HHH-18780 Use column type information to generate union subclass null casts

hibernate-community-dialects/src/main/java/org/hibernate/community/dialect/PostgreSQLLegacyDialect.java

@@ -55,6 +55,8 @@
 import org.hibernate.exception.spi.ViolatedConstraintNameExtractor;
 import org.hibernate.internal.util.JdbcExceptionHelper;
 import org.hibernate.metamodel.mapping.EntityMappingType;
+import org.hibernate.metamodel.mapping.SqlExpressible;
+import org.hibernate.metamodel.mapping.SqlTypedMapping;
 import org.hibernate.metamodel.spi.RuntimeModelCreationContext;
 import org.hibernate.procedure.internal.PostgreSQLCallableStatementSupport;
 import org.hibernate.procedure.spi.CallableStatementSupport;
@@ -217,6 +219,7 @@ protected String castType(int sqlTypeCode) {
 			case NCHAR:
 			case VARCHAR:
 			case NVARCHAR:
+				return "varchar";
 			case LONG32VARCHAR:
 			case LONG32NVARCHAR:
 				return "text";
@@ -872,6 +875,14 @@ public String getSelectClauseNullString(int sqlType, TypeConfiguration typeConfi
 		return "cast(null as " + typeConfiguration.getDdlTypeRegistry().getDescriptor( sqlType ).getRawTypeName() + ")";
 	}
 
+	@Override
+	public String getSelectClauseNullString(SqlTypedMapping sqlType, TypeConfiguration typeConfiguration) {
+		final String castTypeName = typeConfiguration.getDdlTypeRegistry()
+				.getDescriptor( sqlType.getJdbcMapping().getJdbcType().getDdlTypeCode() )
+				.getCastTypeName( sqlType.toSize(), (SqlExpressible) sqlType.getJdbcMapping(), typeConfiguration.getDdlTypeRegistry() );
+		return "cast(null as " + castTypeName + ")";
+	}
+
 	@Override
 	public boolean supportsCommentOn() {
 		return true;

hibernate-core/src/main/java/org/hibernate/dialect/Dialect.java

@@ -116,6 +116,7 @@
 import org.hibernate.mapping.Table;
 import org.hibernate.mapping.UserDefinedType;
 import org.hibernate.metamodel.mapping.EntityMappingType;
+import org.hibernate.metamodel.mapping.SqlTypedMapping;
 import org.hibernate.metamodel.spi.RuntimeModelCreationContext;
 import org.hibernate.persister.entity.Lockable;
 import org.hibernate.persister.entity.mutation.EntityMutationTarget;
@@ -3115,11 +3116,31 @@
 	 * @param sqlType The {@link Types} type code.
 	 * @param typeConfiguration The type configuration
 	 * @return The appropriate select clause value fragment.
+	 * @deprecated Use {@link #getSelectClauseNullString(SqlTypedMapping, TypeConfiguration)} instead
 	 */
+	@Deprecated(forRemoval = true)
 	public String getSelectClauseNullString(int sqlType, TypeConfiguration typeConfiguration) {
 		return "null";
 	}
 
+	/**
+	 * Given a type mapping, return the expression
+	 * for a literal null value of that type, to use in a {@code select}
+	 * clause.
+	 * <p>
+	 * The {@code select} query will be an element of a {@code UNION}
+	 * or {@code UNION ALL}.
+	 *
+	 * @implNote Some databases require an explicit type cast.
+	 *
+	 * @param sqlTypeMapping The type mapping.
+	 * @param typeConfiguration The type configuration
+	 * @return The appropriate select clause value fragment.
+	 */
+	public String getSelectClauseNullString(SqlTypedMapping sqlTypeMapping, TypeConfiguration typeConfiguration) {
+		return getSelectClauseNullString( sqlTypeMapping.getJdbcMapping().getJdbcType().getDdlTypeCode(), typeConfiguration );
+	}
+
 	/**
 	 * Does this dialect support {@code UNION ALL}?
 	 *
@@ -3217,7 +3238,7 @@
 	 *         {@code is false}, or {@code false} if it does not. The
 	 *         default is {@code is false}.
 	 */
 	public boolean supportsIsTrue() {
 		return false;
 	}
 

hibernate-core/src/main/java/org/hibernate/dialect/DialectDelegateWrapper.java

@@ -55,6 +55,7 @@
 import org.hibernate.mapping.Table;
 import org.hibernate.mapping.UserDefinedType;
 import org.hibernate.metamodel.mapping.EntityMappingType;
+import org.hibernate.metamodel.mapping.SqlTypedMapping;
 import org.hibernate.metamodel.spi.RuntimeModelCreationContext;
 import org.hibernate.persister.entity.Lockable;
 import org.hibernate.persister.entity.mutation.EntityMutationTarget;
@@ -731,6 +732,11 @@ public String getSelectClauseNullString(int sqlType, TypeConfiguration typeConfi
 		return wrapped.getSelectClauseNullString( sqlType, typeConfiguration );
 	}
 
