Difference between revisions of "Full-Text Module"
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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, | + | 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, 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 | + | 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/> |
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=Functions= | =Functions= | ||
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|- | |- | ||
| width='120' | '''Signatures''' | | width='120' | '''Signatures''' | ||
− | |{{Func|ft:search|$db as xs:string, $terms as item()*|text()*}}<br/>{{Func|ft:search|$db as xs:string, $terms as item()*, $options as | + | |{{Func|ft:search|$db as xs:string, $terms as item()*|text()*}}<br/>{{Func|ft:search|$db as xs:string, $terms as item()*, $options as map(*)?|text()*}} |
|- | |- | ||
| '''Summary''' | | '''Summary''' | ||
|Returns all text nodes from the full-text index of the database {{Code|$db}} that contain the specified {{Code|$terms}}.<br/>The options used for tokenizing the input and building the full-text will also be applied to the search terms. As an example, if the index terms have been stemmed, the search string will be stemmed as well. | |Returns all text nodes from the full-text index of the database {{Code|$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 control full-text processing. | + | 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): |
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− | The following options are supported (the introduction on [[Full-Text]] processing gives you equivalent expressions in the XQuery Full-Text notation): | ||
* {{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. | * {{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. | ||
* {{Code|fuzzy}}: turns fuzzy querying on or off. Allowed values are {{Code|true}} and {{Code|false}}. By default, fuzzy querying is turned off. | * {{Code|fuzzy}}: turns fuzzy querying on or off. Allowed values are {{Code|true}} and {{Code|false}}. By default, fuzzy querying is turned off. | ||
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|- | |- | ||
| '''Errors''' | | '''Errors''' | ||
− | |{{Error| | + | |{{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''' | ||
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ft:search("db", ("A", "B"), map { | ft:search("db", ("A", "B"), map { | ||
"mode": "all words", | "mode": "all words", | ||
− | "distance": { | + | "distance": map { |
"max": "5", | "max": "5", | ||
"unit": "words" | "unit": "words" | ||
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let $terms := "Hello Worlds" | let $terms := "Hello Worlds" | ||
let $fuzzy := true() | let $fuzzy := true() | ||
− | |||
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, $ | + | return ft:search($dbname, $terms, map { 'fuzzy': $fuzzy })/.. |
</pre> | </pre> | ||
|} | |} | ||
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|- | |- | ||
| width='120' | '''Signatures''' | | width='120' | '''Signatures''' | ||
− | |{{Func|ft:contains|$input as item()*, $terms as item()*|xs:boolean}}<br/>{{Func|ft:contains|$input as item()*, $terms as item()*, $options as | + | |{{Func|ft:contains|$input as item()*, $terms as item()*|xs:boolean}}<br/>{{Func|ft:contains|$input as item()*, $terms as item()*, $options as map(*)?|xs:boolean}} |
|- | |- | ||
| '''Summary''' | | '''Summary''' | ||
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| '''Errors''' | | '''Errors''' | ||
− | |{{Error| | + | |{{Error|options|#Errors}} specified options are conflicting. |
|- | |- | ||
| '''Examples''' | | '''Examples''' | ||
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==ft:mark== | ==ft:mark== | ||
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{| width='100%' | {| width='100%' | ||
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==ft:extract== | ==ft:extract== | ||
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{| width='100%' | {| width='100%' | ||
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|- | |- | ||
| '''Summary''' | | '''Summary''' | ||
− | |Extracts and returns relevant parts of full-text results. It puts a marker element around the resulting {{Code|$nodes}} of a full-text index request and chops irrelevant sections of the result.<br />The default | + | |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]]. |
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| '''Examples''' | | '''Examples''' | ||
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==ft:score== | ==ft:score== | ||
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{| width='100%' | {| width='100%' | ||
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| '''Errors''' | | '''Errors''' | ||
− | |{{Error| | + | |{{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''' | | '''Examples''' | ||
− | | | + | |Returns the number of occurrences for a single, specific index entry: |
<pre class="brush:xquery"> | <pre class="brush:xquery"> | ||
let $term := ft:tokenize($term) | let $term := ft:tokenize($term) | ||
− | return | + | return number(ft:tokens('db', $term)[. = $term]/@count) |
</pre> | </pre> | ||
|} | |} | ||
==ft:tokenize== | ==ft:tokenize== | ||
+ | |||
{| width='100%' | {| width='100%' | ||
|- | |- | ||
| width='120' | '''Signatures''' | | width='120' | '''Signatures''' | ||
− | |{{Func|ft:tokenize|$ | + | |{{Func|ft:tokenize|$string as xs:string?|xs:string*}}<br/>{{Func|ft:tokenize|$string as xs:string?, $options as map(*)?|xs:string*}} |
|- | |- | ||
| '''Summary''' | | '''Summary''' | ||
− | |Tokenizes the given {{Code|$ | + | |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|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|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|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}}. | * {{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|$options}} argument can be used to control full-text processing. | + | The {{Code|$options}} argument can be used to control full-text processing. |
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| '''Examples''' | | '''Examples''' | ||
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==ft:normalize== | ==ft:normalize== | ||
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{| width='100%' | {| width='100%' | ||
|- | |- | ||
| width='120' | '''Signatures''' | | width='120' | '''Signatures''' | ||
− | |{{Func|ft:normalize|$ | + | |{{Func|ft:normalize|$string as xs:string?|xs:string}}<br/>{{Func|ft:normalize|$string as xs:string?, $options as map(*)?|xs:string}} |
|- | |- | ||
| '''Summary''' | | '''Summary''' | ||
− | |Normalizes the given {{Code|$ | + | |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]]. |
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| '''Examples''' | | '''Examples''' | ||
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|Description | |Description | ||
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− | |{{Code| | + | |{{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 | ||
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+ | * Updated: error codes updated; errors now use the module namespace | ||
;Version 8.0 | ;Version 8.0 | ||
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* Added: [[#ft:tokens|ft:tokens]], [[#ft:tokenize|ft:tokenize]] | * Added: [[#ft:tokens|ft:tokens]], [[#ft:tokenize|ft:tokenize]] | ||
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Revision as of 14:38, 16 April 2019
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.
