSURE_SUCCESS(rv, rv);

	PRUint32 childNodeListLength = 0;
	rv = childNodes->GetLength(&childNodeListLength);
	NS_ENSURE_SUCCESS(rv, rv);
	
	nsString first_name, last_name, pic_square,profile_url, uidStr;
	uint64_t uid = 0;

	for(PRUint32 i = 0; i < childNodeListLength; ++i) 
	{
		nsCOMPtr<nsIDOMNode> domNode;
		rv = childNodes->Item(i, getter_AddRefs(domNode));
		NS_ENSURE_SUCCESS(rv, rv);

		nsCOMPtr<nsIDOMElement> element = do_QueryInterface(domNode, &rv);
		if(NS_FAILED(rv)) 
		{
		  continue;
		}

		nsString tagName;
		rv = element->GetTagName(tagName);  // successfully gets names of "first_name", "last_name", "uid"
		NS_ENSURE_SUCCESS(rv, rv);

		nsString value;
		rv = element->GetAttribute(NS_LITERAL_STRING("value"), value);  // but attribute value is an empty string
		if(NS_FAILED(rv)) 
		{
		  continue;
		}

		if(tagName.EqualsLiteral("first_name")) 
		{
			first_name = value; 
		}
		else if(tagName.EqualsLiteral("last_name")) 
		{
			last_name = value;
		} 
		else if(tagName.EqualsLiteral("uid")) 
		{
			uidStr = value;
		} 
		
	}