Difference between revisions of "Fetch Module"
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| '''Summary''' | | '''Summary''' | ||
− | |Fetches the resource referred to by the given URI and returns it as [[ | + | |Fetches the resource referred to by the given URI and returns it as [[Lazy Module|lazy]] {{Code|xs:base64Binary}}. |
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| '''Errors''' | | '''Errors''' | ||
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* <code><nowiki>fetch:binary("http://images.trulia.com/blogimg/c/5/f/4/679932_1298401950553_o.jpg")</nowiki></code> returns the addressed image. | * <code><nowiki>fetch:binary("http://images.trulia.com/blogimg/c/5/f/4/679932_1298401950553_o.jpg")</nowiki></code> returns the addressed image. | ||
− | * <code><nowiki> | + | * <code><nowiki>lazy:cache(fetch:binary("http://en.wikipedia.org"))</nowiki></code> enforces the fetch operation (otherwise, it will be delayed until requested first). |
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| '''Summary''' | | '''Summary''' | ||
− | |Fetches the resource referred to by the given {{Code|$uri}} and returns it as [[ | + | |Fetches the resource referred to by the given {{Code|$uri}} and returns it as [[Lazy Module|lazy]] {{Code|xs:string}}: |
* The UTF-8 default encoding can be overwritten with the optional {{Code|$encoding}} argument. | * The UTF-8 default encoding can be overwritten with the optional {{Code|$encoding}} argument. | ||
* By default, invalid characters will be rejected. If {{Code|$fallback}} is set to true, these characters will be replaced with the Unicode replacement character <code>FFFD</code> (�). | * By default, invalid characters will be rejected. If {{Code|$fallback}} is set to true, these characters will be replaced with the Unicode replacement character <code>FFFD</code> (�). | ||
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* <code><nowiki>fetch:text("http://en.wikipedia.org")</nowiki></code> returns a string representation of the English Wikipedia main HTML page. | * <code><nowiki>fetch:text("http://en.wikipedia.org")</nowiki></code> returns a string representation of the English Wikipedia main HTML page. | ||
* <code><nowiki>fetch:text("http://www.bbc.com","US-ASCII",true())</nowiki></code> returns the BBC homepage in US-ASCII with all non-US-ASCII characters replaced with �. | * <code><nowiki>fetch:text("http://www.bbc.com","US-ASCII",true())</nowiki></code> returns the BBC homepage in US-ASCII with all non-US-ASCII characters replaced with �. | ||
− | * <code><nowiki> | + | * <code><nowiki>lazy:cache(fetch:text("http://en.wikipedia.org"))</nowiki></code> enforces the fetch operation (otherwise, it will be delayed until requested first). |
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Revision as of 13:18, 15 March 2018
This XQuery Module provides simple functions to fetch the content of resources identified by URIs. Resources can be stored locally or remotely and e.g. use the file://
or http://
scheme. If more control over HTTP requests is required, the HTTP Module can be used. With the HTML Module, retrieved HTML documents can be converted to XML.
Contents
Conventions
All functions and errors in this module are assigned to the http://basex.org/modules/fetch
namespace, which is statically bound to the fetch
prefix.
URI arguments can point be URLs or point to local files. Relative file paths will be resolved against the current working directory (for more details, have a look at the File Module).
Functions
fetch:binary
Signatures | fetch:binary($uri as xs:string) as xs:base64Binary |
Summary | Fetches the resource referred to by the given URI and returns it as lazy xs:base64Binary .
|
Errors | open : the URI could not be resolved, or the resource could not be retrieved.
|
Examples |
|
fetch:text
Signatures | fetch:text($uri as xs:string) as xs:string fetch:text($uri as xs:string, $encoding as xs:string) as xs:string fetch:text($uri as xs:string, $encoding as xs:string, $fallback as xs:boolean) as xs:string |
Summary | Fetches the resource referred to by the given $uri and returns it as lazy xs:string :
|
Errors | open : the URI could not be resolved, or the resource could not be retrieved.encoding : the specified encoding is not supported, or unknown.
|
Examples |
|
fetch:xml
Signatures | fetch:xml($uri as xs:string) as document-node() fetch:xml($uri as xs:string, $options as map(*)?) as document-node()
|
Summary | Fetches the resource referred to by the given $uri and returns it as XML document node.In contrast to fn:doc , each function call returns a different document node. As a consequence, document instances created by this function will not be kept in memory until the end of query evaluation.The $options argument can be used to change the parsing behavior. Allowed options are all parsing and XML parsing options in lower case.
|
Errors | open : the URI could not be resolved, or the resource could not be retrieved.
|
Examples |
fetch:xml("http://en.wikipedia.org", map { 'chop': true() })
fetch:xml(file:base-dir() || "example.xml") |
fetch:xml-binary
Signatures | fetch:xml-binary($data as xs:base64Binary) as document-node() fetch:xml-binary($data as xs:base64Binary, $options as map(*)?) as document-node()
|
Summary | Parses binary $data and returns it as XML document node.In contrast to fn:parse-xml, which expects an XQuery string, the input of this function can be arbitrarily encoded. The encoding will be derived from the XML declaration or (in case of UTF16 or UTF32) from the first bytes of the input. The $options argument can be used to change the parsing behavior. Allowed options are all parsing and XML parsing options in lower case.
|
Examples |
fetch:xml-binary(file:read-binary('doc.xml'))
fetch:xml-binary(convert:string-to-base64( "<?xml version='1.0' encoding='CP1252'?><xml>touché</xml>", "CP1252" ))
fetch:xml-binary(convert:string-to-base64("<xml/>", "UTF16")) |
fetch:content-type
Signatures | fetch:content-type($uri as xs:string) as xs:string |
Summary | Returns the content-type (also called mime-type) of the resource specified by $uri :
|
Errors | open : the URI could not be resolved, or the resource could not be retrieved.
|
Examples |
|
Errors
Code | Description |
---|---|
encoding
|
The specified encoding is not supported, or unknown. |
open
|
The URI could not be resolved, or the resource could not be retrieved. |
Changelog
- Version 9.0
- Added: fetch:xml-binary
- Updated: error codes updated; errors now use the module namespace
- Version 8.5
- Updated: fetch:text:
$fallback
argument added.
- Version 8.0
- Added: fetch:xml
The module was introduced with Version 7.6.