xml_stream_reader_task.md

XmlStreamReaderTask

Reads an XML file element by element with XMLReader and iterates over the elements with a given name, outputting each of them as a \DOMElement. Unlike XmlReaderTask, the whole file is never loaded in memory: use it for large XML files (product catalogs, ERP exports...). Requires the dom and xmlreader PHP extensions.

Task reference

• Service: CleverAge\ProcessBundle\Task\File\Xml\XmlStreamReaderTask
• Iterable task

Accepted inputs

string: path of the file to read, only used when the file_path option is not set (ignored otherwise).

Possible outputs

\DOMElement: for each element named node_name, the element expanded with XMLReader::expand, as the root element of its own \DOMDocument. It can be passed directly to the XpathEvaluatorTransformer, with queries relative to the element (e.g. @id, name/text()).

When the file contains no matching element, no output is produced and the task is skipped.

Options

Code	Type	Required	Default	Description
file_path	string|null		null	Path of the file to read. When null, the path is read from the input
node_name	string	X		Qualified name of the elements to iterate on, as written in the file (e.g. product, or g:item for an element with a prefix)

Examples

# Task configuration level
read:
  service: '@CleverAge\ProcessBundle\Task\File\Xml\XmlStreamReaderTask'
  options:
    file_path: '%kernel.project_dir%/var/data/products.xml'
    node_name: product
  outputs: [transform]
transform:
  service: '@CleverAge\ProcessBundle\Task\TransformerTask'
  options:
    transformers:
      xpath_evaluator:
        query:
          sku: '@sku'
          name: 'name/text()'
  outputs: [write]

Notes

• Elements are matched at any depth. The subtree of a matching element is not searched again: an element named node_name nested inside a matching element is part of its parent output, and is not output on its own.
• Namespaces declared on ancestors are copied to the expanded element, so prefixed queries (e.g. g:price/text()) still work.
• An invalid XML content (not well-formed, empty file...) throws an \UnexpectedValueException whose message contains the libxml error(s) with their line and column, handled by the task error_strategy. As the file is read as a stream, the elements located before the error have already been output. libxml warnings are tolerated.
• A missing or unreadable file, or no file path in the option nor in the input, throws an \UnexpectedValueException.
• The file is released at the end of the iteration (and on finalize()), so that the task can read it again on its next input.
• Use XmlReaderTask to get the whole document at once (small files).