improve error message related to window size

rest-api-spec/src/yamlRestTest/resources/rest-api-spec/test/search.retrievers/30_rescorer_retriever.yml

@@ -202,7 +202,7 @@ setup:
 ---
 "Rescorer retriever and invalid window size":
   - do:
-      catch: "/\\[rescorer\\] requires \\[rank_window_size: 5\\] be greater than or equal to \\[size: 10\\]/"
+      catch: "/\\[rescorer\\] requires \\[window_size: 5\\] be greater than or equal to \\[size: 10\\]/"
       search:
         index: test
         body:

server/src/main/java/org/elasticsearch/search/rescore/RescorerBuilder.java

@@ -39,7 +39,7 @@ public abstract class RescorerBuilder<RB extends RescorerBuilder<RB>>
 
     protected Integer windowSize;
 
-    private static final ParseField WINDOW_SIZE_FIELD = new ParseField("window_size");
+    public static final ParseField WINDOW_SIZE_FIELD = new ParseField("window_size");
 
     /**
      * Construct an empty RescoreBuilder.

server/src/main/java/org/elasticsearch/search/retriever/CompoundRetrieverBuilder.java

@@ -32,6 +32,7 @@
 import org.elasticsearch.search.sort.ScoreSortBuilder;
 import org.elasticsearch.search.sort.ShardDocSortField;
 import org.elasticsearch.search.sort.SortBuilder;
+import org.elasticsearch.xcontent.ParseField;
 
 import java.io.IOException;
 import java.util.ArrayList;
@@ -50,6 +51,8 @@ public abstract class CompoundRetrieverBuilder<T extends CompoundRetrieverBuilde
 
     public static final NodeFeature INNER_RETRIEVERS_FILTER_SUPPORT = new NodeFeature("inner_retrievers_filter_support");
 
+    public static final ParseField RANK_WINDOW_SIZE_FIELD = new ParseField("rank_window_size");
+
     public record RetrieverSource(RetrieverBuilder retriever, SearchSourceBuilder source) {}
 
     protected final int rankWindowSize;
@@ -82,6 +85,14 @@ public final boolean isCompound() {
         return true;
     }
 
+    /**
+     * Retrieves the {@link ParseField} used to configure the {@link CompoundRetrieverBuilder#rankWindowSize}
+     * at the REST layer.
+     */
+    public ParseField getRankWindowSizeField() {
+        return RANK_WINDOW_SIZE_FIELD;
+    }
+
     @Override
     public final RetrieverBuilder rewrite(QueryRewriteContext ctx) throws IOException {
         if (ctx.getPointInTimeBuilder() == null) {
@@ -210,14 +221,14 @@ public ActionRequestValidationException validate(
         validationException = super.validate(source, validationException, isScroll, allowPartialSearchResults);
         if (source.size() > rankWindowSize) {
             validationException = addValidationError(
-                "["
-                    + this.getName()
-                    + "] requires [rank_window_size: "
-                    + rankWindowSize
-                    + "]"
-                    + " be greater than or equal to [size: "
-                    + source.size()
-                    + "]",
+                String.format(
+                    Locale.ROOT,
+                    "%s requires [%s: %d] to be greater than or equal to [size: %d]",
+                    getName(),
+                    getRankWindowSizeField().getPreferredName(),
+                    rankWindowSize,
+                    source.size()
+                ),
                 validationException
             );
         }
@@ -236,10 +247,12 @@ public ActionRequestValidationException validate(
                 if (rankWindowSize > compoundChild.rankWindowSize) {
                     String errorMessage = String.format(
                         Locale.ROOT,
-                        "[%s] requires [rank_window_size: %d] to be smaller than or equal to its sub retriever's %s [rank_window_size: %d]",
+                        "[%s] requires [%s: %d] to be smaller than or equal to its sub retriever's %s [%s: %d]",
                         this.getName(),
+                        getRankWindowSizeField().getPreferredName(),
                         rankWindowSize,
                         compoundChild.getName(),
+                        compoundChild.getRankWindowSizeField(),
                         compoundChild.rankWindowSize
                     );
                     validationException = addValidationError(errorMessage, validationException);

server/src/main/java/org/elasticsearch/search/retriever/RescorerRetrieverBuilder.java

