XmlStreamDataset

XmlStreamDataset reads an XML file one row element at a time: only the element being read is in memory, not the whole document, as XmlDataset loads it. Use it for a large file.

It uses XmlBlockReader of byjg/serializer (XMLReader): entities are never expanded and nothing is fetched from the network.

Basic Usage

<?php
$dataset = new \ByJG\AnyDataset\Xml\XmlStreamDataset(
    "/data/books.xml",
    "book",
    [
        "category" => "@category",
        "title" => "title",
        "lang" => "title/@lang",
    ]
);

foreach ($dataset->getIterator() as $row) {
    echo $row->get("title");
}

Constructor Parameters

public function __construct(
    string $filename,
    string $rowElement,
    array $colNodes,
    array $registerNS = []
)

• $filename - the XML file
• $rowElement - the name of the row elements, at any depth (not an XPath: no path, no predicate)
• $colNodes - the columns, as in XmlDataset: an XPath relative to the row element, or a callable that receives the row
• $registerNS - the namespace URI of each prefix used in $rowElement and $colNodes

Namespaces

With a prefix of $registerNS, $rowElement is the elements of that namespace, whatever prefix the file uses (none, for a default namespace):

<?php
// <feed xmlns="http://www.w3.org/2005/Atom" xmlns:gd="http://schemas.google.com/g/2005"><entry>...
$dataset = new \ByJG\AnyDataset\Xml\XmlStreamDataset(
    "/data/contacts.xml",
    "atom:entry",
    [
        "id" => "atom:id",
        "name" => "atom:title",
        "email" => "gd:email/@address",
    ],
    [
        "atom" => "http://www.w3.org/2005/Atom",
        "gd" => "http://schemas.google.com/g/2005",
    ]
);

Without a prefix of $registerNS, the name is compared as written in the file (entry, or atom:entry when the file uses that prefix).

Compared with XmlDataset

	XmlDataset	XmlStreamDataset
Input	string, DOMDocument, XmlNode or File	a file
Rows	any XPath	an element name, at any depth
A row element inside a row	another row	part of the row
Columns	XPath or callable	the same
Memory	the whole document	one row element

Iterating

getIterator() reads the file again on each call. The iterator moves forward only, and the file is closed when the rows end or the iterator is dropped (first(), a foreach with break). An invalid XML throws ByJG\Serializer\Exception\InvalidArgumentException while the rows are read: the rows before the error may already have been processed.