Difference between revisions of "Full-Text Module"

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m (Text replacement - "[http://www.w3.org/TR/xpath" to "[https://www.w3.org/TR/xpath")
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This [[Module Library|XQuery Module]] extends the [http://www.w3.org/TR/xpath-full-text-10 W3C Full Text Recommendation] with some useful functions: The index can be directly accessed, full-text results can be marked with additional elements, or the relevant parts can be extracted. Moreover, the score value, which is generated by the {{Code|contains text}} expression, can be explicitly requested from items.
+
This [[Module Library|XQuery Module]] extends the [https://www.w3.org/TR/xpath-full-text-10 W3C Full Text Recommendation] with some useful functions: The index can be directly accessed, fulltext results can be marked with additional elements, or the relevant parts can be extracted. Moreover, the score value, which is generated by the {{Code|contains text}} expression, can be explicitly requested from items.
  
 
=Conventions=
 
=Conventions=
  
All functions in this module are assigned to the {{Code|http://basex.org/modules/ft}} namespace, which is statically bound to the {{Code|ft}} prefix.<br/>
+
All functions and errors in this module are assigned to the <code><nowiki>http://basex.org/modules/ft</nowiki></code> namespace, which is statically bound to the {{Code|ft}} prefix.<br/>
All errors are assigned to the {{Code|http://basex.org/errors}} namespace, which is statically bound to the {{Code|bxerr}} prefix.
 
  
 
=Functions=
 
=Functions=
Line 10: Line 9:
 
==ft:search==
 
==ft:search==
  
{{Mark|Updated with Version 7.3:}} second argument generalized, third parameter added.
+
{| width='100%'
 
 
{|
 
 
|-
 
|-
| width='90' | '''Signatures'''
+
| width='120' | '''Signatures'''
|{{Func|ft:search|$db as item(), $terms as item()*|text()*}}<br/>{{Func|ft:search|$db as item(), $terms as item()*, $options as item()|text()*}}
+
|{{Func|ft:search|$db as xs:string, $terms as item()*|text()*}}<br/>{{Func|ft:search|$db as xs:string, $terms as item()*, $options as map(*)?|text()*}}
 
|-
 
|-
 
| '''Summary'''
 
| '''Summary'''
|Returns all text nodes from the full-text index of the [[Database Module#Database Nodes|database node]] {{Code|$db}} that contain the specified {{Code|$terms}}.<br/>The options used for building the full-text will also be applied to the search terms. As an example, if the index terms have been stemmed, the search string will be stemmed as well.
+
|Returns all text nodes from the full-text index of the database {{Code|$db}} that contain the specified {{Code|$terms}}.<br/>The options used for tokenizing the input and building the full-text will also be applied to the search terms. As an example, if the index terms have been stemmed, the search string will be stemmed as well.
The {{Code|$options}} argument can be used to overwrite the default full-text options. It can be specified as
+
The {{Code|$options}} argument can be used to control full-text processing. The following options are supported (the introduction on [[Full-Text]] processing gives you equivalent expressions in the XQuery Full-Text notation):
* {{Code|element(options)}}: {{Code|&lt;options/&gt;}} must be used as root element, and the parameters are specified as child nodes, with the element name representing the key and the text node representing the value:<br />
+
* {{Code|mode}}: determines the mode how tokens are searched. Allowed values are {{Code|any}}, {{Code|any word}}, {{Code|all}}, {{Code|all words}}, and {{Code|phrase}}. {{Code|any}} is the default search mode.
<pre class="brush:xml">
+
* {{Code|fuzzy}}: turns fuzzy querying on or off. Allowed values are {{Code|true}} and {{Code|false}}. By default, fuzzy querying is turned off.
<options>
+
* {{Code|wildcards}}: turns wildcard querying on or off. Allowed values are {{Code|true}} and {{Code|false}}. By default, wildcard querying is turned off.
  <key>value</key>
+
* {{Code|ordered}}: requires that all tokens occur in the order in which they are specified. Allowed values are {{Code|true}} and {{Code|false}}. The default is {{Code|false}}.
  ...
+
* {{Code|content}}: specifies that the matched tokens need to occur at the beginning or end of a searched string, or need to cover the entire string. Allowed values are {{Code|start}}, {{Code|end}}, and {{Code|entire}}. By default, the option is turned off.
</options>
+
* {{Code|scope}}: defines the scope in which tokens must be located. The option has following sub options:
</pre>
+
** {{Code|same}}: can be set to {{Code|true}} or {{Code|false}}. It specifies if tokens need to occur in the same or different units.
* [[Map Module|map structure]]: all parameters can be directly represented as key/value pairs:<br /><code>map { "key" := "value", ... }</code><br/>This variant is more compact, but please note that the W3C’s specification of maps in XQuery is still work in progress.
+
** {{Code|unit}}: can be {{Code|sentence}} or {{Code|paragraph}}. It specifies the unit for finding tokens.
The following keys are supported:
+
* {{Code|window}}: sets up a window in which all tokens must be located. By default, the option is turned off. It has following sub options:
* {{Code|mode}}: determines the search mode (also called [http://www.w3.org/TR/xpath-full-text-10/#ftwords AnyAllOption]). Allowed values are {{Code|any}}, {{Code|any word}}, {{Code|all}}, {{Code|all words}}, and {{Code|phrase}}. {{Code|any}} is the default search mode.
+
** {{Code|size}}: specifies the size of the window in terms of ''units''.
* {{Code|fuzzy}}: turns fuzzy querying on or off. Allowed values are an empty string or {{Code|true}}, or {{Code|false}}. By default, fuzzy querying is turned off.
+
** {{Code|unit}}: can be {{Code|sentences}}, {{Code|sentences}} or {{Code|paragraphs}}. The default is {{Code|words}}.
* {{Code|wildcards}}: turns wildcard querying on or off. Allowed values are an empty string or {{Code|true}}, or {{Code|false}}. By default, wildcard querying is turned off.
+
* {{Code|distance}}: specifies the distance in which tokens must occur. By default, the option is turned off. It has following sub options:
 +
** {{Code|min}}: specifies the minimum distance in terms of ''units''. The default is {{Code|0}}.
 +
** {{Code|max}}: specifies the maximum distance in terms of ''units''. The default is {{Code|∞}}.
 +
** {{Code|unit}}: can be {{Code|words}}, {{Code|sentences}} or {{Code|paragraphs}}. The default is {{Code|words}}.
 