@@ -107,6 +107,11 @@ public String getName() {
         return NAME;
     }
 
+    @Override
+    public ParseField getRankWindowSizeField() {
+        return RescorerBuilder.WINDOW_SIZE_FIELD;
+    }
+
     @Override
     protected SearchSourceBuilder finalizeSourceBuilder(SearchSourceBuilder source) {
         /**

x-pack/plugin/ent-search/src/main/java/org/elasticsearch/xpack/application/rules/retriever/QueryRuleRetrieverBuilder.java

@@ -50,7 +50,6 @@ public final class QueryRuleRetrieverBuilder extends CompoundRetrieverBuilder<Qu
     public static final ParseField RULESET_IDS_FIELD = new ParseField("ruleset_ids");
     public static final ParseField MATCH_CRITERIA_FIELD = new ParseField("match_criteria");
     public static final ParseField RETRIEVER_FIELD = new ParseField("retriever");
-    public static final ParseField RANK_WINDOW_SIZE_FIELD = new ParseField("rank_window_size");
 
     @SuppressWarnings("unchecked")
     public static final ConstructingObjectParser<QueryRuleRetrieverBuilder, RetrieverParserContext> PARSER = new ConstructingObjectParser<>(

x-pack/plugin/inference/src/main/java/org/elasticsearch/xpack/inference/rank/textsimilarity/TextSimilarityRankRetrieverBuilder.java

@@ -47,7 +47,6 @@ public class TextSimilarityRankRetrieverBuilder extends CompoundRetrieverBuilder
     public static final ParseField INFERENCE_ID_FIELD = new ParseField("inference_id");
     public static final ParseField INFERENCE_TEXT_FIELD = new ParseField("inference_text");
     public static final ParseField FIELD_FIELD = new ParseField("field");
-    public static final ParseField RANK_WINDOW_SIZE_FIELD = new ParseField("rank_window_size");
 
     public static final ConstructingObjectParser<TextSimilarityRankRetrieverBuilder, RetrieverParserContext> PARSER =
         new ConstructingObjectParser<>(TextSimilarityRankBuilder.NAME, args -> {

x-pack/plugin/rank-rrf/src/main/java/org/elasticsearch/xpack/rank/rrf/RRFRetrieverBuilder.java

@@ -48,7 +48,6 @@ public final class RRFRetrieverBuilder extends CompoundRetrieverBuilder<RRFRetri
     public static final NodeFeature RRF_RETRIEVER_COMPOSITION_SUPPORTED = new NodeFeature("rrf_retriever_composition_supported");
 
     public static final ParseField RETRIEVERS_FIELD = new ParseField("retrievers");
-    public static final ParseField RANK_WINDOW_SIZE_FIELD = new ParseField("rank_window_size");
     public static final ParseField RANK_CONSTANT_FIELD = new ParseField("rank_constant");
 
     public static final int DEFAULT_RANK_CONSTANT = 60;

x-pack/plugin/rank-rrf/src/yamlRestTest/resources/rest-api-spec/test/rrf/900_rrf_with_rescorer.yml

@@ -325,7 +325,7 @@ setup:
 ---
 "RRF with rescorer retriever and invalid window size":
   - do:
-      catch: "/\\[rescorer\\] requires \\[rank_window_size: 5\\] be greater than or equal to \\[size: 10\\]/"
+      catch: "/\\[rescorer\\] requires \\[window_size: 5\\] be greater than or equal to \\[size: 10\\]/"
       search:
         index: test
         body:
@@ -367,7 +367,7 @@ setup:
           size: 10
 
   - do:
-      catch: "/\\[rescorer\\] requires \\[rank_window_size: 10\\] to be smaller than or equal to its sub retriever's rrf \\[rank_window_size: 5\\]/"
+      catch: "/\\[rescorer\\] requires \\[window_size: 10\\] to be smaller than or equal to its sub retriever's rrf \\[rank_window_size: 5\\]/"
       search:
         index: test
         body: