[SOLR-2085] SolrJ fails with a NullPointerException when the order of result components changes

• Type: Bug
• Status: Closed
• Priority: Critical
• Resolution: Fixed
• Affects Version/s: 1.4
• Fix Version/s: 3.1, 4.0-ALPHA
• Component/s: clients - java
• Assignee: Chris M. Hostetter
• Reporter: Tomas Salfischberger
• Created: 24/Aug/10 12:46
• Updated: 30/Mar/11 15:45
• Resolved: 28/Jan/11 00:46

Description

When using a custom search component in Solr I noticed that the order of the "params", "response" and "facet_counts" fields in the response changed. Normally the "response" field is included before the "facet_counts" field, but in my result it first returned "facet_counts" and then "response". This is of course a valid and semantically identical result object, but it causes SolrJ to fail with a NullPointerException.

The reason for this NPE is that SolrJ in org.apache.solr.client.solrj.response.QueryResponse.setResponse(NamedList<Object> res) uses a loop through the response components and right after encountering "facet_counts" calls extractFacetInfo( _facetInfo ). That method uses _results which is null if the "response" component has not been encountered yet. (It is handled and set a few lines above the call to extractFacetInfo).

The solution is to move the call to extractFacetInfo() on line 99 out of the for-loop. Please see the attached simple patch for the solution.

I have also checked the three other initialization calls that are made directly after encountering a result (extractDebugInfo, extractHighlightingInfo and extractSpellCheckInfo), the problem does not apply to those because the methods don't access global fields that need to be initialized.

Note: It would be great if this could be applied to a maintenance release as it saves people from running a custom build to be able to use complex search components with SolrJ.