|-
 
|-
 
| '''Errors'''
 
| '''Errors'''
|{{Error|BXDB0004|Database Module#Errors}} the full-text index is not available.<br/>{{Error|BXFT0001|#Errors}} both fuzzy and wildcard querying was selected.
+
|{{Error|db:open|Database Module#Errors}} The addressed database does not exist or could not be opened.<br/>{{Error|db:no-index|Database Module#Errors}} the index is not available.<br/>{{Error|options|#Errors}} the fuzzy and wildcard option cannot be both specified.
 
|-
 
|-
 
| '''Examples'''
 
| '''Examples'''
 
|
 
|
* {{Code|ft:search("DB", "QUERY")}} returns all text nodes of the database {{Code|DB}} that contain the term {{Code|QUERY}}.
+
* {{Code|ft:search("DB", "QUERY")}}: Return all text nodes of the database {{Code|DB}} that contain the term {{Code|QUERY}}.
* <code>ft:search("DB", (2010,2011), map { 'mode':='all' })</code><br/>returns all text nodes of the database {{Code|DB}} that contain the numbers {{Code|2010}} and {{Code|20111}}.
+
* Return all text nodes of the database {{Code|DB}} that contain the numbers {{Code|2010}} and {{Code|2020}}:<br/><code>ft:search("DB", ("2010", "2020"), map { 'mode': 'all' })</code>
* The last example iterates over five databases and returns all elements containing terms similar to {{Code|Hello World}} in the text nodes:
+
* Return text nodes that contain the terms {{Code|A}} and {{Code|B|}} in a distance of at most 5 words:
<pre class="brush:xquery">
+
<syntaxhighlight lang="xquery">
 +
ft:search("db", ("A", "B"), map {
 +
  "mode": "all words",
 +
  "distance": map {
 +
    "max": "5",
 +
    "unit": "words"
 +
  }
 +
})
 +
</syntaxhighlight>
 +
* Iterate over three databases and return all elements containing terms similar to {{Code|Hello World}} in the text nodes:
 +
<syntaxhighlight lang="xquery">
 
let $terms := "Hello Worlds"
 
let $terms := "Hello Worlds"
 
let $fuzzy := true()
 
let $fuzzy := true()
let $options :=
 
  <options>
 
    <fuzzy>{ $fuzzy }</fuzzy>
 
  </options>
 
 
for $db in 1 to 3
 
for $db in 1 to 3
 
let $dbname := 'DB' || $db
 
let $dbname := 'DB' || $db
return ft:search($dbname, $terms, $options)/..
+
return ft:search($dbname, $terms, map { 'fuzzy': $fuzzy })/..
</pre>
+
</syntaxhighlight>
 +
|}
 +
 
