UpdateRequestProcessor

Solr1.3

The UpdateRequestProcessor defines how an update request is processed before it is indexed by the update handler.

Configuring UpdateRequestProcessors

solrconfig.xml will load a UpdateRequestProcessorChain

 <updateRequestProcessorChain name="mychain" >
   <processor class="solr.CustomUpdateRequestProcessorFactory" >
     <lst name="name">
       <str name="n1">x1</str>
       <str name="n2">x2</str>
     </lst>
   </processor>
   <processor class="solr.RunUpdateProcessorFactory" />
   <processor class="solr.LogUpdateProcessorFactory" />
 </updateRequestProcessorChain>

Selecting the UpdateChain for your request

Once one or more update chains are defined, you may select one on the update request through the parameter update.chain ( Note that for pre-Solr3.2 you need to use update.processor instead). Example: http://localhost:8983/solr/update/xml?update.chain=mychain. You may also choose to set a default UpdateChain for a certain UpdateRequestHandler:

 <!-- referencing it in an update handler -->
 <requestHandler name="/update/processortest" class="solr.JsonUpdateRequestHandler" >
   <lst name="defaults">
     <str name="update.chain">mychain</str>
   </lst>
 </requestHandler>

Implementing a conditional copyField

Here is a quick example that adds the 'cat' 'popular' if the value of 'popularity' is > 5

package my.solr;

import java.io.IOException;

import org.apache.solr.common.SolrInputDocument;
import org.apache.solr.request.SolrQueryRequest;
import org.apache.solr.response.SolrQueryResponse;
import org.apache.solr.update.AddUpdateCommand;
import org.apache.solr.update.processor.UpdateRequestProcessor;
import org.apache.solr.update.processor.UpdateRequestProcessorFactory;

public class ConditionalCopyProcessorFactory extends UpdateRequestProcessorFactory
{
  @Override
  public UpdateRequestProcessor getInstance(SolrQueryRequest req, SolrQueryResponse rsp, UpdateRequestProcessor next)
  {
    return new ConditionalCopyProcessor(next);
  }
}

class ConditionalCopyProcessor extends UpdateRequestProcessor
{
  public ConditionalCopyProcessor( UpdateRequestProcessor next) {
    super( next );
  }

  @Override
  public void processAdd(AddUpdateCommand cmd) throws IOException {
    SolrInputDocument doc = cmd.getSolrInputDocument();

    Object v = doc.getFieldValue( "popularity" );
    if( v != null ) {
      int pop = Integer.parseInt( v.toString() );
      if( pop > 5 ) {
        doc.addField( "cat", "popular" );
      }
    }

    // pass it up the chain
    super.processAdd(cmd);
  }
}