Polishing.

Simplified the code structure.
Ensured backward compatibility by recreating some methods often immediately deprecating them.

Moved new classes to the places where they belong, so that the package ...core.sql.render depends on ...core.dialect and not the other way round.
This causes dependency cycles because dependencies in the other direction already exists.
This will be properly fixed by #1105.
For now the offending classes are ignored by the DependencyTests.

See #777
See #1105

Polishing

Author: schauder

Diff for: spring-data-jdbc/src/main/java/org/springframework/data/jdbc/core/convert/SqlGenerator.java

@@ -93,14 +93,12 @@ class SqlGenerator {
 	SqlGenerator(RelationalMappingContext mappingContext, JdbcConverter converter, RelationalPersistentEntity<?> entity,
 			Dialect dialect) {
 
-		final RenderContextFactory renderContextFactory = new RenderContextFactory(dialect);
-
 		this.mappingContext = mappingContext;
 		this.entity = entity;
 		this.sqlContext = new SqlContext(entity);
-		this.sqlRenderer = SqlRenderer.create(renderContextFactory.createRenderContext());
+		this.renderContext = new RenderContextFactory(dialect).createRenderContext();
+		this.sqlRenderer = SqlRenderer.create(renderContext);
 		this.columns = new Columns(entity, mappingContext, converter);
-		this.renderContext = renderContextFactory.createRenderContext();
 	}
 
 	/**

Diff for: spring-data-jdbc/src/test/java/org/springframework/data/jdbc/core/JdbcAggregateTemplateIntegrationTests.java

@@ -888,9 +888,11 @@ public void saveAndLoadDateTimeWithMicrosecondPrecision() {
 		assertThat(loaded.testTime).isEqualTo(entity.testTime);
 	}
 
-	@Test // DATAJDBC-557
+	@Test // GH-777
 	public void insertWithIdOnly() {
+
 		WithIdOnly entity = new WithIdOnly();
+
 		assertThat(template.save(entity).id).isNotNull();
 	}
 

Diff for: spring-data-jdbc/src/test/java/org/springframework/data/jdbc/core/convert/DefaultDataAccessStrategyUnitTests.java

@@ -219,7 +219,7 @@ public void insertWithUndefinedIdRetrievesGeneratedKeys() {
 
 		assertThat(generatedId).isEqualTo(GENERATED_ID);
 
-		verify(namedJdbcOperations).update(eq("INSERT INTO \"DUMMY_ENTITY\" VALUES ()"),
+		verify(namedJdbcOperations).update(eq("INSERT INTO \"DUMMY_ENTITY\" VALUES (DEFAULT)"),
 				paramSourceCaptor.capture(), any(KeyHolder.class));
 	}
 

Diff for: spring-data-jdbc/src/test/java/org/springframework/data/jdbc/core/convert/SqlGeneratorUnitTests.java

@@ -398,18 +398,19 @@ void getInsertForEmptyColumnListPostgres() {
 
 		SqlGenerator sqlGenerator = createSqlGenerator(IdOnlyEntity.class, PostgresDialect.INSTANCE);
 
-		String insertSqlStatement = sqlGenerator.getInsert(emptySet());
+		String insert = sqlGenerator.getInsert(emptySet());
 
-		assertThat(insertSqlStatement).endsWith(" VALUES (DEFAULT) ");
+		assertThat(insert).endsWith(" VALUES (DEFAULT)");
 	}
 
-	@Test //DATAJDBC-557
+	@Test // GH-777
 	void gerInsertForEmptyColumnListMsSqlServer() {
+
 		SqlGenerator sqlGenerator = createSqlGenerator(IdOnlyEntity.class, SqlServerDialect.INSTANCE);
 
-		String insertSqlStatement = sqlGenerator.getInsert(emptySet());
+		String insert = sqlGenerator.getInsert(emptySet());
 
-		assertThat(insertSqlStatement).endsWith(" DEFAULT VALUES ");
+		assertThat(insert).endsWith(" DEFAULT VALUES");
 	}
 
 	@Test // DATAJDBC-334

Diff for: spring-data-relational/src/main/java/org/springframework/data/relational/core/dialect/Dialect.java

@@ -112,11 +112,12 @@ default Set<Class<?>> simpleTypes() {
 	}
 
 	/**
-	 * @return an appropriate {@link InsertWithDefaultValues } for that specific dialect.
+	 * @return an appropriate {@link InsertRenderContext} for that specific dialect.
 	 *         for most of the Dialects the default implementation will be valid, but, for
-	 *         example, in case of {@link SqlServerDialect} it is not
+	 *         example, in case of {@link SqlServerDialect} it is not.
+	 * @since 2.4
 	 */
-	default InsertWithDefaultValues getSqlInsertWithDefaultValues() {
-		return new InsertWithDefaultValues() {};
+	default InsertRenderContext getInsertRenderContext() {
+		return InsertRenderContexts.DEFAULT;
 	}
 }

