XQuery/Using Triggers to Log Events

Motivation You want to log all changes in files of a single collection. Method We will create a trigger that logs these events. The trigger will append a string to a log file. There are six trigger event types: store: Fired when a document is created in the collection or sub-collection update: Fired when a document is updated in the collection or sub-collection remove: Fired when a document is deleted from the collection or sub-collection create: Fired when a sub-collection is created rename: Fired when a sub-collection is renamed delete: Fired when a sub-collection is deleted Sample Code NOTE: These examples do not reliably work on eXist 1.4! I have not yet tested on 2.0. In this example we will be logging all store, update and remove events from the collection /db/my-collection Here is a sample trigger configuration file. This file is placed in the /db/system/config are with the same db path added to it that you want to monitor: /db/system/config/db/my-collection Here is what the trigger file looks like: collection.xconf <collection xmlns="http://exist-db.org/collection-config/1.0"> <triggers> <trigger event="store, update, remove, create, rename, delete" class="org.exist.collections.triggers.XQueryTrigger"> <parameter name="url" value="xmldb:exist://localhost/db/triggers/log-changes.xq"/> <parameter name="test" value="test-value"/> </trigger> </triggers> </collection> Note that the three trigger operations (store, update, remove) are listed in the event attribute and separated by commas. When these operations are fired the XQuery /db/triggers/log-changes.xq gets run. You can pass parameters to this query using the parameter element. XQuery logger xquery version "1.0"; declare namespace request="http://exist-db.org/xquery/request"; declare namespace response="http://exist-db.org/xquery/response"; declare namespace session="http://exist-db.org/xquery/session"; declare namespace xdb="http://exist-db.org/xquery/xmldb"; declare namespace util="http://exist-db.org/xquery/util"; declare variable $local:triggerEvent external; declare variable $local:eventType external; declare variable $local:collectionName external; declare variable $local:documentName external; declare variable $local:document external; declare variable $local:test external; declare variable $local:triggersLogFile := "triggersLog.xml"; (: create the log file if it does not exist :) if(not(doc-available($local:triggersLogFile))) then ( xmldb:store("/db", $local:triggersLogFile, <events/>) ) else(), update insert <event ts="{ current-dateTime() }" event="{$local:triggerEvent}" eventType="{$local:eventType}" test-1="{$local:test}" collectionName="{$local:collectionName}" documentName="{$local:documentName}" > {$local:document} </event> into doc(concat("/db/", $local:triggersLogFile))/events References Guide to configuring eXist triggers