Contents
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
|
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", ("A", "B"), map { "mode": "all words", "distance": map { "max": "5", "unit": "words" } })
let $terms := "Hello Worlds" let $fuzzy := true() for $db in 1 to 3 let $dbname := 'DB' || $db return ft:search($dbname, $terms, map { 'fuzzy': $fuzzy })/.. |
ft:contains
Signatures | ft:contains($input as item()*, $terms as item()*) as xs:boolean ft:contains($input as item()*, $terms as item()*, $options as map(*)?) as xs:boolean
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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 $options are the same as for ft:search, and the following ones in addition:
|
Errors | options : specified options are conflicting.
|
Examples |
ft:contains("John Doe", ("jack", "john"), map { "mode": "any" })
(true(), false()) ! ft:contains("Häuser", "Haus", map { 'stemming': ., 'language':'de' }) |
ft:mark
Signatures | ft:mark($nodes as node()*) as node()* ft:mark($nodes as node()*, $name as xs:string) as node()*
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Summary | Puts a marker element around the resulting $nodes of a full-text index request.The default name of the marker element is mark . An alternative name can be chosen via the optional $name argument.Please note that:
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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":
ft:mark(db:open('DB')//*[text() contains text 'hello']) Example 2: The following expression loops through the first ten full-text results and marks the results in a second expression: 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 }]) } Example 3: The following expression returns copy $p := <p>word</p> modify () return ft:mark($p[text() contains text 'word'], 'b') |
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 $length argument. Note that the effective text length may differ from the specified text due to formatting and readibility issues.For more details on this function, please have a look at ft:mark. |
Examples |
ft:extract(db:open('DB')//*[text() contains text 'hello'], 'b', 1) |
ft:count
Signatures | ft:count($nodes as node()*) as xs:integer
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Summary | Returns the number of occurrences of the search terms specified in a full-text expression. |
Examples |
|
ft:score
Signatures | ft:score($item as item()*) as xs:double*
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Summary | Returns the score values (0.0 - 1.0) that have been attached to the specified items. 0 is returned a value if no score was attached.
|
Examples |
|
ft:tokens
Signatures | ft:tokens($db as xs:string) as element(value)* ft:tokens($db as xs:string, $prefix as xs:string) as element(value)*
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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.
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Errors | db:open : The addressed database does not exist or could not be opened.db:no-index : the full-text index is not available.
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Examples | Returns the number of occurrences for a single, specific index entry:
let $term := ft:tokenize($term) return number(ft:tokens('db', $term)[. = $term]/@count) |
ft:tokenize
Signatures | ft:tokenize($string as xs:string?) as xs:string* ft:tokenize($string as xs:string?, $options as map(*)?) as xs:string*
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Summary | Tokenizes the given $string , using the current default full-text options or the $options specified as second argument, and returns a sequence with the tokenized string. The following options are available:
The |
Examples |
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ft:normalize
Signatures | ft:normalize($string as xs:string?) as xs:string ft:normalize($string as xs:string?, $options as map(*)?) as xs:string
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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.
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Examples |
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Errors
Code | Description |
---|---|
options
|
Both wildcards and fuzzy search have been specified as search options. |
Changelog
- Version 9.1
- Updated: ft:tokenize and 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:normalize
- Updated: Options added to ft:tokenize
- Version 7.8
- Added: ft:contains
- Updated: Options added to ft:search
- 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
- Added: ft:tokens, ft:tokenize