Diff for: spring-data-relational/src/main/java/org/springframework/data/relational/core/dialect/InsertRenderContext.java

@@ -0,0 +1,16 @@
+package org.springframework.data.relational.core.dialect;
+
+import org.springframework.data.relational.core.sql.Insert;
+import org.springframework.data.relational.core.sql.render.RenderContext;
+
+/**
+ * This interface encapsulates the details about how to process {@link Insert} SQL statement
+ *
+ * @see RenderContext
+ * @author Mikhail Polivakha
+ * @since 2.4
+ */
+public interface InsertRenderContext {
+
+	String getDefaultValuesInsertPart();
+}

Diff for: spring-data-relational/src/main/java/org/springframework/data/relational/core/dialect/InsertRenderContexts.java

@@ -0,0 +1,25 @@
+package org.springframework.data.relational.core.dialect;
+
+/**
+ * In the scope of Insert with default values SQL statement, for example {@literal INSERT INTO SCHEMA.TABLE VALUES
+ * (DEFAULT)} this enum represents the default values part in different {@link Dialect}s
+ *
+ * @author Mikhail Polivakha
+ * @since 2.4
+ */
+public enum InsertRenderContexts implements InsertRenderContext {
+
+	DEFAULT(" VALUES (DEFAULT)"), //
+	MS_SQL_SERVER(" DEFAULT VALUES");
+
+	private final String defaultInsertPart;
+
+	InsertRenderContexts(String defaultInsertPart) {
+		this.defaultInsertPart = defaultInsertPart;
+	}
+
+	public String getDefaultValuesInsertPart() {
+		return defaultInsertPart;
+	}
+
+}

Diff for: spring-data-relational/src/main/java/org/springframework/data/relational/core/dialect/InsertWithDefaultValues.java

@@ -1,17 +1,15 @@
 package org.springframework.data.relational.core.dialect;
 
-import org.springframework.data.relational.core.mapping.InsertDefaultValues;
-
 /**
  * This interface aggregates information about an Insert with default values statement.
+ * 
  * @author Mikhail Polivakha
+ * @since 2.4
  */
 public interface InsertWithDefaultValues {
 
-    /**
-     * @return the part of the sql statement, that follows after <b>INSERT INTO table</b>
-     */
-    default String getDefaultInsertPart() {
-        return InsertDefaultValues.DEFAULT.getDefaultInsertPart();
-    }
-}
+	/**
+	 * @return the part of the sql statement, that follows after <b>INSERT INTO table</b>
+	 */
+	String getDefaultInsertPart();
+}

Diff for: spring-data-relational/src/main/java/org/springframework/data/relational/core/dialect/RenderContextFactory.java

@@ -16,7 +16,6 @@
 package org.springframework.data.relational.core.dialect;
 
 import org.springframework.data.relational.core.sql.IdentifierProcessing;
-import org.springframework.data.relational.core.sql.render.InsertRenderContext;
 import org.springframework.data.relational.core.sql.render.NamingStrategies;
 import org.springframework.data.relational.core.sql.render.RenderContext;
 import org.springframework.data.relational.core.sql.render.RenderNamingStrategy;
@@ -78,19 +77,23 @@ public RenderContext createRenderContext() {
 	static class DialectRenderContext implements RenderContext {
 
 		private final RenderNamingStrategy renderNamingStrategy;
-		private final SelectRenderContext selectRenderContext;
 		private final Dialect renderingDialect;
+		private final SelectRenderContext selectRenderContext;
+		private final InsertRenderContext insertRenderContext;
 
-		DialectRenderContext(RenderNamingStrategy renderNamingStrategy, Dialect renderingDialect, SelectRenderContext selectRenderContext) {
+		DialectRenderContext(RenderNamingStrategy renderNamingStrategy, Dialect renderingDialect,
+				SelectRenderContext selectRenderContext) {
 
 			Assert.notNull(renderNamingStrategy, "RenderNamingStrategy must not be null");
 			Assert.notNull(renderingDialect, "renderingDialect must not be null");
-			Assert.notNull(renderingDialect.getIdentifierProcessing(), "IdentifierProcessing of renderingDialect must not be null");
+			Assert.notNull(renderingDialect.getIdentifierProcessing(),
+					"IdentifierProcessing of renderingDialect must not be null");
 			Assert.notNull(selectRenderContext, "SelectRenderContext must not be null");
 
 			this.renderNamingStrategy = renderNamingStrategy;
 			this.renderingDialect = renderingDialect;
 			this.selectRenderContext = selectRenderContext;
+			this.insertRenderContext = renderingDialect.getInsertRenderContext();
 		}
 
 		/*
@@ -111,6 +114,11 @@ public IdentifierProcessing getIdentifierProcessing() {
 			return renderingDialect.getIdentifierProcessing();
 		}
 
