General Actions:
Query Module
Last modified by Thomas Mortagne on 2013/05/24 10:47
 | Allows querying the XWiki Model using a variety of query languages |
| Type | JAR |
| Developed by | |
| License | GNU Lesser General Public License 2.1 |
| Bundled With | XWiki Enterprise, XWiki Enterprise Manager |
Table of contents
Description
All data making up the XWiki application can be queried using one of the supported Query languages. Right now we support 2 languages:
- XWiki Query Language (XWQL)
- Hibernate Query Language (HQL)
Historically XWiki was only supporting HQL but that lead to complex queries in some instances and thus we've introduced XWQL which is a JPQL superset and which makes it much easier to write queries for the XWiki model, as you can see in the examples below.
Query Language Examples
| Query Description | XWQL | HQL | |
|---|---|---|---|
| Query listing all documents | <empty query> | <empty query> | |
| Query listing all documents created after a given date | where doc.creationDate > '2008-01-01' | where doc.creationDate > '2008-01-01' | |
| Query listing all documents last updated by a given user | where doc.author = 'XWiki.LudovicDubost' | where doc.author = 'XWiki.LudovicDubost' | |
| Query listing all documents containing XWiki Objects (XObject) of a given XWiki Class (XClass) | from doc.object(XWiki.XWikiUsers) as user | , BaseObject as obj where doc.fullName = obj.name and obj.className = 'XWiki.XWikiUsers' | |
| Query on XObjects and filtering on XObject property value | where doc.author = 'XWiki.LudovicDubost' and doc.object(XWiki.XWikiUsers).email like '%xwiki.com' | , BaseObject as obj, StringProperty as prop where doc.fullName = obj.name and obj.className = 'XWiki.XWikiUsers' and obj.id=prop.id.id and prop.id.name='email' and prop.value like '%xwiki.com' and doc.author ='XWiki.LudovicDubost' | |
| Query on 2 XObjects | where doc.object(XWiki.XWikiUsers).email like '%xwiki.com' and doc.object(XWiki.ArticleClass).content like '%ludovic%' | , BaseObject as obj, StringProperty as prop, BaseObject as obj2, LargeStringProperty as contentprop where doc.fullName = obj.name and obj.className = 'XWiki.XWikiUsers' and obj.id=prop.id.id and prop.id.name='email' and prop.value like '%xwiki.com' and doc.fullName=obj2.name and obj2.className='XWiki.ArticleClass' and obj2.id=contentprop.id.id and contentprop.id.name='content' and contentprop.value like '%ludovic%' | |
| Search blogs per category | where doc.fullName <> 'XWiki.ArticleClassTemplate' and :category member of doc.object(XWiki.ArticleClass).category | , BaseObject as obj, DBStringListProperty as prop join prop.list list where obj.name=doc.fullName and obj.className='XWiki.ArticleClass' and obj.name<>'XWiki.ArticleClassTemplate' and obj.id=prop.id.id and prop.id.name='category' and list='${category}' order by doc.creationDate desc | |
| List all tags | select distinct obj.tags from Document doc, doc.object(XWiki.TagClass) as obj | select distinct tag from BaseObject as obj, DBStringListProperty as prop join prop.list as tag where obj.className='XWiki.TagClass' and obj.id=prop.id.id and prop.id.name='tags' | |
| List all blog posts, published and not hidden (filter by multiple properties of an object) | from doc.object(Blog.BlogPostClass) as blog where blog.published = '1' and :category member of blog.category and blog.hidden = '0' and doc.web = 'Blog' order by blog.publishDate desc | , BaseObject as obj, IntegerProperty publishedProp, IntegerProperty hiddenProp, DateProperty publishDateProp, DBStringListProperty as categoryProp join categoryProp.list list where obj.name=doc.fullName and obj.className='Blog.BlogPostClass' and doc.space = 'Blog' and obj.id=categoryProp.id.id and categoryProp.id.name='category' and list='$category' and publishedProp.id.id = obj.id and publishedProp.id.name = 'published' and publishedProp.value = '1' and hiddenProp.id.id = obj.id and hiddenProp.id.name='hidden' and hiddenProp.value = '0' and publishDateProp.id.id = obj.id and publishDateProp.id.name='publishDate' order by publishDateProp.value desc |
Performing Queries
The principle is to get a reference to the Query Manager, then call a method on it to create a Query for a given Query language. Then on the Query object you can set some behaviors (limit the number of returned result, bind variables, set the offset, set the wiki on which to execute the query) and then execute it.
