SOLR-8902: Make sure ReturnFields only returns the requested fields

solr/CHANGES.txt

@@ -55,6 +55,9 @@ Bug Fixes
 * SOLR-8857: HdfsUpdateLog does not use configured or new default number of version buckets and is
   hard coded to 256. (Mark Miller, yonik, Gregory Chanan)
 
+* SOLR-8902: Make sure ReturnFields only returns the requested fields from (fl=) evn when 
+  DocumentTransformers ask for getExtraRequestFields()  (ryan)
+
 Optimizations
 ----------------------
 * SOLR-8722: Don't force a full ZkStateReader refresh on every Overseer operation.

solr/core/src/java/org/apache/solr/response/BinaryResponseWriter.java

@@ -72,8 +72,7 @@ public class BinaryResponseWriter implements BinaryQueryResponseWriter {
   public static class Resolver implements JavaBinCodec.ObjectResolver , JavaBinCodec.WritableDocFields {
     protected final SolrQueryRequest solrQueryRequest;
     protected IndexSchema schema;
-    protected SolrIndexSearcher searcher; // TODO - this is never set?  always null?
+    protected ReturnFields returnFields;
-    protected final ReturnFields returnFields;
 
     public Resolver(SolrQueryRequest req, ReturnFields returnFields) {
       solrQueryRequest = req;
@@ -83,7 +82,13 @@ public class BinaryResponseWriter implements BinaryQueryResponseWriter {
     @Override
     public Object resolve(Object o, JavaBinCodec codec) throws IOException {
       if (o instanceof ResultContext) {
-        writeResults((ResultContext) o, codec);
+        ReturnFields orig = returnFields;
+        ResultContext res = (ResultContext)o;
+        if(res.getReturnFields()!=null) {
+          returnFields = res.getReturnFields();
+        }
+        writeResults(res, codec);
+        returnFields = orig;
         return null; // null means we completely handled it
       }
       if (o instanceof DocList) {

solr/core/src/java/org/apache/solr/search/SolrReturnFields.java

@@ -51,6 +51,7 @@ public class SolrReturnFields extends ReturnFields {
   private final List<String> globs = new ArrayList<>(1);
 
   // The lucene field names to request from the SolrIndexSearcher
+  // This *may* include fields that will not be in the final response
   private final Set<String> fields = new HashSet<>();
 
   // Field names that are OK to include in the response.
@@ -130,17 +131,6 @@ public class SolrReturnFields extends ReturnFields {
       augmenters.addTransformer( new RenameFieldTransformer( from, to, copy ) );
     }
 
-    if( !_wantsAllFields ) {
-      if( !globs.isEmpty() ) {
-        // TODO??? need to fill up the fields with matching field names in the index
-        // and add them to okFieldNames?
-        // maybe just get all fields?
-        // this would disable field selection optimization... i think thatis OK
-        fields.clear(); // this will get all fields, and use wantsField to limit
-      }
-      okFieldNames.addAll( fields );
-    }
-
     if( augmenters.size() == 1 ) {
       transformer = augmenters.getTransformer(0);
     }

solr/core/src/test/org/apache/solr/search/ReturnFieldsTest.java

@@ -264,6 +264,14 @@ public class ReturnFieldsTest extends SolrTestCaseJ4 {
     assertFalse( rf.wantsField( "id" ) );
     assertFalse(rf.wantsAllFields());
     assertNull(rf.getTransformer());
+
+    // Don't return 'store_rpt' just because it is required by the transformer
+    rf = new SolrReturnFields( req("fl", "[geo f=store_rpt]") );
+    assertFalse( rf.wantsScore() );
+    assertTrue(rf.wantsField("[geo]"));
+    assertFalse( rf.wantsField( "store_rpt" ) );
+    assertFalse(rf.wantsAllFields());
+    assertNotNull(rf.getTransformer());
   }
 
   @Test