Properly handle null values inside queries using LIKE or CONTAINS.

Null values are wrapped with a special handler when interacting with Hibernate. However, this becomes an issue for queries when LIKE or CONTAINS are applied. In this situation, the null needs to be condensed into an empty string and any wildcards can then be applied with expected results.

Closes #2548, #2570.
Supercedes: #2585.
Related: #2461, #2544#

Author: gregturn

src/main/java/org/springframework/data/jpa/provider/PersistenceProvider.java

@@ -40,6 +40,7 @@
 import org.springframework.lang.Nullable;
 import org.springframework.transaction.support.TransactionSynchronizationManager;
 import org.springframework.util.Assert;
+import org.springframework.util.ClassUtils;
 import org.springframework.util.ConcurrentReferenceHashMap;
 
 /**
@@ -329,6 +330,35 @@ public boolean canExtractQuery() {
 		}
 	}
 
+	/**
+	 * Because Hibernate's {@literal TypedParameterValue} is only used to wrap a {@literal null}, swap it out with an
+	 * empty string for query creation.
+	 *
+	 * @param value
+	 * @return the original value or an empty string.
+	 * @since 3.0
+	 */
+	public static Object condense(Object value) {
+
+		ClassLoader classLoader = PersistenceProvider.class.getClassLoader();
+
+		if (ClassUtils.isPresent("org.hibernate.jpa.TypedParameterValue", classLoader)) {
+
+			try {
+
+				Class<?> typeParameterValue = ClassUtils.forName("org.hibernate.jpa.TypedParameterValue", classLoader);
+
+				if (typeParameterValue.isInstance(value)) {
+					return "";
+				}
+			} catch (ClassNotFoundException | LinkageError o_O) {
+				return value;
+			}
+		}
+
+		return value;
+	}
+
 	/**
 	 * Holds the PersistenceProvider specific interface names.
 	 *

src/main/java/org/springframework/data/jpa/repository/query/ParameterMetadataProvider.java

@@ -15,12 +15,7 @@
  */
 package org.springframework.data.jpa.repository.query;
 
-import java.util.ArrayList;
-import java.util.Arrays;
-import java.util.Collection;
-import java.util.Collections;
-import java.util.Iterator;
-import java.util.List;
+import java.util.*;
 import java.util.function.Supplier;
 import java.util.stream.Collectors;
 
@@ -241,14 +236,14 @@ public Object prepare(Object value) {
 
 				switch (type) {
 					case STARTING_WITH:
-						return String.format("%s%%", escape.escape(value.toString()));
+						return String.format("%s%%", escape.escape(PersistenceProvider.condense(value).toString()));
 					case ENDING_WITH:
-						return String.format("%%%s", escape.escape(value.toString()));
+						return String.format("%%%s", escape.escape(PersistenceProvider.condense(value).toString()));
 					case CONTAINING:
 					case NOT_CONTAINING:
-						return String.format("%%%s%%", escape.escape(value.toString()));
+						return String.format("%%%s%%", escape.escape(PersistenceProvider.condense(value).toString()));
 					default:
-						return value;
+						return PersistenceProvider.condense(value);
 				}
 			}
 

src/main/java/org/springframework/data/jpa/repository/query/StringQuery.java

@@ -27,6 +27,7 @@
 import java.util.regex.Matcher;
 import java.util.regex.Pattern;
 
+import org.springframework.data.jpa.provider.PersistenceProvider;
 import org.springframework.data.repository.query.SpelQueryContext;
 import org.springframework.data.repository.query.SpelQueryContext.SpelExtractor;
 import org.springframework.data.repository.query.parser.Part.Type;
@@ -689,7 +690,7 @@ static class LikeParameterBinding extends ParameterBinding {
 
 		/**
 		 * Creates a new {@link LikeParameterBinding} for the parameter with the given name and {@link Type}.
-		 *
+		 * 
 		 * @param name must not be {@literal null} or empty.
 		 * @param type must not be {@literal null}.
 		 */
@@ -700,7 +701,7 @@ static class LikeParameterBinding extends ParameterBinding {
 		/**
 		 * Creates a new {@link LikeParameterBinding} for the parameter with the given name and {@link Type} and parameter
 		 * binding input.
-		 *
+		 * 
 		 * @param name must not be {@literal null} or empty.
 		 * @param type must not be {@literal null}.
 		 * @param expression may be {@literal null}.
@@ -770,14 +771,14 @@ public Object prepare(@Nullable Object value) {
 
 			switch (type) {
 				case STARTING_WITH:
-					return String.format("%s%%", value);
+					return String.format("%s%%", PersistenceProvider.condense(value));
 				case ENDING_WITH:
-					return String.format("%%%s", value);
+					return String.format("%%%s", PersistenceProvider.condense(value));
 				case CONTAINING:
-					return String.format("%%%s%%", value);
+					return String.format("%%%s%%", PersistenceProvider.condense(value));
 				case LIKE:
 				default:
-					return value;
+					return PersistenceProvider.condense(value);
 			}
 		}
 

src/test/java/org/springframework/data/jpa/domain/sample/EmployeeWithName.java

@@ -0,0 +1,43 @@
+/*
+ * Copyright 2012-2022 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.jpa.domain.sample;
+
+import lombok.AccessLevel;
+import lombok.Data;
+import lombok.NoArgsConstructor;
+
+import javax.persistence.Entity;
+import javax.persistence.GeneratedValue;
+import javax.persistence.Id;
+
+/**
+ * @author Greg Turnquist
+ */
+@Entity
+@NoArgsConstructor(access = AccessLevel.PROTECTED)
+@Data
+public class EmployeeWithName {
+
+	@Id
+	@GeneratedValue private Integer id;
+	private String name;
+
+	public EmployeeWithName(String name) {
+
+		this();
+		this.name = name;
+	}
+}