Support has_child and has_parent queries.

Original Pull Request: #2889
Closes #1472

Author: youssef3wi

src/main/java/org/springframework/data/elasticsearch/client/elc/AbstractQueryProcessor.java

@@ -0,0 +1,71 @@
+/*
+ * Copyright 2024 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.springframework.data.elasticsearch.client.elc;
+
+import org.springframework.data.elasticsearch.core.query.CriteriaQuery;
+import org.springframework.data.elasticsearch.core.query.Query;
+import org.springframework.data.elasticsearch.core.query.StringQuery;
+import org.springframework.lang.Nullable;
+import org.springframework.util.Assert;
+
+import java.util.function.Consumer;
+
+/**
+ * An abstract class that serves as a base for query processors.
+ * It provides a common interface and basic functionality for query processing.
+ *
+ * @author Aouichaoui Youssef
+ * @since 5.3
+ */
+public abstract class AbstractQueryProcessor {
+
+    /**
+     * Convert a spring-data-elasticsearch {@literal query} to an Elasticsearch {@literal query}.
+     *
+     * @param query          spring-data-elasticsearch {@literal query}.
+     * @param queryConverter correct mapped field names and the values to the converted values.
+     * @return an Elasticsearch {@literal query}.
+     */
+    @Nullable
+    static co.elastic.clients.elasticsearch._types.query_dsl.Query getEsQuery(@Nullable Query query,
+                                                                              @Nullable Consumer<Query> queryConverter) {
+        if (query == null) {
+            return null;
+        }
+
+        if (queryConverter != null) {
+            queryConverter.accept(query);
+        }
+
+        co.elastic.clients.elasticsearch._types.query_dsl.Query esQuery = null;
+
+        if (query instanceof CriteriaQuery criteriaQuery) {
+            esQuery = CriteriaQueryProcessor.createQuery(criteriaQuery.getCriteria());
+        } else if (query instanceof StringQuery stringQuery) {
+            esQuery = Queries.wrapperQueryAsQuery(stringQuery.getSource());
+        } else if (query instanceof NativeQuery nativeQuery) {
+            if (nativeQuery.getQuery() != null) {
+                esQuery = nativeQuery.getQuery();
+            } else if (nativeQuery.getSpringDataQuery() != null) {
+                esQuery = getEsQuery(nativeQuery.getSpringDataQuery(), queryConverter);
+            }
+        } else {
+            throw new IllegalArgumentException("unhandled Query implementation " + query.getClass().getName());
+        }
+
+        return esQuery;
+    }
+}

src/main/java/org/springframework/data/elasticsearch/client/elc/CriteriaQueryProcessor.java

@@ -16,12 +16,14 @@
 package org.springframework.data.elasticsearch.client.elc;
 
 import static org.springframework.data.elasticsearch.client.elc.Queries.*;
+import static org.springframework.data.elasticsearch.client.elc.TypeUtils.scoreMode;
 import static org.springframework.util.StringUtils.*;
 
 import co.elastic.clients.elasticsearch._types.FieldValue;
 import co.elastic.clients.elasticsearch._types.query_dsl.ChildScoreMode;
 import co.elastic.clients.elasticsearch._types.query_dsl.Operator;
 import co.elastic.clients.elasticsearch._types.query_dsl.Query;
+import co.elastic.clients.elasticsearch.core.search.InnerHits;
 import co.elastic.clients.json.JsonData;
 
 import java.util.ArrayList;
@@ -30,7 +32,12 @@
 
 import org.springframework.data.elasticsearch.annotations.FieldType;
 import org.springframework.data.elasticsearch.core.query.Criteria;
+import org.springframework.data.elasticsearch.core.query.CriteriaQuery;
 import org.springframework.data.elasticsearch.core.query.Field;
+import org.springframework.data.elasticsearch.core.query.HasChildQuery;
+import org.springframework.data.elasticsearch.core.query.HasParentQuery;
+import org.springframework.data.elasticsearch.core.query.InnerHitsQuery;
+import org.springframework.data.elasticsearch.core.query.StringQuery;
 import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 
@@ -42,7 +49,7 @@
  * @author Ezequiel Antúnez Camacho
  * @since 4.4
  */
-class CriteriaQueryProcessor {
+class CriteriaQueryProcessor extends AbstractQueryProcessor {
 