+		@Override
+		public SelectRenderContext getSelect() {
+			return getSelectRenderContext();
+		}
+
 		/*
 		 * (non-Javadoc)
 		 * @see org.springframework.data.relational.core.sql.render.RenderContext#getSelect()
@@ -122,12 +130,7 @@ public SelectRenderContext getSelectRenderContext() {
 
 		@Override
 		public InsertRenderContext getInsertRenderContext() {
-			return new InsertRenderContext() {
-				@Override
-				public String getInsertDefaultValuesPartSQL() {
-					return renderingDialect.getSqlInsertWithDefaultValues().getDefaultInsertPart();
-				}
-			};
+			return insertRenderContext;
 		}
 	}
-}
+}

Diff for: spring-data-relational/src/main/java/org/springframework/data/relational/core/dialect/SqlServerDialect.java

@@ -15,7 +15,6 @@
  */
 package org.springframework.data.relational.core.dialect;
 
-import org.springframework.data.relational.core.mapping.InsertDefaultValues;
 import org.springframework.data.relational.core.sql.IdentifierProcessing;
 import org.springframework.data.relational.core.sql.LockOptions;
 import org.springframework.data.relational.core.sql.render.SelectRenderContext;
@@ -154,12 +153,7 @@ public IdentifierProcessing getIdentifierProcessing() {
 	}
 
 	@Override
-	public InsertWithDefaultValues getSqlInsertWithDefaultValues() {
-		return new InsertWithDefaultValues() {
-			@Override
-			public String getDefaultInsertPart() {
-				return InsertDefaultValues.MS_SQL_SERVER.getDefaultInsertPart();
-			}
-		};
+	public InsertRenderContext getInsertRenderContext() {
+		return InsertRenderContexts.MS_SQL_SERVER;
 	}
 }

Diff for: spring-data-relational/src/main/java/org/springframework/data/relational/core/mapping/InsertDefaultValues.java

@@ -15,7 +15,6 @@
  */
 package org.springframework.data.relational.core.sql.render;
 
-import org.jetbrains.annotations.NotNull;
 import org.springframework.data.relational.core.sql.Column;
 import org.springframework.data.relational.core.sql.Insert;
 import org.springframework.data.relational.core.sql.Into;
@@ -98,7 +97,17 @@ public Delegation doLeave(Visitable segment) {
 		return Delegation.retain();
 	}
 
+	/*
+	 * (non-Javadoc)
+	 * @see org.springframework.data.relational.core.sql.render.PartRenderer#getRenderedPart()
+	 */
+	@Override
+	public CharSequence getRenderedPart() {
+		return builder;
+	}
+
 	private void addInsertValuesIfPresentElseDefault() {
+
 		if (values.length() != 0) {
 			builder.append(" VALUES (").append(values).append(")");
 		} else {
@@ -107,26 +116,18 @@ private void addInsertValuesIfPresentElseDefault() {
 	}
 
 	private void addInsertColumnsIfPresent() {
+
 		if (columns.length() != 0) {
 			builder.append(" (").append(columns).append(")");
 		}
 	}
 
 	private void addInsertWithDefaultValuesToBuilder() {
-		builder.append(renderContext.getInsertRenderContext().getInsertDefaultValuesPartSQL());
+		builder.append(renderContext.getInsertRenderContext().getDefaultValuesInsertPart());
 	}
 
-	/*
-	 * (non-Javadoc)
-	 * @see org.springframework.data.relational.core.sql.render.PartRenderer#getRenderedPart()
-	 */
-	@Override
-	public CharSequence getRenderedPart() {
-		return builder;
-	}
-
-	@NotNull
 	private ColumnVisitor createColumnVisitor(RenderContext context) {
+
 		return new ColumnVisitor(context, false, it -> {
 
 			if (columns.length() != 0) {
@@ -137,8 +138,8 @@ private ColumnVisitor createColumnVisitor(RenderContext context) {
 		});
 	}
 
-	@NotNull
 	private IntoClauseVisitor createIntoClauseVisitor(RenderContext context) {
+
 		return new IntoClauseVisitor(context, it -> {
 
 			if (into.length() != 0) {

Diff for: spring-data-relational/src/main/java/org/springframework/data/relational/core/sql/render/InsertRenderContext.java

@@ -15,6 +15,7 @@
  */
 package org.springframework.data.relational.core.sql.render;
 
+import org.springframework.data.relational.core.dialect.InsertRenderContext;
 import org.springframework.data.relational.core.sql.IdentifierProcessing;
 
 /**
@@ -43,8 +44,17 @@ public interface RenderContext {
 
 	/**
 	 * @return the {@link SelectRenderContext}.
+	 * @deprecated Use {@link #getInsertRenderContext()} instead.
 	 */
-	SelectRenderContext getSelectRenderContext();
+	@Deprecated
+	SelectRenderContext getSelect();
+
+	/**
+	 * @return the {@link SelectRenderContext}.
+	 */
+	default SelectRenderContext getSelectRenderContext() {
+		return getSelect();
+	}
 
 	/**
 	 * @return the {@link InsertRenderContext}