Now, what if you would like to extract metadata from an XML file, how would you go about that? This can be achieved with the XmlMetadataExtracter, which in-turn uses the XPathMetadataExtracter to navigate the XML and extract metadata. These extractors are still in the repository, see Metadata Extractors Moved to T-Engines.
Let’s say we had XML files looking like this:
<?xml version="1.0" encoding="UTF-8"?>
<doc id="doc001">
<project>
<number>PX001</number>
</project>
<securityClassification>Company Confidential</securityClassification>
<text>
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quis. Etiam maximus arcu ut metus sollicitudin laoreet. Pellentesque ac purus nec massa euismod iaculis a sed
sapien. Integer id nisi eu tellus commodo congue. In bibendum dapibus porttitor. Aenean lobortis sodales risus
....
</text>
</doc>
And whenever we upload one we want to have the /doc/@id attribute set as acme:documentId, /doc/project/number set as acme:projectNumber, and /doc/securityClassification set as acme:securityClassification. This will require configuration like this, note these are new bean definitions, no overrides:
<beanid="org.alfresco.tutorial.metadataextracter.xml.AcmeDocXPathMetadataExtracter"class="org.alfresco.repo.content.metadata.xml.XPathMetadataExtracter"parent="baseMetadataExtracter"init-method="init">
<property name="mappingProperties">
<bean class="org.springframework.beans.factory.config.PropertiesFactoryBean">
<property name="location">
<value>
classpath:alfresco/module/${project.artifactId}/metadataextraction/acme-content-model-mappings.properties
</value>
</property>
</bean>
</property>
<property name="xpathMappingProperties">
<bean class="org.springframework.beans.factory.config.PropertiesFactoryBean">
<property name="location">
<value>
classpath:alfresco/module/${project.artifactId}/metadataextraction/acme-xml-doc-xpath-mappings.properties
</value>
</property>
</bean>
</property>
</bean>
<bean id="org.alfresco.tutorial.metadataextracter.xml.selector.AcmeDocXPathSelector"
class="org.alfresco.repo.content.selector.XPathContentWorkerSelector"
init-method="init">
<property name="workers">
<map>
<entry key="/*">
<ref bean="org.alfresco.tutorial.metadataextracter.xml.AcmeDocXPathMetadataExtracter"/>
</entry>
</map>
</property>
</bean>
<bean id="org.alfresco.tutorial.metadataextracter.xml.AcmeDocXMLMetadataExtracter"
class="org.alfresco.repo.content.metadata.xml.XmlMetadataExtracter"
parent="baseMetadataExtracter">
<property name="overwritePolicy">
<value>EAGER</value> <!-- Put the extracted metadata into the content model property as long as it is not null -->
</property>
<property name="selectors">
<list>
<ref bean="org.alfresco.tutorial.metadataextracter.xml.selector.AcmeDocXPathSelector"/>
</list>
</property>
</bean>
The acme-content-model-mappings.properties file contains mappings from the extracted XML doc properties to the content model properties:
# Namespaces namespace.prefix.acme=http://www.acme.org/model/content/1.0 # Mappings - metadata property -> content model property documentId=acme:documentId securityClassification=acme:securityClassification projectNumber=acme:projectNumber
The property mapping can always be done in .properties files if we like, and we could have used a .properties file for the PDFBoxMetadataExtracter too. The other properties file called acme-xml-doc-xpath-mappings.properties contains the XPath expression configuration for where to find the metadata in the XML file:
# XPath Mappings - metadata property -> XML Document XPATH documentId=/doc/@id securityClassification=/doc/securityClassification projectNumber=/doc/project/number