Node no longer exists using if (isset) on an array in PHP - php

Question

Is it possible to use an if isset on an item in an array?
example:
if (isset($cityWeatherRssUrls[0])
I receive the following warning when doing so.
Warning: get_temperature() [function.get-temperature]: Node no longer exists in C:\xampp\htdocs\Twinz\includes\getWeather.php on line 51
Line 51 begins after the //Pull temperature comment from the function get_temperature(SimpleXMLElement $xml) in my getWeather.php script.
Below contains all the relevant scripts and functions
cityConfig.php - is used for declaring all the cities and corresponding URL's to yahoo's weather XML.
// Define arrays //
$cities = array();
$cityWeatherRssUrls = array();
// Feed URL's //
$yahooWeather = 'http://weather.yahooapis.com/forecastrss?p=';
// City 1 //
$city = 'London';
$cityWeatherRssUrl = $yahooWeather . $cityWeatherFeedCode . '&u=c';
array_push($cities, $city);
array_push($cityWeatherRssUrls, $cityWeatherRssUrl);
getWeather.php - contains functions for parsing XML tag contents and displaying the content
function get_current_weather($weatherRssUrl) {
// Get XML data from source
if (isset($weatherRssUrl)) {
$feed = $weatherRssUrl;
} else {
echo 'Feed not found. Check URL';
}
checkFeedExists($feed);
$xml = new SimpleXmlElement($feed);
$weather = get_temperature($xml);
return $weather;
}
function get_temperature(SimpleXMLElement $xml) {
// Pull temperature from XML
$weather['temp'] = $xml->channel->item->children('yweather', TRUE)->condition->attributes()->temp;
echo round($weather['temp']) . "°C" . "<br />";
return $temp;
}
//Display City Content //
function displayCityContent($cityWeatherRssUrls, $columnSubheading) {
if (isset($cityWeatherRssUrls)) {
echo get_current_weather($cityWeatherRssUrls);
echo $columnSubheading;
echo get_forecast_weather($cityWeatherRssUrls);
echo '<br />';
} else {
content_unavailable();
}
}
threeColumnContainer.php - is used to display Weather contents inside a html column
<ul class="columns">
<li class="col1">
<h3><?php
if (isset($column1Heading)) {
echo $column1Heading;
}
?></h3>
<p>
<?php
if (isset($cityWeatherRssUrls[0]) && ($currentPage == 1)) {
echo displayCityContent($cityWeatherRssUrls[0], $columnSubheading);
I can confirm that $cityWeatherRssUrls[0] contains the weather url for London because if I increment the array $cityWeatherRssUrls[1] I receive the a message saying that the feed cannot be found.
Any thoughts?
Thanks in advance

Answer 1

There were quite a few key concepts missing from your code, but hopefully the following will help you fix your code...
<?php
function get_feed($feed_url)
{
$ch = curl_init();
curl_setopt($ch, CURLOPT_URL, $feed_url);
curl_setopt($ch, CURLOPT_FRESH_CONNECT, 1);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
$rss = curl_exec($ch);
curl_close($ch);
return $rss;
}
function get_weather_feed_xml($feed_url = null)
{
$feed = get_feed($feed_url);
return new SimpleXmlElement($feed);
}
function get_temperature($feed_url)
{
if(stripos($feed_url, 'yahooapis') !== false)
{
return get_temperature_yahoo($feed_url);
}
return false;
}
function get_temperature_yahoo($feed_url)
{
if(($xml = get_weather_feed_xml($feed_url)) !== false)
{
return (float)$xml->channel->item->children('yweather', true)->condition->attributes()->temp;
}
return false;
}
function get_city_temperature($city_name, $city_WOEID, $feeds)
{
$results = array();
foreach($feeds as $feed_name => $feed_url)
{
$feed_url = str_replace(array('{WOEID}', '{NAME}'), array($city_WOEID, $city_name), $feed_url);
$results[$feed_name] = get_temperature($feed_url);
}
return $results;
}
function get_cities_temperature($cities, $feeds)
{
$results = array();
foreach($cities as $city_name => $city_WOEID)
{
$results[$city_name] = get_city_temperature($city_name, $city_WOEID, $feeds);
}
return $results;
}
// -------------------------------
$cities = array(
'London' => 44418,
'Los Angeles' => 2442047,
'Sydney' => 1105779,
);
$feeds = array(
'Yahoo' => 'http://weather.yahooapis.com/forecastrss?u=c&w={WOEID}',
);
$check = get_cities_temperature($cities, $feeds);
echo '<pre>';
print_r($check);
echo '</pre>';