+	@Override
+	public String getSelectClauseNullString(SqlTypedMapping sqlTypeMapping, TypeConfiguration typeConfiguration) {
+		return wrapped.getSelectClauseNullString( sqlTypeMapping, typeConfiguration );
+	}
+
 	@Override
 	public boolean supportsUnionAll() {
 		return wrapped.supportsUnionAll();

hibernate-core/src/main/java/org/hibernate/dialect/PostgreSQLDialect.java

@@ -52,6 +52,8 @@
 import org.hibernate.exception.spi.ViolatedConstraintNameExtractor;
 import org.hibernate.internal.util.JdbcExceptionHelper;
 import org.hibernate.metamodel.mapping.EntityMappingType;
+import org.hibernate.metamodel.mapping.SqlExpressible;
+import org.hibernate.metamodel.mapping.SqlTypedMapping;
 import org.hibernate.metamodel.spi.RuntimeModelCreationContext;
 import org.hibernate.persister.entity.mutation.EntityMutationTarget;
 import org.hibernate.procedure.internal.PostgreSQLCallableStatementSupport;
@@ -247,6 +249,7 @@ protected String castType(int sqlTypeCode) {
 			case NCHAR:
 			case VARCHAR:
 			case NVARCHAR:
+				return "varchar";
 			case LONG32VARCHAR:
 			case LONG32NVARCHAR:
 				return "text";
@@ -939,6 +942,17 @@ public String getSelectClauseNullString(int sqlType, TypeConfiguration typeConfi
 		return "cast(null as " + typeConfiguration.getDdlTypeRegistry().getDescriptor( sqlType ).getRawTypeName() + ")";
 	}
 
+	@Override
+	public String getSelectClauseNullString(SqlTypedMapping sqlType, TypeConfiguration typeConfiguration) {
+		final DdlTypeRegistry ddlTypeRegistry = typeConfiguration.getDdlTypeRegistry();
+		final String castTypeName = ddlTypeRegistry
+				.getDescriptor( sqlType.getJdbcMapping().getJdbcType().getDdlTypeCode() )
+				.getCastTypeName( sqlType.toSize(), (SqlExpressible) sqlType.getJdbcMapping(), ddlTypeRegistry );
+		// PostgreSQL assumes a plain null literal in the select statement to be of type text,
+		// which can lead to issues in e.g. the union subclass strategy, so do a cast
+		return "cast(null as " + castTypeName + ")";
+	}
+
 	@Override
 	public String quoteCollation(String collation) {
 		return '\"' + collation + '\"';

hibernate-core/src/main/java/org/hibernate/dialect/function/array/OracleArrayToStringFunction.java

@@ -8,19 +8,21 @@
 
 import java.util.List;
 
+import org.hibernate.metamodel.mapping.JdbcMappingContainer;
 import org.hibernate.query.ReturnableType;
-import org.hibernate.query.sqm.function.AbstractSqmSelfRenderingFunctionDescriptor;
-import org.hibernate.query.sqm.produce.function.ArgumentTypesValidator;
-import org.hibernate.query.sqm.produce.function.StandardArgumentsValidators;
-import org.hibernate.query.sqm.produce.function.StandardFunctionArgumentTypeResolvers;
+import org.hibernate.query.sqm.function.SelfRenderingOrderedSetAggregateFunctionSqlAstExpression;
+import org.hibernate.sql.ast.Clause;
 import org.hibernate.sql.ast.SqlAstTranslator;
 import org.hibernate.sql.ast.spi.SqlAppender;
 import org.hibernate.sql.ast.tree.SqlAstNode;
 import org.hibernate.sql.ast.tree.expression.Expression;
+import org.hibernate.sql.ast.tree.expression.FunctionExpression;
+import org.hibernate.sql.ast.tree.predicate.Predicate;
+import org.hibernate.sql.ast.tree.select.SortSpecification;
+import org.hibernate.type.SqlTypes;
 import org.hibernate.type.spi.TypeConfiguration;
 
