How to loop through two XML files and print result - php

Question

I've been trying unsuccessfully with PHP to loop through two XML files and print the result to the screen. The aim is to take a country's name and output its regions/states/provinces as the case may be.
The first block of code successfully prints all the countries but the loop through both files gives me a blank screen.
The countries file is in the format:
<row>
<id>6</id>
<name>Andorra</name>
<iso2>AD</iso2>
<phone_code>376</phone_code>
</row>
And the states.xml:
<row>
<id>488</id>
<name>Andorra la Vella</name>
<country_id>6</country_id>
<country_code>AD</country_code>
<state_code>07</state_code>
</row>
so that country_id = id.
This gives a perfect list of countries:
$xml = simplexml_load_file("countries.xml");
$xml1 = simplexml_load_file("states.xml");
foreach($xml->children() as $key => $children) {
print((string)$children->name); echo "<br>";
}
This gives me a blank screen except for the HTML stuff on the page:
$xml = simplexml_load_file("countries.xml");
$xml1 = simplexml_load_file("states.xml");
$s = "Jamaica";
foreach($xml->children() as $child) {
foreach($xml1->children() as $child2){
if ($child->id == $child2->country_id && $child->name == $s) {
print((string)$child2->name);
echo "<br>";
}
}
}
Where have I gone wrong?
Thanks.

Answer 1

I suspect your problem is not casting the name to a string before doing your comparison. But why are you starting the second loop before checking if it's needed? You're looping through every single item in states.xml needlessly.
$countries = simplexml_load_file("countries.xml");
$states = simplexml_load_file("states.xml");
$search = "Jamaica";
foreach($countries->children() as $country) {
if ((string)$country->name !== $search) {
continue;
}
foreach($states->children() as $state) {
if ((string)$country->id === (string)$state->country_id) {
echo (string)$state->name . "<br/>";
}
}
}
Also, note that naming your variables in a descriptive manner makes it much easier to figure out what's going on with code.
You could probably get rid of the loops altogether using an XPath query to match the sibling value. I don't use SimpleXML, but here's what it would look like with DomDocument:
$search = "Jamaica";
$countries = new DomDocument();
$countries->load("countries.xml");
$xpath = new DomXPath($countries);
$country = $xpath->query("//row[name/text() = '$search']/id/text()");
$country_id = $country[0]->nodeValue;
$states = new DomDocument();
$states->load("states.xml");
$xpath = new DomXPath($states);
$states = $xpath->query("//row[country_id/text() = '$country_id']/name/text()");
foreach ($states as $state) {
echo $state->nodeValue . "<br/>";
}