DigitalPebble's Blog: Using Payloads with DisMaxQParser in SOLR
and we can also define a custom Similarity to use with the payloads
I have implemented a modified version of DismaxQueryParser which rewrites the main part of the query (a.k.a userQuery in the implementation) and substitutes the TermQueries with PayloadTermQueries.
Read full article from DigitalPebble's Blog: Using Payloads with DisMaxQParser in SOLR
What I will describe here is how to use the payloads and have the functionalities of the DisMaxQParser in SOLR.
SOLR already has a field type for analysing payloads
<fieldtype name="payloads" stored="false" indexed="true" class="solr.TextField" ><analyzer><tokenizer class="solr.WhitespaceTokenizerFactory"/><!--The DelimitedPayloadTokenFilter can put payloads on tokens... for example,a token of "foo|1.4" would be indexed as "foo" with a payload of 1.4fAttributes of the DelimitedPayloadTokenFilterFactory :"delimiter" - a one character delimiter. Default is | (pipe)"encoder" - how to encode the following value into a playloadfloat -> org.apache.lucene.analysis.payloads.FloatEncoder,integer -> o.a.l.a.p.IntegerEncoderidentity -> o.a.l.a.p.IdentityEncoderFully Qualified class name implementing PayloadEncoder, Encoder must have a no arg constructor.--><filter class="solr.DelimitedPayloadTokenFilterFactory" encoder="float"/></analyzer></fieldtype>
public class PayloadSimilarity extends DefaultSimilarity{@Override public float scorePayload(int docId, String fieldName, int start, int end, byte[] payload, int offset, int length){if (length > 0) {return PayloadHelper.decodeFloat(payload, offset);}return 1.0f;}}
then specify this in the SOLR schema
<!-- schema.xml -->
<similarity class="uk.org.company.solr.PayloadSimilarity" />
<similarity class="uk.org.company.solr.PayloadSimilarity" />
We now need a QueryParser plugin in order to use the payloads in the search and as mentioned above, I want to keep the functionalities of the DisMaxQueryParser.
The problem is that we need to specify PayloadTermQuery objects instead of TermQueries which is down deep in the object hierarchies and cannot AFAIK be modified simply from DismaxQueryParser.I have implemented a modified version of DismaxQueryParser which rewrites the main part of the query (a.k.a userQuery in the implementation) and substitutes the TermQueries with PayloadTermQueries.
First we'll create a QParserPlugin
public class PLDisMaxQParser extends DisMaxQParser {public static final String PAYLOAD_FIELDS_PARAM_NAME = "plf";public PLDisMaxQParser(String qstr, SolrParams localParams,SolrParams params, SolrQueryRequest req) {super(qstr, localParams, params, req);}protected HashSet<String> payloadFields = new HashSet<String>();private static final PayloadFunction func = new MaxPayloadFunction();float tiebreaker = 0f;protected void addMainQuery(BooleanQuery query, SolrParams solrParams)throws ParseException {Map<String, Float> phraseFields = SolrPluginUtils.parseFieldBoosts(solrParams.getParams(DisMaxParams.PF));tiebreaker = solrParams.getFloat(DisMaxParams.TIE, 0.0f);// get the comma separated list of fields used for payloadString[] plfarray = solrParams.get(PAYLOAD_FIELDS_PARAM_NAME, "").split(",");for (String plf : plfarray)payloadFields.add(plf.trim());/** a parser for dealing with user input, which will convert things to* DisjunctionMaxQueries*/SolrPluginUtils.DisjunctionMaxQueryParser up = getParser(queryFields,DisMaxParams.QS, solrParams, tiebreaker);/* for parsing sloppy phrases using DisjunctionMaxQueries */SolrPluginUtils.DisjunctionMaxQueryParser pp = getParser(phraseFields,DisMaxParams.PS, solrParams, tiebreaker);/* * * Main User Query * * */parsedUserQuery = null;String userQuery = getString();altUserQuery = null;if (userQuery == null || userQuery.trim().length() < 1) {// If no query is specified, we may have an alternatealtUserQuery = getAlternateUserQuery(solrParams);query.add(altUserQuery, BooleanClause.Occur.MUST);} else {// There is a valid query stringuserQuery = SolrPluginUtils.partialEscape(SolrPluginUtils.stripUnbalancedQuotes(userQuery)).toString();userQuery = SolrPluginUtils.stripIllegalOperators(userQuery).toString();parsedUserQuery = getUserQuery(userQuery, up, solrParams);// recursively rewrite the elements of the queryQuery payloadedUserQuery = rewriteQueriesAsPLQueries(parsedUserQuery);query.add(payloadedUserQuery, BooleanClause.Occur.MUST);Query phrase = getPhraseQuery(userQuery, pp);if (null != phrase) {query.add(phrase, BooleanClause.Occur.SHOULD);}}}/** Substitutes original query objects with payload ones **/private Query rewriteQueriesAsPLQueries(Query input) {Query output = input;// rewrite TermQueriesif (input instanceof TermQuery) {Term term = ((TermQuery) input).getTerm();// check that this is done on a field that has payloadsif (payloadFields.contains(term.field()) == false)return input;output = new PayloadTermQuery(term, func);}// rewrite PhraseQuerieselse if (input instanceof PhraseQuery) {PhraseQuery pin = (PhraseQuery) input;Term[] terms = pin.getTerms();int slop = pin.getSlop();boolean inorder = false;// check that this is done on a field that has payloadsif (terms.length > 0&& payloadFields.contains(terms[0].field()) == false)return input;SpanQuery[] clauses = new SpanQuery[terms.length];// phrase queries : keep the default function i.e. averagefor (int i = 0; i < terms.length; i++)clauses[i] = new PayloadTermQuery(terms[i], func);output = new PayloadNearQuery(clauses, slop, inorder);}// recursively rewrite DJMQselse if (input instanceof DisjunctionMaxQuery) {DisjunctionMaxQuery s = ((DisjunctionMaxQuery) input);DisjunctionMaxQuery t = new DisjunctionMaxQuery(tiebreaker);Iterator<Query> disjunctsiterator = s.iterator();while (disjunctsiterator.hasNext()) {Query rewrittenQuery = rewriteQueriesAsPLQueries(disjunctsiterator.next());t.add(rewrittenQuery);}output = t;}// recursively rewrite BooleanQuerieselse if (input instanceof BooleanQuery) {for (BooleanClause clause : (List<BooleanClause>) ((BooleanQuery) input).clauses()) {Query rewrittenQuery = rewriteQueriesAsPLQueries(clause.getQuery());clause.setQuery(rewrittenQuery);}}output.setBoost(input.getBoost());return output;}public void addDebugInfo(NamedList<Object> debugInfo) {super.addDebugInfo(debugInfo);if (this.payloadFields.size() > 0) {Iterator<String> iter = this.payloadFields.iterator();while (iter.hasNext())debugInfo.add("payloadField", iter.next());}}}
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