Construct an xml file from a php array

Combining arrays

First, your problem probably lies in your usage of array_push.

$array = ['test'];
$secondarray = ['foo', 'bar'];

array_push($array, $secondarray);

will give you an $array containing the array $secondarray

Array (
    0 => (string) "test"
    1 => Array (
        0 => (string) "foo"
        1 => (string) "bar"
    )
)

What I guess you want is array_merge(), which will merge the two arrays instead.

$array = ['test'];
$secondArray = ['foo', 'bar'];
$resultArray = array_merge($array, $secondArray);

Which will give you the $resultArray:

Array(
    [1] => (string) "test"
    [2] => (string) "foo"
    [3] => (string) "bar"
)

Converting to XML

You can do this in multiple ways. Write your own solution using XmlWriter or create a DOM structure using either SimpleXml or DomDocument.

SimpleXml

Perhaps the simplest solution is to use SimpleXmlElement like this:

$xml = SimpleXmlElement('<store/>');
$xml->addChild('date', '2017-09-22 19:30');
$products = $xml->addChild('products');
$product  = $products->addChild('product');
foreach ($finCombo as $name => $value) {
    $product->addChild($name, $value);
}
echo $xml->asXML(), PHP_EOL;

SimpleXml with Formatting

If you want to use the same formatting/indentation as in your example, you need to use DomDocument or XmlWriter. If you are already doing this in SimpleXml, you can easily load a DomDocument from a SimpleXmlElement.

...
$domxml = new DOMDocument('1.0');
$domxml->preserveWhiteSpace = false;
$domxml->formatOutput = true;
$domxml->dom_import_simplexml($xml); // load the SimpleXmlElement previously created.
echo $domxml->saveXML();

DomDocument

Or you could do this directly with DOMDocument.

$dom = new DOMDocument('1.0');
$dom->preserveWhiteSpace = false;
$dom->formatOutput = true;
$store = $dom->createElement('store');
$dom->appendChild($store);
$store->appendChild($dom->createElement('date', '2017-09-22 19:30'));
$products = $dom->createElement('products');
$product = $dom->createElement('product');
foreach ($finCombo as $key => $val) {
    $product->appendChild($dom->createElement($key, $val));
}
$products->appendChild($product);
$store->appendChild($products);
echo $dom->saveXML(), PHP_EOL;

XmlWriter

Or, if you want more control (e.g. over indentation), you can use XmlWriter

$writer => new XMLWriter();
$writer->openMemory();
$writer->setIndent(true);
$writer->setIndentString('    ');
$writer->startDocument('1.0', 'UTF-8');
$writer->startElement('store');
$writer->startElement('date');
$writer->text('2017-09-22 19:30');
$writer->fullEndElement(); // end date element
$writer->startElement('products');
$writer->startElement('product');
foreach ($finCombo as $key => $val) {
    $writer->startElement($key);
    $writer->text($val);
    $writer->fullEndElement(); // end $key element
}
$writer->fullEndElement(); // end product element
$writer->fullEndElement(); // end products element
$writer->fullEndElement(); // end store element
$writer->endDocument();
echo $writer->flush(true);