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I'm parsing a document for several different values, with PHP and Xpath. I'm throwing the results/matches of my Xpath queries into an array. So for example, I build my $prices array like this:

$prices = array();
$result = $xpath->query("//div[@class='the-price']");
foreach ($result as $object) {
$prices[] = $object->nodeValue; }

Once I have my array built, I loop through and throw the values into some HTML like this:

$i = 0;
foreach ($links as $link) {
    echo <<<EOF
<div class="the-product">
    <div class="the-name"><a title="{$names[$i]}" href="{$link}" target="blank">{$names[$i]}</a></div>
    <br />
    <div class="the-image"><a title="{$names[$i]}" href="{$link}" target="blank"><img src="{$images[$i]}" /></a></div>
    <br />
    <div class="the-current-price">Price is: <br> {$prices[$i]}</div>
</div>
EOF;
    $i++; }

The problem is, some items in the original document that I'm parsing don't have a price, as in, they don't even contain <div class='the-price'>, so my Xpath isn't finding a value, and isn't inserting a value into the $prices array. I end up returning 20 products, and an array which contains only 17 keys/values, leading to Notice: Undefined offset errors all over the place.

So my question is, how can I account for items that are missing key values and throwing off my arrays? Can I insert dummy values into the array for these items? I've tried as many different solutions as I can think of. Mainly, IF statements within my foreach loops, but nothing seems to work.

Thank you

share|improve this question
    
Presumably in your 17/20 scenario, its the last 3 which are empty so making most of the previous ones show incorrect prices, is this the case? –  Cups Jul 16 '12 at 19:48
    
In that scenario, yes that is the case. But there could be any scenario with X out of 20 products have a missing price. And these products could be anywhere within the loop. –  rocky Jul 16 '12 at 20:56

4 Answers 4

up vote 0 down vote

I suggest you look for an element inside your html which is always present in your "price"-loop. After you find this object you start looking for the "price" element, if there is none, you insert an empty string, etc. into your array.

share|improve this answer
up vote 0 down vote

Instead of directly looking for the the-price elements, look for the containing the-product. Loop on those, then do a subquery using those nodes as the starting context. That way you get all of the the-product nodes, plus the prices for those that have them.

e.g.

$products = array();
$products = $xpath->query("//div[@class='the-product']");
$found = 0 ;
foreach ($products as $product) {
   $products[$found] = array();
   $price = $xpath->query("//div[@class='the-price']", $product);
   if ($price->length > 0) {
       $products[$found] = $price->item(0)->nodeValue;
   }
   $found++;
}
share|improve this answer
    
Thanks Marc. Unfortunately this is returning a fatal error for me - 'Cannot use object of type DOMNodeList as array' –  rocky Jul 16 '12 at 23:07
    
Oops. misused $products in there as the final array and the results of the query. –  Marc B Jul 17 '12 at 4:50
up vote 0 down vote

If you don't want to show the products that don't have a price attached to them you could check if $prices[$i] is set first.

foreach($links AS $link){
    if(isset($prices[$i])){
        // echo content
    }
}

Or if you wanted to fill it will dummy values you could say

$prices = array_merge($prices,
              array_fill(count($prices), count($links)-count($prices),0));

And that would insert 0 as a dummy value for any remaining values. array_fill starts off by taking the first index of the array (so we start one after the amount of keys in $prices), then how many we need to fill, so we subtract how many are in $prices from how many are in $links, then we fill it with the dummy value 0.

Alternatively you could use the same logic in the first example and just apply that by saying:

echo isset($prices[$i]) ? $prices[$i] : '0';
share|improve this answer
    
Thanks Marcus. I DO still want to show products with missing prices, and ideally, represent them with a dummy value, within my $prices array. Your last block of code seems to work, but it appears to just marge the dummy '0' values at the end of the array. –  rocky Jul 16 '12 at 23:19
up vote 0 down vote

Hard to understand the relation between $links and $prices with the code shown. Since you are building the $prices array without any relation to the $links array, I don't see how you would do this.

Is $links also built via xpath? If so, is 'the-price' div always nested within the DOM element used to populate $links?

If it is you could nest your xpath query to find the price within the query used to find the links and use a counter to match the two.

i.e.

$links_result = $xpath->query('path-to-link')
$i = 0
foreach ($links_result as $link_object) {
    $links[$i] = $link_object->nodeValue;
    // pass $link_object as context reference to xpath query looking for price
    $price_result = $xpath->query('path-to-price-within-link-node', $link_object);
    if (false !== $price_result) {
        $prices[$i] = $price_result->nodeValue;
    } else {
        $prices[$i] = 0; // or whatever value you want to show to indicate that no price was available.
    }
    $i++;
}

Obviously, there could be additional handling in there to verify that only one price value exists per link node and so forth, but that is basic idea.

share|improve this answer
    
Hey Mike, thanks for the answer. $links IS also built via Xpath. But 'the-price' div is NOT always nested within that same DOM element. For the products that are missing prices, that div simply doesn't exist. –  rocky Jul 16 '12 at 23:09
    
That is fine if they are alwasy nested if present, this code should work. If the 'the-price' div does not exist, the $price_result value reutrned from the xpath query will be false, in which cases you know to simply add a $prices[$i] = 0 or whatever value you want to add to indicate there is no price for the item. –  Mike Brant Jul 17 '12 at 13:57
    
Thanks Mike... going to give this a shot. –  rocky Jul 24 '12 at 20:11

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