 +
==ft:contains==
 +
 
 +
{| width='100%'
 +
|-
 +
| width='120' | '''Signatures'''
 +
|{{Func|ft:contains|$input as item()*, $terms as item()*|xs:boolean}}<br/>{{Func|ft:contains|$input as item()*, $terms as item()*, $options as map(*)?|xs:boolean}}
 +
|-
 +
| '''Summary'''
 +
|Checks if the specified {{Code|$input}} items contain the specified {{Code|$terms}}.<br/>The function does the same as the [[Full-Text]] expression {{Code|contains text}}, but options can be specified more dynamically. The {{Code|$options}} are the same as for [[#ft:search|ft:search]], and the following ones in addition:
 +
* {{Code|case}}: determines how character case is processed. Allowed values are {{Code|insensitive}}, {{Code|sensitive}}, {{Code|upper}} and {{Code|lower}}. By default, search is case insensitive.
 +
* {{Code|diacritics}}: determines how diacritical characters are processed. Allowed values are {{Code|insensitive}} and {{Code|sensitive}}. By default, search is diacritical insensitive.
 +
* {{Code|stemming}}: determines is tokens are stemmed. Allowed values are {{Code|true}} and {{Code|false}}. By default, stemming is turned off.
 +
* {{Code|language}}: determines the language. This option is relevant for stemming tokens. All language codes are supported. The default language is {{Code|en}}.
 +
|-
 +
| '''Errors'''
 +
|{{Error|options|#Errors}} specified options are conflicting.
 +
|-
 +
| '''Examples'''
 +
|
 +
* Checks if {{Code|jack}} or {{Code|john}} occurs in the input string {{Code|John Doe}}:
 +
<syntaxhighlight lang="xquery">
 +
ft:contains("John Doe", ("jack", "john"), map { "mode": "any" })
 +
</syntaxhighlight>
 +
* Calls the function with stemming turned on and off:
 +
<syntaxhighlight lang="xquery">
 +
(true(), false()) ! ft:contains("Häuser", "Haus", map { 'stemming': ., 'language':'de' })
 +
</syntaxhighlight>
 
|}
 
|}
  
 
==ft:mark==
 
==ft:mark==
{|
+
 
 +
{| width='100%'
 
|-
 
|-
| width='90' | '''Signatures'''
+
| width='120' | '''Signatures'''
|{{Func|ft:mark|$nodes as node()*|node()*}}<br />{{Func|ft:mark|$nodes as node()*, $tag as xs:string|node()*}}
+
|{{Func|ft:mark|$nodes as node()*|node()*}}<br />{{Func|ft:mark|$nodes as node()*, $name as xs:string|node()*}}
 
|-
 
|-
 
| '''Summary'''
 
| '''Summary'''
|Puts a marker element around the resulting {{Code|$nodes}} of a full-text index request.<br />The default tag name of the marker element is {{Code|mark}}. An alternative tag name can be chosen via the optional {{Code|$tag}} argument.<br />Note that the XML node to be transformed must be an internal "database" node. The {{Code|transform}} expression can be used to apply the method to a main-memory fragment (see example).
+
|Puts a marker element around the resulting {{Code|$nodes}} of a full-text request.<br />The default name of the marker element is {{Code|mark}}. An alternative name can be chosen via the optional {{Code|$name}} argument.<br />Please note that:
 +
* The full-text expression that computes the token positions must be specified as argument of the <code>ft:mark()</code> function, as all position information is lost in subsequent processing steps. You may need to specify more than one full-text expression if you want to use the function in a FLWOR expression, as shown in Example 2.
 +
* The supplied node must be a [[Database Module#Database Node|Database Node]]. As shown in Example 3, {{Code|update}} or {{Code|transform}} can be utilized to convert a fragment to the required internal representation.
 
