Polishing.

Changed default behaviour to an empty name for embedded entities.
This allows to use embedded entities for column tuples without special prefix.

Original pull request #1149

Author: schauder

spring-data-jdbc/src/test/java/org/springframework/data/jdbc/core/PersistentPropertyPathExtensionUnitTests.java

@@ -127,7 +127,7 @@ void getTableAlias() {
 			softly.assertThat(extPath("secondList.third.value").getTableAlias()).isEqualTo(quoted("secondList_third"));
 			softly.assertThat(extPath("secondList").getTableAlias()).isEqualTo(quoted("secondList"));
 			softly.assertThat(extPath("second2.third").getTableAlias()).isEqualTo(quoted("secthird"));
-			softly.assertThat(extPath("second3.third").getTableAlias()).isEqualTo(quoted("second3third"));
+			softly.assertThat(extPath("second3.third").getTableAlias()).isEqualTo(quoted("third"));
 		});
 	}
 

spring-data-relational/src/main/java/org/springframework/data/relational/core/mapping/PersistentPropertyPathExtension.java

@@ -15,6 +15,8 @@
  */
 package org.springframework.data.relational.core.mapping;
 
+import java.util.Objects;
+
 import org.springframework.data.mapping.PersistentProperty;
 import org.springframework.data.mapping.PersistentPropertyPath;
 import org.springframework.data.mapping.context.MappingContext;
@@ -23,8 +25,7 @@
 import org.springframework.data.util.Lazy;
 import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
-
-import java.util.Objects;
+import org.springframework.util.StringUtils;
 
 /**
  * A wrapper around a {@link org.springframework.data.mapping.PersistentPropertyPath} for making common operations
@@ -385,28 +386,34 @@ private PersistentPropertyPathExtension getTableOwningAncestor() {
 		return isEntity() && !isEmbedded() ? this : getParentPath().getTableOwningAncestor();
 	}
 
+	@Nullable
 	private SqlIdentifier assembleTableAlias() {
 
 		Assert.state(path != null, "Path is null");
 
 		RelationalPersistentProperty leafProperty = path.getRequiredLeafProperty();
 		String prefix;
-		if (isEmbedded() && (leafProperty.getEmbeddedPrefix() == null || !leafProperty.getEmbeddedPrefix().isEmpty())) {
+		if (isEmbedded()) {
 			prefix = leafProperty.getEmbeddedPrefix();
+
 		} else {
 			prefix = leafProperty.getName();
 		}
 
 		if (path.getLength() == 1) {
 			Assert.notNull(prefix, "Prefix mus not be null.");
-			return SqlIdentifier.quoted(prefix);
+			return StringUtils.hasText(prefix) ? SqlIdentifier.quoted(prefix) : null;
 		}
 
 		PersistentPropertyPathExtension parentPath = getParentPath();
 		SqlIdentifier sqlIdentifier = parentPath.assembleTableAlias();
 
-		return parentPath.isEmbedded() ? sqlIdentifier.transform(name -> name.concat(prefix))
-				: sqlIdentifier.transform(name -> name + "_" + prefix);
+		if (sqlIdentifier != null) {
+
+			return parentPath.isEmbedded() ? sqlIdentifier.transform(name -> name.concat(prefix))
+					: sqlIdentifier.transform(name -> name + "_" + prefix);
+		}
+		return SqlIdentifier.quoted(prefix);
 
 	}
 
@@ -444,11 +451,12 @@ private SqlIdentifier prefixWithTableAlias(SqlIdentifier columnName) {
 	@Override
 	public boolean equals(Object o) {
 
-		if (this == o) return true;
-		if (o == null || getClass() != o.getClass()) return false;
+		if (this == o)
+			return true;
+		if (o == null || getClass() != o.getClass())
+			return false;
 		PersistentPropertyPathExtension that = (PersistentPropertyPathExtension) o;
-		return entity.equals(that.entity) &&
-				Objects.equals(path, that.path);
+		return entity.equals(that.entity) && Objects.equals(path, that.path);
 	}
 
 	@Override