 	/**
 	 * creates a query from the criteria
@@ -343,6 +350,34 @@ private static Query.Builder queryFor(Criteria.CriteriaEntry entry, Field field,
 								.value(value.toString()) //
 								.boost(boost)); //
 				break;
+			case HAS_CHILD:
+				if (value instanceof HasChildQuery query) {
+					queryBuilder.hasChild(hcb -> hcb
+							.type(query.getType())
+							.query(getEsQuery(query.getQuery(), null))
+							.innerHits(getInnerHits(query.getInnerHitsQuery()))
+							.ignoreUnmapped(query.getIgnoreUnmapped())
+                            .minChildren(query.getMinChildren())
+                            .maxChildren(query.getMaxChildren())
+                            .scoreMode(scoreMode(query.getScoreMode()))
+					);
+				} else {
+					throw new CriteriaQueryException("value for " + fieldName + " is not a has_child query");
+				}
+                break;
+            case HAS_PARENT:
+                if (value instanceof HasParentQuery query) {
+					queryBuilder.hasParent(hpb -> hpb
+							.parentType(query.getParentType())
+							.query(getEsQuery(query.getQuery(), null))
+							.innerHits(getInnerHits(query.getInnerHitsQuery()))
+							.ignoreUnmapped(query.getIgnoreUnmapped())
+							.score(query.getScore())
+					);
+                } else {
+                    throw new CriteriaQueryException("value for " + fieldName + " is not a has_parent query");
+                }
+                break;
 			default:
 				throw new CriteriaQueryException("Could not build query for " + entry);
 		}
@@ -397,4 +432,19 @@ public static String escape(String s) {
 		return sb.toString();
 	}
 
+    /**
+     * Convert a spring-data-elasticsearch {@literal inner_hits} to an Elasticsearch {@literal inner_hits} query.
+     *
+     * @param query spring-data-elasticsearch {@literal inner_hits}.
+     * @return an Elasticsearch {@literal inner_hits} query.
+     */
+    @Nullable
+    private static InnerHits getInnerHits(@Nullable InnerHitsQuery query) {
+        if (query == null) {
+            return null;
+        }
+
+        return InnerHits.of(iqb -> iqb.from(query.getFrom()).size(query.getSize()).name(query.getName()));
+    }
+
 }

src/main/java/org/springframework/data/elasticsearch/client/elc/RequestConverter.java

@@ -112,7 +112,7 @@
  * @since 4.4
  */
 @SuppressWarnings("ClassCanBeRecord")
-class RequestConverter {
+class RequestConverter extends AbstractQueryProcessor {
 
 	private static final Log LOGGER = LogFactory.getLog(RequestConverter.class);
 
@@ -1755,31 +1755,7 @@ private void prepareNativeSearch(NativeQuery query, MultisearchBody.Builder buil
 	@Nullable
 	co.elastic.clients.elasticsearch._types.query_dsl.Query getQuery(@Nullable Query query,
 			@Nullable Class<?> clazz) {
-
-		if (query == null) {
-			return null;
-		}
-
-		elasticsearchConverter.updateQuery(query, clazz);
-
-		co.elastic.clients.elasticsearch._types.query_dsl.Query esQuery = null;
-
-		if (query instanceof CriteriaQuery) {
-			esQuery = CriteriaQueryProcessor.createQuery(((CriteriaQuery) query).getCriteria());
-		} else if (query instanceof StringQuery) {
-			esQuery = Queries.wrapperQueryAsQuery(((StringQuery) query).getSource());
-		} else if (query instanceof NativeQuery nativeQuery) {
-
-			if (nativeQuery.getQuery() != null) {
-				esQuery = nativeQuery.getQuery();
-			} else if (nativeQuery.getSpringDataQuery() != null) {
-				esQuery = getQuery(nativeQuery.getSpringDataQuery(), clazz);
-			}
-		} else {
-			throw new IllegalArgumentException("unhandled Query implementation " + query.getClass().getName());
-		}
-
-		return esQuery;
+		return getEsQuery(query, (q) -> elasticsearchConverter.updateQuery(q, clazz));
 	}
 