|-
 
|-
 
| '''Examples'''
 
| '''Examples'''
|
+
|'''Example 1''': The following query returns {{Code|&lt;XML&gt;&lt;mark&gt;hello&lt;/mark&gt; world&lt;/XML&gt;}}, if one text node of the database {{Code|DB}} has the value "hello world":
* The following query returns {{Code|&lt;XML&gt;&lt;mark&gt;hello&lt;/mark&gt; world&lt;/XML&gt;}}, if one text node of the database {{Code|DB}} has the value "hello world":
+
<syntaxhighlight lang="xquery">
<pre class="brush:xquery">
 
 
ft:mark(db:open('DB')//*[text() contains text 'hello'])
 
ft:mark(db:open('DB')//*[text() contains text 'hello'])
</pre>
+
</syntaxhighlight>
* The following expression returns {{Code|&lt;p&gt;&lt;b&gt;word&lt;/b&gt;&lt;/p&gt;}}:
+
'''Example 2''': The following expression loops through the first ten full-text results and marks the results in a second expression:
<pre class="brush:xquery">
+
<syntaxhighlight lang="xquery">
copy $p := &lt;p&gt;word&lt;/p&gt;
+
let $start := 1
 +
let $end  := 10
 +
let $term  := 'welcome'
 +
for $ft in (db:open('DB')//*[text() contains text { $term }])[position() = $start to $end]
 +
return element hit {
 +
  ft:mark($ft[text() contains text { $term }])
 +
}
 +
</syntaxhighlight>
 +
'''Example 3''': The following expression returns <code>&lt;xml>hello &lt;b&gt;word&lt;/b&gt;&lt;/xml&gt;</code>:
 +
<syntaxhighlight lang="xquery">
 +
copy $p := <xml>hello world</xml>
 
modify ()
 
modify ()
return ft:mark($p[text() contains text 'word'], 'b')</pre>
+
return ft:mark($p[text() contains text 'word'], 'b')
 +
</syntaxhighlight>
 
|}
 
|}
  
 
==ft:extract==
 
==ft:extract==
{|
+
 
 +
{| width='100%'
 
|-
 
|-
| width='90' | '''Signatures'''
+
| width='120' | '''Signatures'''
|{{Func|ft:extract|$nodes as node()*|node()*}}<br />{{Func|ft:extract|$nodes as node()*, $tag as xs:string|node()*}}<br />{{Func|ft:extract|$nodes as node()*, $tag as xs:string, $length as xs:integer|node()*}}
+
|{{Func|ft:extract|$nodes as node()*|node()*}}<br />{{Func|ft:extract|$nodes as node()*, $name as xs:string|node()*}}<br />{{Func|ft:extract|$nodes as node()*, $name as xs:string, $length as xs:integer|node()*}}
 
|-
 
|-
 
| '''Summary'''
 
| '''Summary'''
|Extracts and returns relevant parts of full-text results. It puts a marker element around the resulting {{Code|$nodes}} of a full-text index request and chops irrelevant sections of the result.<br />The default tag name of the marker element is {{Code|mark}}. An alternative tag name can be chosen via the optional {{Code|$tag}} argument.<br />The default length of the returned text is {{Code|150}} characters. An alternative length can be specified via the optional {{Code|$length}} argument. Note that the effective text length may differ from the specified text due to formatting and readibility issues.
+
|Extracts and returns relevant parts of full-text results. It puts a marker element around the resulting {{Code|$nodes}} of a full-text index request and chops irrelevant sections of the result.<br />The default element name of the marker element is {{Code|mark}}. An alternative element name can be chosen via the optional {{Code|$name}} argument.<br />The default length of the returned text is {{Code|150}} characters. An alternative length can be specified via the optional {{Code|$length}} argument. Note that the effective text length may differ from the specified text due to formatting and readibility issues.<br />For more details on this function, please have a look at [[#ft:mark|ft:mark]].
 
|-
 
|-
 
| '''Examples'''
 
| '''Examples'''
 
|
 
|
 
* The following query may return {{Code|&lt;XML&gt;...&lt;b&gt;hello&lt;/b&gt;...&lt;XML&gt;}} if a text node of the database {{Code|DB}} contains the string "hello world":
 
* The following query may return {{Code|&lt;XML&gt;...&lt;b&gt;hello&lt;/b&gt;...&lt;XML&gt;}} if a text node of the database {{Code|DB}} contains the string "hello world":
<pre class="brush:xquery">
+
<syntaxhighlight lang="xquery">
 
ft:extract(db:open('DB')//*[text() contains text 'hello'], 'b', 1)
 
ft:extract(db:open('DB')//*[text() contains text 'hello'], 'b', 1)
</pre>
+
</syntaxhighlight>
 
|}
 
|}
  
 
==ft:count==
 
==ft:count==
{|
+
{| width='100%'
 
|-
 
|-
| width='90' | '''Signatures'''
+
| width='120' | '''Signatures'''
 
|{{Func|ft:count|$nodes as node()*|xs:integer}}
 
|{{Func|ft:count|$nodes as node()*|xs:integer}}
 
|-
 
|-
Line 108: Line 157:
  
