Parsing SolrJ Facet Pivot Response - solr

Question

I have a Solr Schema and I am trying to do Facet Pivoting on it by passing multiple fields in facet.pivot parameter while making a call through SolrJ. My Solr response looks something like below:
"facet_pivot": {
"boolean_value,int_value": [
{
"field": "boolean_value",
"value": false,
"count": 1,
"pivot": [
{
"field": "int_value",
"value": 364,
"count": 1
}
]
},
{
"field": "boolean_value",
"value": true,
"count": 2,
"pivot": [
{
"field": "int_value",
"value": 406,
"count": 1
},
{
"field": "int_value",
"value": 409,
"count": 1
}
]
}
]
}
How, can I parse the above response using SolrJ in form of Nested objects i.e. PivotField having relation of which int_value falls under which boolean_value.
SolrJ Version tried: 4.10.4
Update:
When you make a call through SolrJ check the SolrQuery that gets generated. In my above case the SolrQuery was:
facet.pivot=boolean_value&facet.pivot=int_value
Solr considers above pivots as two different ones and you won't get nested pivoting. For Nested Pivoting your SolrQuery should have
facet.pivot=boolean_value,int_value

Answer 1

I had the same problem and wrote a simple tester application. It queries Solr and writes the pivot values to StdOut as hierarchical Strings. If there are any suggestions to implement that more nicely, please let me know. Here's the code:
public class Tester {
public static final String HIERARCHICAL_FACET_SEPARATOR = "/";
public static void main(String[] args) throws SolrServerException, IOException {
CloudSolrClient solr = ... ;
SolrQuery query = new SolrQuery(...);
query.setFacet(true);
query.addFacetPivotField(new String[]{"field1,field2,field3"});
QueryResponse result = solr.query(query);
NamedList<List<PivotField>> facetPivot = result.getFacetPivot();
List<String> parsedPivotResult = parsePivotResult(facetPivot);
parsedPivotResult.forEach((s) -> {
System.out.println(s);
});
}
private static List<String> parsePivotResult(final NamedList<List<PivotField>> pivotEntryList) {
final Set<String> outputItems = new HashSet<>();
for (final Entry<String, List<PivotField>> pivotEntry : pivotEntryList) {
System.out.println("Key: " + pivotEntry.getKey());
pivotEntry.getValue().forEach((pivotField) -> {
renderOutput(new StringBuilder(), pivotField, outputItems);
});
}
final List<String> output = new ArrayList<>(outputItems);
Collections.sort(output);
return output;
}
private static void renderOutput(final StringBuilder sb, final PivotField field, final Set<String> outputItems) {
final String fieldValue = field.getValue() != null ? ((String) field.getValue()).trim() : null;
final StringBuilder outputBuilder = new StringBuilder(sb);
if (field.getPivot() != null) {
if (outputBuilder.length() > 0) {
outputBuilder.append(HIERARCHICAL_FACET_SEPARATOR);
}
outputBuilder.append(fieldValue);
outputItems.add(new StringBuilder(outputBuilder).append(" (").append(field.getCount()).append(")").toString());
field.getPivot().forEach((subField) -> {
renderOutput(outputBuilder, subField, outputItems);
});
} else {
if (outputBuilder.length() > 0) {
outputBuilder.append(HIERARCHICAL_FACET_SEPARATOR);
}
outputBuilder.append(fieldValue);
outputItems.add(outputBuilder.append(" (").append(field.getCount()).append(")").toString());
}
}
}