From Velocity
For XWQL:
## Return all the results from the current wiki
$services.query.xwql("xwqlstatement").execute()
## Set limit to 5 returned results at most
$services.query.xwql("xwqlstatement").setLimit(5).execute()
## Set the starting offset (starts at result number 5 and beyond)
$services.query.xwql("xwqlstatement").setOffset(5).execute()
## Set the wiki on which to run the query (requires Programming Rights before 4.1)
$services.query.xwql("xwqlstatement").setWiki("mywiki").execute()
## You can add filters to apply to the query, multiple filters can be added to a query :
## The "hidden" filter will exclude documents marked as hidden from the query results, except if the user has chosen
## to see hidden documents in his profile preferences.
$services.query.xwql("xwqlstatement").addFilter("hidden").execute()
## The "unique" will make sure you don't get duplicate results with a short-form query
$services.query.xwql("xwqlstatement").addFilter("unique").execute()
## The "count" filter allows to transform a short-form query into a count of the distinct results it would return
## Unfortunately this doesn't work with XWQL on versions older than 4.4.1 due to http://jira.xwiki.org/browse/XWIKI-8719 .
$services.query.xwql("xwqlstatement").addFilter("count").execute()
## Bind value
$services.query.xwql("xwqlstatement containing :var").bindValue("var", "value").execute()
## Behaviors can be chained
$services.query.xwql("xwqlstatement").setWiki("mywiki").setOffset(2).setLimit(5).execute()
$services.query.xwql("xwqlstatement").execute()
## Set limit to 5 returned results at most
$services.query.xwql("xwqlstatement").setLimit(5).execute()
## Set the starting offset (starts at result number 5 and beyond)
$services.query.xwql("xwqlstatement").setOffset(5).execute()
## Set the wiki on which to run the query (requires Programming Rights before 4.1)
$services.query.xwql("xwqlstatement").setWiki("mywiki").execute()
## You can add filters to apply to the query, multiple filters can be added to a query :
## The "hidden" filter will exclude documents marked as hidden from the query results, except if the user has chosen
## to see hidden documents in his profile preferences.
$services.query.xwql("xwqlstatement").addFilter("hidden").execute()
## The "unique" will make sure you don't get duplicate results with a short-form query
$services.query.xwql("xwqlstatement").addFilter("unique").execute()
## The "count" filter allows to transform a short-form query into a count of the distinct results it would return
## Unfortunately this doesn't work with XWQL on versions older than 4.4.1 due to http://jira.xwiki.org/browse/XWIKI-8719 .
$services.query.xwql("xwqlstatement").addFilter("count").execute()
## Bind value
$services.query.xwql("xwqlstatement containing :var").bindValue("var", "value").execute()
## Behaviors can be chained
$services.query.xwql("xwqlstatement").setWiki("mywiki").setOffset(2).setLimit(5).execute()
For HQL:
$services.query.hql("hqlstatement").execute()
From other Scripting languages
For XWQL (example with Groovy):
services.get("query").xwql("xwqlstatement").execute()
For HQL:
services.get("query").hql("hqlstatement").execute()
From Java components
Get a QueryManager injected. For example :
@Inject
private QueryManager queryManager;
private QueryManager queryManager;
Obtain and execute a query :
this.queryManager.createQuery(statement, Query.XWQL).execute();
XWQL Implementation Details
The XWQL grammar is defined here.
Note that currently the XWQL implementation translates queries into HQL which are then executed using Hibernate against the RDBMS.
XWiki-specific extensions in XWQL over JPQL
- Short form queries:
- where <expr> means select doc.fullName where <expr>
- from <fromlist> [where <expr>] means select doc.fullName from Document as doc, <fromlist> [where <expr>]
- Special syntax for XWiki objects in from and where clauses:
- from doc.object(Class) as obj
- where doc.object(Class).prop = 'something'
Note that any JPQL query is a correct XWQL query. This also means almost any HQL query (HQL is a JPQL superset) will work with XWQL (when executed on the XWiki Hibernate store).
Noteworthy differences between XWQL and HQL
| Description | XWQL | HQL | Details |
|---|---|---|---|
| Like statement can't be transformed in XWQL | where upper(doc.name) like 'WEBHOME' | where upper(doc.name) like upper('webhome') | The string_expression must have a string value. The pattern_value is a string literal or a string-valued input parameter |
Using the XWiki object (Deprecated)
See the Velocity HQL Guide (till we incorporate it back in this guide).