 
==ft:score==
 
==ft:score==
{|
+
 
 +
{| width='100%'
 
|-
 
|-
| width='90' | '''Signatures'''
+
| width='120' | '''Signatures'''
 
|{{Func|ft:score|$item as item()*|xs:double*}}
 
|{{Func|ft:score|$item as item()*|xs:double*}}
 
|-
 
|-
Line 122: Line 172:
  
 
==ft:tokens==
 
==ft:tokens==
{|
+
{| width='100%'
 
|-
 
|-
| width='90' | '''Signatures'''
+
| width='120' | '''Signatures'''
|{{Func|ft:tokens|$db as item()|element(value)*}}<br/>{{Func|ft:tokens|$db as item(), $prefix as xs:string|element(value)*}}
+
|{{Func|ft:tokens|$db as xs:string|element(value)*}}<br/>{{Func|ft:tokens|$db as xs:string, $prefix as xs:string|element(value)*}}
 
|-
 
|-
 
| '''Summary'''
 
| '''Summary'''
|Returns all full-text tokens stored in the index of the [[Database Module#Database Nodes|database node]] {{Code|$db}}, along with their numbers of occurrences.<br/>If {{Code|$prefix}} is specified, the returned nodes will be refined to the strings starting with that prefix. The prefix will be tokenized according to the full-text used for creating the index.
+
|Returns all full-text tokens stored in the index of the database {{Code|$db}}, along with their numbers of occurrences.<br/>If {{Code|$prefix}} is specified, the returned nodes will be refined to the strings starting with that prefix. The prefix will be tokenized according to the full-text used for creating the index.
 
|-
 
|-
 
| '''Errors'''
 
| '''Errors'''
|{{Error|BXDB0004|Database Module#Errors}} the full-text index is not available.
+
|{{Error|db:open|Database Module#Errors}} The addressed database does not exist or could not be opened.<br/>{{Error|db:no-index|Database Module#Errors}} the full-text index is not available.
 +
|-
 +
| '''Examples'''
 +
|Returns the number of occurrences for a single, specific index entry:
 +
<syntaxhighlight lang="xquery">
 +
let $term := ft:tokenize($term)
 +
return number(ft:tokens('db', $term)[. = $term]/@count)
 +
</syntaxhighlight>
 
|}
 
|}
  
 
==ft:tokenize==
 
==ft:tokenize==
{|
+
 
 +
{| width='100%'
 +
|-
 +
| width='120' | '''Signatures'''
 +
|{{Func|ft:tokenize|$string as xs:string?|xs:string*}}<br/>{{Func|ft:tokenize|$string as xs:string?, $options as map(*)?|xs:string*}}
 +
|-
 +
| '''Summary'''
 +
|Tokenizes the given {{Code|$string}}, using the current default full-text options or the {{Code|$options}} specified as second argument, and returns a sequence with the tokenized string. The following options are available:
 +
* {{Code|case}}: determines how character case is processed. Allowed values are {{Code|insensitive}}, {{Code|sensitive}}, {{Code|upper}} and {{Code|lower}}. By default, search is case insensitive.
 +
* {{Code|diacritics}}: determines how diacritical characters are processed. Allowed values are {{Code|insensitive}} and {{Code|sensitive}}. By default, search is diacritical insensitive.
 +
* {{Code|stemming}}: determines is tokens are stemmed. Allowed values are {{Code|true}} and {{Code|false}}. By default, stemming is turned off.
 +
* {{Code|language}}: determines the language. This option is relevant for stemming tokens. All language codes are supported. The default language is {{Code|en}}.
 +
The {{Code|$options}} argument can be used to control full-text processing.
 +
|-
 +
| '''Examples'''
 +
|
 +
* <code>ft:tokenize("No Doubt")</code> returns the two strings {{Code|no}} and {{Code|doubt}}.
 +
* <code>ft:tokenize("École", map { 'diacritics': 'sensitive' })</code> returns the string {{Code|école}}.
 +
* <code>declare ft-option using stemming; ft:tokenize("GIFTS")</code> returns a single string {{Code|gift}}.
 +
|}
 +
 