-import static org.hibernate.query.sqm.produce.function.FunctionParameterType.ANY;
-import static org.hibernate.query.sqm.produce.function.FunctionParameterType.INTEGER;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * Oracle array_to_string function.
@@ -37,22 +39,89 @@ public void render(
 			List<? extends SqlAstNode> sqlAstArguments,
 			ReturnableType<?> returnType,
 			SqlAstTranslator<?> walker) {
-		final String arrayTypeName = DdlTypeHelper.getTypeName(
-				( (Expression) sqlAstArguments.get( 0 ) ).getExpressionType(),
-				walker.getSessionFactory().getTypeConfiguration()
-		);
-		sqlAppender.append( arrayTypeName );
-		sqlAppender.append( "_to_string(" );
-		sqlAstArguments.get( 0 ).accept( walker );
-		sqlAppender.append( ',' );
-		sqlAstArguments.get( 1 ).accept( walker );
-		if ( sqlAstArguments.size() > 2 ) {
+		final Expression arrayExpression = (Expression) sqlAstArguments.get( 0 );
+		final JdbcMappingContainer expressionType = (arrayExpression).getExpressionType();
+		if ( arrayExpression instanceof SelfRenderingOrderedSetAggregateFunctionSqlAstExpression
+				&& ArrayAggFunction.FUNCTION_NAME.equals( ( (FunctionExpression) arrayExpression ).getFunctionName() ) ) {
+			final SelfRenderingOrderedSetAggregateFunctionSqlAstExpression functionExpression
+					= (SelfRenderingOrderedSetAggregateFunctionSqlAstExpression) arrayExpression;
+			// When the array argument is an aggregate expression, we access its contents directly
+			final Expression arrayElementExpression = (Expression) functionExpression.getArguments().get( 0 );
+			final @Nullable Expression defaultExpression =
+					sqlAstArguments.size() > 2 ? (Expression) sqlAstArguments.get( 2 ) : null;
+			final List<SortSpecification> withinGroup = functionExpression.getWithinGroup();
+			final Predicate filter = functionExpression.getFilter();
+
+			sqlAppender.append( "listagg(" );
+			if ( filter != null ) {
+				sqlAppender.appendSql( "case when " );
+				walker.getCurrentClauseStack().push( Clause.WHERE );
+				filter.accept( walker );
+				walker.getCurrentClauseStack().pop();
+				sqlAppender.appendSql( " then " );
+			}
+			if ( defaultExpression != null ) {
+				sqlAppender.append( "coalesce(" );
+			}
+			arrayElementExpression.accept( walker );
+			if ( defaultExpression != null ) {
+				sqlAppender.append( ',' );
+				defaultExpression.accept( walker );
+				sqlAppender.append( ')' );
+			}
+			if ( filter != null ) {
+				sqlAppender.appendSql( " else null end" );
+			}
 			sqlAppender.append( ',' );
-			sqlAstArguments.get( 2 ).accept( walker );
+			sqlAstArguments.get( 1 ).accept( walker );
+			sqlAppender.appendSql( ')' );
+
+			if ( withinGroup != null && !withinGroup.isEmpty() ) {
+				walker.getCurrentClauseStack().push( Clause.WITHIN_GROUP );
+				sqlAppender.appendSql( " within group (order by " );
+				withinGroup.get( 0 ).accept( walker );
+				for ( int i = 1; i < withinGroup.size(); i++ ) {
+					sqlAppender.appendSql( ',' );
+					withinGroup.get( i ).accept( walker );
+				}
+				sqlAppender.appendSql( ')' );
+				walker.getCurrentClauseStack().pop();
+			}
+		}
+		else if ( expressionType.getSingleJdbcMapping().getJdbcType().getDefaultSqlTypeCode() ==  SqlTypes.JSON ) {
+			sqlAppender.append( "(select listagg(" );
+			if ( sqlAstArguments.size() > 2 ) {
+				sqlAppender.append( "coalesce(t.v," );
+				sqlAstArguments.get( 2 ).accept( walker );
+				sqlAppender.append( ")," );
+			}
+			else {
+				sqlAppender.append( "t.v," );
+			}
+
+			sqlAstArguments.get( 1 ).accept( walker );
+			sqlAppender.append( ") from json_table(" );
+			sqlAstArguments.get( 0 ).accept( walker );
+			sqlAppender.append( ",'$[*]' columns (v path '$')) t)" );
 		}
 		else {
-			sqlAppender.append( ",null" );
+			final String arrayTypeName = DdlTypeHelper.getTypeName(
+					expressionType,
+					walker.getSessionFactory().getTypeConfiguration()
+			);
+			sqlAppender.append( arrayTypeName );
+			sqlAppender.append( "_to_string(" );
+			sqlAstArguments.get( 0 ).accept( walker );
+			sqlAppender.append( ',' );
+			sqlAstArguments.get( 1 ).accept( walker );
+			if ( sqlAstArguments.size() > 2 ) {
+				sqlAppender.append( ',' );
+				sqlAstArguments.get( 2 ).accept( walker );
+			}
+			else {
+				sqlAppender.append( ",null" );
+			}
+			sqlAppender.append( ')' );
 		}
-		sqlAppender.append( ')' );
 	}
 }