 	private void addFilter(Query query, SearchRequest.Builder builder) {

src/main/java/org/springframework/data/elasticsearch/client/elc/TypeUtils.java

@@ -18,6 +18,7 @@
 import co.elastic.clients.elasticsearch._types.*;
 import co.elastic.clients.elasticsearch._types.mapping.FieldType;
 import co.elastic.clients.elasticsearch._types.mapping.TypeMapping;
+import co.elastic.clients.elasticsearch._types.query_dsl.ChildScoreMode;
 import co.elastic.clients.elasticsearch._types.query_dsl.Operator;
 import co.elastic.clients.elasticsearch.core.search.BoundaryScanner;
 import co.elastic.clients.elasticsearch.core.search.HighlighterEncoder;
@@ -41,6 +42,7 @@
 import org.springframework.data.elasticsearch.core.RefreshPolicy;
 import org.springframework.data.elasticsearch.core.document.Document;
 import org.springframework.data.elasticsearch.core.query.GeoDistanceOrder;
+import org.springframework.data.elasticsearch.core.query.HasChildQuery;
 import org.springframework.data.elasticsearch.core.query.IndexQuery;
 import org.springframework.data.elasticsearch.core.query.IndicesOptions;
 import org.springframework.data.elasticsearch.core.query.Order;
@@ -527,4 +529,24 @@ static Operator operator(@Nullable OperatorType operator) {
 	static Conflicts conflicts(@Nullable ConflictsType conflicts) {
 		return conflicts != null ? Conflicts.valueOf(conflicts.name()) : null;
 	}
+
+	/**
+	 * Convert a spring-data-elasticsearch {@literal scoreMode} to an Elasticsearch {@literal scoreMode}.
+	 *
+	 * @param scoreMode spring-data-elasticsearch {@literal scoreMode}.
+	 * @return an Elasticsearch {@literal scoreMode}.
+	 */
+	static ChildScoreMode scoreMode(@Nullable HasChildQuery.ScoreMode scoreMode) {
+		if (scoreMode == null) {
+			return ChildScoreMode.None;
+		}
+
+		return switch (scoreMode) {
+			case Avg -> ChildScoreMode.Avg;
+			case Max -> ChildScoreMode.Max;
+			case Min -> ChildScoreMode.Min;
+			case Sum -> ChildScoreMode.Sum;
+			default -> ChildScoreMode.None;
+		};
+	}
 }

src/main/java/org/springframework/data/elasticsearch/core/query/Criteria.java

@@ -816,6 +816,32 @@ public Criteria contains(GeoJson<?> geoShape) {
 		filterCriteriaEntries.add(new CriteriaEntry(OperationKey.GEO_CONTAINS, geoShape));
 		return this;
 	}
+
+	/**
+	 * Adds a new filter CriteriaEntry for HAS_CHILD.
+	 *
+	 * @param query the has_child query.
+	 * @return the current Criteria.
+	 */
+	public Criteria hasChild(HasChildQuery query) {
+		Assert.notNull(query, "has_child query must not be null.");
+
+		queryCriteriaEntries.add(new CriteriaEntry(OperationKey.HAS_CHILD, query));
+		return this;
+	}
+
+	/**
+	 * Adds a new filter CriteriaEntry for HAS_PARENT.
+	 *
+	 * @param query the has_parent query.
+	 * @return the current Criteria.
+	 */
+	public Criteria hasParent(HasParentQuery query) {
+		Assert.notNull(query, "has_parent query must not be null.");
+
+		queryCriteriaEntries.add(new CriteriaEntry(OperationKey.HAS_PARENT, query));
+		return this;
+	}
 	// endregion
 
 	// region helper functions
@@ -977,7 +1003,12 @@ public enum OperationKey { //
 		/**
 		 * @since 5.1
 		 */
-		REGEXP;
+		REGEXP,
+		/**
+		 * @since 5.3
+		 */
+		HAS_CHILD,
+		HAS_PARENT;
 
 		/**
 		 * @return true if this key does not have an associated value