 +
==ft:normalize==
 +
 
 +
{| width='100%'
 
|-
 
|-
| width='90' | '''Signatures'''
+
| width='120' | '''Signatures'''
|{{Func|ft:tokenize|$input as xs:string|xs:string*}}
+
|{{Func|ft:normalize|$string as xs:string?|xs:string}}<br/>{{Func|ft:normalize|$string as xs:string?, $options as map(*)?|xs:string}}
 
|-
 
|-
 
| '''Summary'''
 
| '''Summary'''
|Tokenizes the given {{Code|$input}} string, using the current default full-text options.
+
|Normalizes the given {{Code|$string}}, using the current default full-text options or the {{Code|$options}} specified as second argument. The function expects the same arguments as [[#ft:tokenize|ft:tokenize]].
 
|-
 
|-
 
| '''Examples'''
 
| '''Examples'''
 
|
 
|
* {{Code|ft:tokenize("No Doubt")}} returns the two strings {{Code|no}} and {{Code|doubt}}.
+
* <code>ft:tokenize("Häuser am Meer", map { 'case': 'sensitive' })</code> returns the string {{Code|Hauser am Meer}}.
* {{Code|declare ft-option using stemming; ft:tokenize("GIFTS")}} returns a single string {{Code|gift}}.
 
 
|}
 
|}
  
Line 152: Line 231:
  
 
{| class="wikitable" width="100%"
 
{| class="wikitable" width="100%"
! width="5%"|Code
+
! width="110"|Code
! width="95%"|Description
+
|Description
 
|-
 
|-
|{{Code|BXFT0001}}
+
|{{Code|options}}
 
|Both wildcards and fuzzy search have been specified as search options.
 
|Both wildcards and fuzzy search have been specified as search options.
 
|}
 
|}
  
 
=Changelog=
 
=Changelog=
 +
 +
; Version 9.1
 +
* Updated: [[#ft:tokenize|ft:tokenize]] and [[#ft:normalize|ft:normalize]] can be called with empty sequence.
 +
 +
;Version 9.0
 +
 +
* Updated: error codes updated; errors now use the module namespace
 +
 +
;Version 8.0
 +
 +
* Added: [[#ft:contains|ft:contains]], [[#ft:normalize|ft:normalize]]
 +
* Updated: Options added to [[#ft:tokenize|ft:tokenize]]
 +
 +
;Version 7.8
 +
 +
* Added: [[#ft:contains|ft:contains]]
 +
* Updated: Options added to [[#ft:search|ft:search]]
 +
 +
;Version 7.7
 +
 +
* Updated: the functions no longer accept [[Database Module#Database Nodes|Database Nodes]] as reference. Instead, the name of a database must now be specified.
  
 
;Version 7.2
 
;Version 7.2
Line 165: Line 265:
 
* Updated: [[#ft:search|ft:search]] (second argument generalized, third parameter added)
 
* Updated: [[#ft:search|ft:search]] (second argument generalized, third parameter added)
  
===Version 7.1===
+
;Version 7.1
  
 
* Added: [[#ft:tokens|ft:tokens]], [[#ft:tokenize|ft:tokenize]]
 
* Added: [[#ft:tokens|ft:tokens]], [[#ft:tokenize|ft:tokenize]]
 
[[Category:XQuery]]
 

Revision as of 11:33, 2 July 2020

This XQuery Module extends the W3C Full Text Recommendation with some useful functions: The index can be directly accessed, fulltext results can be marked with additional elements, or the relevant parts can be extracted. Moreover, the score value, which is generated by the contains text expression, can be explicitly requested from items.

Conventions

All functions and errors in this module are assigned to the http://basex.org/modules/ft namespace, which is statically bound to the ft prefix.

Functions

ft:search

Signatures ft:search($db as xs:string, $terms as item()*) as text()*
ft:search($db as xs:string, $terms as item()*, $options as map(*)?) as text()*
Summary Returns all text nodes from the full-text index of the database $db that contain the specified $terms.
The options used for tokenizing the input and building the full-text will also be applied to the search terms. As an example, if the index terms have been stemmed, the search string will be stemmed as well.

The $options argument can be used to control full-text processing. The following options are supported (the introduction on Full-Text processing gives you equivalent expressions in the XQuery Full-Text notation):

  • mode: determines the mode how tokens are searched. Allowed values are any, any word, all, all words, and phrase. any is the default search mode.
  • fuzzy: turns fuzzy querying on or off. Allowed values are true and false. By default, fuzzy querying is turned off.
  • wildcards: turns wildcard querying on or off. Allowed values are true and false. By default, wildcard querying is turned off.
  • ordered: requires that all tokens occur in the order in which they are specified. Allowed values are true and false. The default is false.
  • content: specifies that the matched tokens need to occur at the beginning or end of a searched string, or need to cover the entire string. Allowed values are start, end, and entire. By default, the option is turned off.
  • scope: defines the scope in which tokens must be located. The option has following sub options:
    • same: can be set to true or false. It specifies if tokens need to occur in the same or different units.
    • unit: can be sentence or paragraph. It specifies the unit for finding tokens.
  • window: sets up a window in which all tokens must be located. By default, the option is turned off. It has following sub options:
    • size: specifies the size of the window in terms of units.
    • unit: can be sentences, sentences or paragraphs. The default is words.
  • distance: specifies the distance in which tokens must occur. By default, the option is turned off. It has following sub options:
    • min: specifies the minimum distance in terms of units. The default is 0.
    • max: specifies the maximum distance in terms of units. The default is .
    • unit: can be words, sentences or paragraphs. The default is words.
Errors db:open: The addressed database does not exist or could not be opened.
db:no-index: the index is not available.
options: the fuzzy and wildcard option cannot be both specified.
Examples
  • ft:search("DB", "QUERY"): Return all text nodes of the database DB that contain the term QUERY.
  • Return all text nodes of the database DB that contain the numbers 2010 and 2020:
    ft:search("DB", ("2010", "2020"), map { 'mode': 'all' })
  • Return text nodes that contain the terms A and B in a distance of at most 5 words:

<syntaxhighlight lang="xquery"> ft:search("db", ("A", "B"), map {

 "mode": "all words",
 "distance": map {
   "max": "5",
   "unit": "words"
 }

}) </syntaxhighlight>

  • Iterate over three databases and return all elements containing terms similar to Hello World in the text nodes:

<syntaxhighlight lang="xquery"> let $terms := "Hello Worlds" let $fuzzy := true() for $db in 1 to 3 let $dbname := 'DB' || $db return ft:search($dbname, $terms, map { 'fuzzy': $fuzzy })/.. </syntaxhighlight>

ft:contains

Signatures ft:contains($input as item()*, $terms as item()*) as xs:boolean
ft:contains($input as item()*, $terms as item()*, $options as map(*)?) as xs:boolean
Summary Checks if the specified $input items contain the specified $terms.
The function does the same as the Full-Text expression contains text, but options can be specified more dynamically. The $options are the same as for ft:search, and the following ones in addition:
  • case: determines how character case is processed. Allowed values are insensitive, sensitive, upper and lower. By default, search is case insensitive.
  • diacritics: determines how diacritical characters are processed. Allowed values are insensitive and sensitive. By default, search is diacritical insensitive.
  • stemming: determines is tokens are stemmed. Allowed values are true and false. By default, stemming is turned off.
  • language: determines the language. This option is relevant for stemming tokens. All language codes are supported. The default language is en.
Errors options: specified options are conflicting.
Examples
  • Checks if jack or john occurs in the input string John Doe:

<syntaxhighlight lang="xquery"> ft:contains("John Doe", ("jack", "john"), map { "mode": "any" }) </syntaxhighlight>

  • Calls the function with stemming turned on and off:

<syntaxhighlight lang="xquery"> (true(), false()) ! ft:contains("Häuser", "Haus", map { 'stemming': ., 'language':'de' }) </syntaxhighlight>

ft:mark

Signatures ft:mark($nodes as node()*) as node()*
ft:mark($nodes as node()*, $name as xs:string) as node()*
Summary Puts a marker element around the resulting $nodes of a full-text request.
The default name of the marker element is mark. An alternative name can be chosen via the optional $name argument.
Please note that:
  • The full-text expression that computes the token positions must be specified as argument of the ft:mark() function, as all position information is lost in subsequent processing steps. You may need to specify more than one full-text expression if you want to use the function in a FLWOR expression, as shown in Example 2.
  • The supplied node must be a Database Node. As shown in Example 3, update or transform can be utilized to convert a fragment to the required internal representation.
Examples Example 1: The following query returns <XML><mark>hello</mark> world</XML>, if one text node of the database DB has the value "hello world":

<syntaxhighlight lang="xquery"> ft:mark(db:open('DB')//*[text() contains text 'hello']) </syntaxhighlight> Example 2: The following expression loops through the first ten full-text results and marks the results in a second expression: <syntaxhighlight lang="xquery"> let $start := 1 let $end := 10 let $term := 'welcome' for $ft in (db:open('DB')//*[text() contains text { $term }])[position() = $start to $end] return element hit {

 ft:mark($ft[text() contains text { $term }])

