Question

I’ve set up a parser that is consuming an asmx web service, and .NET is creating a close element tag. Here’s a clip from the log:

<Name>This is the Name</Name>
<EmptyString1 />
<EmptyString2 />
<Name2>This is Name2</Name2>

When I get to the foundCharacters method, there are no found characters, and the empty element is being populated by the most recent found characters.

For instance, the string for and is “This is the Name” when I want it to be an empty string or return a string that says “N/A”.

It seems like NSXMLparser doesn’t support this type of end tag, as it is just skipping over it. You would think it would be catchable in didEndElement method, but it never gets there because it doesn’t see it when the slash is at then end instead of .

How can I tell the parser to return a string when it hits this form of end tag?

EDIT: Here is some more from my code. In my understanding, for the most part, I’m already doing what NJones suggests, so I should focus this question more to this situation…

setting the the NSMutableData object to 0 clear it

- (void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response
{
    [webData setLength:0];
}

webData is set from a soap call to the web service and is then put into the log as a string so I can see what the result looks like (same as to NJones “stringToParse” except the soap headers are included) then webData is sent to the parser.

- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data
{
    [webData appendData:data];
    NSString *soapResponse = [[NSString alloc] initWithData:webData encoding:NSASCIIStringEncoding];
    NSLog(@"webData: %@",soapResponse);
}

- (void)connectionDidFinishLoading:(NSURLConnection *)connection
{
    if (xmlParser)
    {
        [xmlParser release];
    }
    xmlParser = [[NSXMLParser alloc] initWithData:webData];
    [xmlParser setDelegate:self];
    [xmlParser setShouldProcessNamespaces:YES];
    [xmlParser parse];

    [connection release];
    [webData release];
}

this inside didStartElement, inside the “File” tag, a.k.a the “WebServiceResult” tag that parses through all the elements

if ([elementName isEqualToString:@"WebServiceResult"]) 
{   
    if(!soapResults)
    {
        soapResults = [[NSMutableString alloc] init]; //declared in .h
    }
    recordResults = YES;
}

below, when I’m in the main parent tag (WebServiceResult), record results is now set to YES, so it goes into foundCharacters and sets the string to @”” then attempts to append

-(void)parser:(NSXMLParser *)parser foundCharacters:(NSMutableString *)string 
{
    if (recordResults)
    {
        if ([string isEqualToString:@""] || string == nil) {
            [soapResults appendString:@"N/A"];
            NSLog(@"foundResults empty: %@",soapResults);
        }
        else {
            [soapResults setString:@""];
           [soapResults appendString: string];
           NSLog(@"foundResults: %@",soapResults);
        }
    }
}

inside the didEndElement method, it is important to note that “EmptyString1” is sometimes NOT EMPTY so you can’t set the EmptyString element to @”” without an if statement of some sort somewhere, like in the foundCharacters method above. Then webData is sent to the parser

-(void)parser:(NSXMLParser *)parser didEndElement:(NSString *)elementName namespaceURI:(NSString *)namespaceURI qualifiedName:(NSString *)qName
{
    if ([elementName isEqualToString:@"Name"]) 
    {
        name = [NSString stringWithFormat:@"%@",soapResults];
        NSLog(@"Name: %@",name);
    }
        if ([elementName isEqualToString:@"EmptyString1"]) 
    {
       sometimesEmptyString = [NSString stringWithFormat:@"%@",soapResults];
       NSLog(@"EmptyString1: %@",sometimesEmptyString);
    }

        //...and the same goes for sometimesEmptyString2, and name2...
}

So in summary, the log is not going into the “foundCharacters empty” if statement with [string isEqualToString:@””] because it never goes into the foundCharacters method when there’s an empty element tag. This is just to clarify, and I’m not sure how to append the @”” if I the parser isn’t seeing the empty element at all…someone will see what I’m missing and I’m sure it’s a simple fix from here

Answer 1

Wow…super easy fix, but I figured it out…

this is the change needed for the foundCharacters method

-(void)parser:(NSXMLParser *)parser foundCharacters:(NSMutableString *)string {

    if (string != nil) {
        [soapResults setString:@""];
        [soapResults appendString: string];
        NSLog(@"foundResults: %@",soapResults);
    }

}

and then I added this simple piece to didEndElement at the very end

[soapMessage setString:@"N/A"];

What this does is set soapMessage to @”N/A” so when foundCharacters is skipped, soapMessage has retained the @”N/A” and if it there’s foundCharacters, it clears the no matter what it is and appends the string to soapMessage so it can be set in didEndElement. So really, the string needs to be set to whatever you want at the end of didEndElement, not in didStartElement for my particualar case.