Difference between revisions of "Serialization"

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* Added: {{Code|limit}}: Stops serialization after the specified number of bytes has been serialized

Revision as of 11:14, 4 April 2014

This page is part of the XQuery Portal. Serialization parameters define how XQuery items and XML nodes are textually output, i.e., serialized. (For input, see Parsers.) They have been formalized in the W3C XQuery Serialization 3.0 document. In BaseX, they can be specified by…

  • including them in the prolog of the XQuery expression,
  • specifying them in the XQuery functions file:write() or fn:serialize(). The serialization parameters are specified as
    • children of an <output:serialization-parameters/> element, as defined for the fn:serialize() function, or as
    • map, which contains all key/value pairs: map { "method": "xml", "cdata-section-elements": "div", ... },
  • using the -s flag of the BaseX command-line clients,
  • setting the SERIALIZER option before running a query,
  • setting the EXPORTER option before exporting a database, or
  • setting them as REST query parameters.

Parameters

The following table gives a brief summary of all serialization parameters recognized by BaseX. For details, please refer to official specification.

Parameter Description Allowed Default
method Specifies the serialization method:
  • xml, xhtml, html, and text are adopted from the official specification.
  • json is specific to BaseX and can be used to output XML nodes as JSON objects (see the JSON Module for more details).
  • csv is BaseX-specific and can be used to output XML nodes as CSV data (see the CSV Module for more details).
  • raw is BaseX-specific, too: Binary data types are output in their raw form, i.e., without modifications. For all other types, the items’ string values are returned. No indentation takes place, and and no characters are encoded via entities.
xml, xhtml, html, text, json, csv, raw xml
version Specifies the version of the serialization method. xml/xhtml: 1.0, 1.1
html: 4.0, 4.01, 5.0
1.0
html-version Specifies the version of the HTML serialization method. 4.0, 4.01, 5.0 4.0
item-separator Determines a string to be used as item separator. If a separator is specified, the default separation of atomic values with single whitespaces will be skipped. arbitrary strings, \n, \r\n, \r empty
encoding Encoding to be used for outputting the data. all encodings supported by Java UTF-8
indent Adjusts whitespaces to make the output better readable. yes, no yes
cdata-section-elements List of elements to be output as CDATA, separated by whitespaces.
Example: <text><![CDATA[ <> ]]></text>
omit-xml-declaration Omits the XML declaration, which is serialized before the actual query result
Example: <?xml version="1.0" encoding="UTF-8"?>
yes, no yes
standalone Prints or omits the "standalone" attribute in the XML declaration. yes, no, omit omit
doctype-system Introduces the output with a document type declaration and the given system identifier.
Example: <!DOCTYPE x SYSTEM "entities.dtd">
doctype-public If doctype-system is specified, adds a public identifier.
Example: <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd">
undeclare-prefixes Undeclares prefixes in XML 1.1. yes, no no
normalization-form Specifies a normalization form. BaseX supports Form C (NFC). NFC, none NFC
media-type Specifies the media type. application/xml
use-character-maps Defines character mappings (not supported).
byte-order-mark Prints a byte-order-mark before starting serialization. yes, no no
escape-uri-attributes Escapes URI information in certain HTML attributes
Example: <a href="%C3%A4%C3%B6%C3%BC">äöü<a>
yes, no no
include-content-type Includes a meta content-type element if the result is output as HTML
Example: <head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8"></head>
yes, no no

BaseX provides some additional serialization parameters:

Parameter Description Allowed Default
csv Defines the way how data is serialized as CSV. Version 7.8 see CSV Module
json Defines the way how data is serialized as JSON. Version 7.8 see JSON Module
format Turns output formatting on/off, including the conversion of special characters to entities and insertion of item separators. yes, no yes
tabulator Uses tab characters (\t) instead of spaces for indenting elements. yes, no no
indents Specifies the number of characters to be indented. positive number 2
wrap-prefix,
wrap-uri
Specifies a prefix and/or URI for wrapping the query results.
newline Specifies the type of newline to be used as end-of-line marker. \n, \r\n, \r system dependent
limit Stops serialization after the specified number of bytes has been serialized. If a negative number is specified, everything will be output. Version 7.8.2 positive number -1

The csv and json parameters are supplied with a list of options. Option names and values are combined with =, several options are separated by ,:

Query:

declare option output:method "csv";
declare option output:csv "header=yes, separator=semicolon";
<csv>
  <record>
    <Name>John</Name>
    <City>Newton</City>
  </record>
  <record>
    <Name>Jack</Name>
    <City>Oldtown</City>
  </record>
</csv>

Result:

Name;City
John;Newton
Jack;Oldtown

Changelog

Version 7.8.2
  • Added: limit: Stops serialization after the specified number of bytes has been serialized
Version 7.8
  • Added: csv and json serialization parameters
  • Removed: separator option (use item-separator instead)
Version 7.7.2
  • Added: csv serialization method
  • Added: temporary serialization methods csv-header, csv-separator, json-unescape, json-spec, json-format
Version 7.5
  • Added: official item-separator and html-version parameter
  • Updated: method=html5 removed; serializers updated with the latest version of the specification, using method=html and version=5.0.
Version 7.2
  • Added: separator parameter
Version 7.1
  • Added: newline parameter
Version 7.0
  • Added: Serialization parameters added to REST API; JSON/JsonML/raw methods