hibernate-core/src/main/java/org/hibernate/metamodel/mapping/SqlTypedMapping.java

@@ -8,17 +8,20 @@
 
 import org.hibernate.engine.jdbc.Size;
 
+import org.checkerframework.checker.nullness.qual.Nullable;
+
 /**
  * Models the type of a thing that can be used as an expression in a SQL query
  *
  * @author Christian Beikov
  */
 public interface SqlTypedMapping {
+	@Nullable
 	String getColumnDefinition();
-	Long getLength();
-	Integer getPrecision();
-	Integer getScale();
-	Integer getTemporalPrecision();
+	@Nullable Long getLength();
+	@Nullable Integer getPrecision();
+	@Nullable Integer getScale();
+	@Nullable Integer getTemporalPrecision();
 	default boolean isLob() {
 		return getJdbcMapping().getJdbcType().isLob();
 	}

hibernate-core/src/main/java/org/hibernate/metamodel/mapping/internal/SqlTypedMappingImpl.java

@@ -9,24 +9,30 @@
 import org.hibernate.metamodel.mapping.JdbcMapping;
 import org.hibernate.metamodel.mapping.SqlTypedMapping;
 
+import org.checkerframework.checker.nullness.qual.Nullable;
+
 /**
  * @author Christian Beikov
  */
 public class SqlTypedMappingImpl implements SqlTypedMapping {
 
-	private final String columnDefinition;
-	private final Long length;
-	private final Integer precision;
-	private final Integer scale;
-	private final Integer temporalPrecision;
+	private final @Nullable String columnDefinition;
+	private final @Nullable Long length;
+	private final @Nullable Integer precision;
+	private final @Nullable Integer scale;
+	private final @Nullable Integer temporalPrecision;
 	private final JdbcMapping jdbcMapping;
 
+	public SqlTypedMappingImpl(JdbcMapping jdbcMapping) {
+		this( null, null, null, null, null, jdbcMapping );
+	}
+
 	public SqlTypedMappingImpl(
-			String columnDefinition,
-			Long length,
-			Integer precision,
-			Integer scale,
-			Integer temporalPrecision,
+			@Nullable String columnDefinition,
+			@Nullable Long length,
+			@Nullable Integer precision,
+			@Nullable Integer scale,
+			@Nullable Integer temporalPrecision,
 			JdbcMapping jdbcMapping) {
 		// Save memory by using interned strings. Probability is high that we have multiple duplicate strings
 		this.columnDefinition = columnDefinition == null ? null : columnDefinition.intern();
@@ -38,27 +44,27 @@ public SqlTypedMappingImpl(
 	}
 
 	@Override
-	public String getColumnDefinition() {
+	public @Nullable String getColumnDefinition() {
 		return columnDefinition;
 	}
 
 	@Override
-	public Long getLength() {
+	public @Nullable Long getLength() {
 		return length;
 	}
 
 	@Override
-	public Integer getPrecision() {
+	public @Nullable Integer getPrecision() {
 		return precision;
 	}
 
 	@Override
-	public Integer getTemporalPrecision() {
+	public @Nullable Integer getTemporalPrecision() {
 		return temporalPrecision;
 	}
 
 	@Override
-	public Integer getScale() {
+	public @Nullable Integer getScale() {
 		return scale;
 	}