} </syntaxhighlight> Example 3: The following expression returns <xml>hello <b>word</b></xml>: <syntaxhighlight lang="xquery"> copy $p := <xml>hello world</xml> modify () return ft:mark($p[text() contains text 'word'], 'b') </syntaxhighlight>

ft:extract

Signatures ft:extract($nodes as node()*) as node()*
ft:extract($nodes as node()*, $name as xs:string) as node()*
ft:extract($nodes as node()*, $name as xs:string, $length as xs:integer) as node()*
Summary Extracts and returns relevant parts of full-text results. It puts a marker element around the resulting $nodes of a full-text index request and chops irrelevant sections of the result.
The default element name of the marker element is mark. An alternative element name can be chosen via the optional $name argument.
The default length of the returned text is 150 characters. An alternative length can be specified via the optional $length argument. Note that the effective text length may differ from the specified text due to formatting and readibility issues.
For more details on this function, please have a look at ft:mark.
Examples
  • The following query may return <XML>...<b>hello</b>...<XML> if a text node of the database DB contains the string "hello world":

<syntaxhighlight lang="xquery"> ft:extract(db:open('DB')//*[text() contains text 'hello'], 'b', 1) </syntaxhighlight>

ft:count

Signatures ft:count($nodes as node()*) as xs:integer
Summary Returns the number of occurrences of the search terms specified in a full-text expression.
Examples
  • ft:count(//*[text() contains text 'QUERY']) returns the xs:integer value 2 if a document contains two occurrences of the string "QUERY".

ft:score

Signatures ft:score($item as item()*) as xs:double*
Summary Returns the score values (0.0 - 1.0) that have been attached to the specified items. 0 is returned a value if no score was attached.
Examples
  • ft:score('a' contains text 'a') returns the xs:double value 1.

ft:tokens

Signatures ft:tokens($db as xs:string) as element(value)*
ft:tokens($db as xs:string, $prefix as xs:string) as element(value)*
Summary Returns all full-text tokens stored in the index of the database $db, along with their numbers of occurrences.
If $prefix is specified, the returned nodes will be refined to the strings starting with that prefix. The prefix will be tokenized according to the full-text used for creating the index.
Errors db:open: The addressed database does not exist or could not be opened.
db:no-index: the full-text index is not available.
Examples Returns the number of occurrences for a single, specific index entry:

<syntaxhighlight lang="xquery"> let $term := ft:tokenize($term) return number(ft:tokens('db', $term)[. = $term]/@count) </syntaxhighlight>

ft:tokenize

Signatures ft:tokenize($string as xs:string?) as xs:string*
ft:tokenize($string as xs:string?, $options as map(*)?) as xs:string*
Summary Tokenizes the given $string, using the current default full-text options or the $options specified as second argument, and returns a sequence with the tokenized string. The following options are available:
  • case: determines how character case is processed. Allowed values are insensitive, sensitive, upper and lower. By default, search is case insensitive.
  • diacritics: determines how diacritical characters are processed. Allowed values are insensitive and sensitive. By default, search is diacritical insensitive.
  • stemming: determines is tokens are stemmed. Allowed values are true and false. By default, stemming is turned off.
  • language: determines the language. This option is relevant for stemming tokens. All language codes are supported. The default language is en.

The $options argument can be used to control full-text processing.

Examples
  • ft:tokenize("No Doubt") returns the two strings no and doubt.
  • ft:tokenize("École", map { 'diacritics': 'sensitive' }) returns the string école.
  • declare ft-option using stemming; ft:tokenize("GIFTS") returns a single string gift.

ft:normalize

Signatures ft:normalize($string as xs:string?) as xs:string
ft:normalize($string as xs:string?, $options as map(*)?) as xs:string
Summary Normalizes the given $string, using the current default full-text options or the $options specified as second argument. The function expects the same arguments as ft:tokenize.
Examples
  • ft:tokenize("Häuser am Meer", map { 'case': 'sensitive' }) returns the string Hauser am Meer.

Errors

Code Description
options Both wildcards and fuzzy search have been specified as search options.

Changelog

Version 9.1
Version 9.0
  • Updated: error codes updated; errors now use the module namespace
Version 8.0
Version 7.8
Version 7.7
  • Updated: the functions no longer accept Database Nodes as reference. Instead, the name of a database must now be specified.
Version 7.2
  • Updated: ft:search (second argument generalized, third parameter added)
Version 7.1