raminqaf commented on code in PR #29617:
URL: https://github.com/apache/flink/pull/29617#discussion_r4401650697
##########
flink-table/flink-table-api-java/src/main/java/org/apache/flink/table/api/internal/BaseExpressions.java:
##########
@@ -1481,6 +1483,70 @@ public OutType tryParseXml(InType forceArray) {
unresolvedCall(TRY_PARSE_XML, toExpr(),
objectToExpression(forceArray)));
}
+ /**
+ * Returns the value of a {@link DataTypes#VARIANT()} at a path as a {@link
+ * DataTypes#VARIANT()}. If the variant or the path is {@code NULL}, or
nothing is at the path,
+ * {@code NULL} is returned. A variant null at the path stays a variant
null, which is not
+ * {@code NULL}.
+ *
+ * <p>This is a shortcut for {@code variantGet(path,
DataTypes.VARIANT())}. See {@link
+ * #variantGet(Object, DataType)}.
+ */
+ public OutType variantGet(InType path) {
+ return toApiSpecificExpression(
+ unresolvedCall(VARIANT_GET, toExpr(),
objectToExpression(path)));
+ }
+
+ /**
+ * Returns the value of a {@link DataTypes#VARIANT()} at a path such as
{@code $.items[0].qty},
+ * cast to the given type. Array indices start at 0. If the variant or the
path is {@code NULL},
+ * or nothing is at the path, {@code NULL} is returned. If the value
cannot be cast to the type,
+ * an error is thrown. To return {@code NULL} instead, use {@link
#tryVariantGet(Object,
+ * DataType)}.
+ *
+ * <p>The value is cast like {@code CAST}, so a variant null gives {@code
NULL} unless the type
+ * is {@link DataTypes#VARIANT()}. See the SQL function {@code
VARIANT_GET} for the path syntax.
+ *
+ * @param returnType the type of the result, always nullable. Only its
logical type is used.
Review Comment:
Done
##########
flink-table/flink-table-common/src/main/java/org/apache/flink/table/types/inference/strategies/VariantGetTypeStrategy.java:
##########
@@ -0,0 +1,83 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements. See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. The ASF licenses this file
+ * to you 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
+ *
+ * http://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.apache.flink.table.types.inference.strategies;
+
+import org.apache.flink.annotation.Internal;
+import org.apache.flink.table.api.DataTypes;
+import org.apache.flink.table.api.ValidationException;
+import org.apache.flink.table.types.DataType;
+import org.apache.flink.table.types.inference.CallContext;
+import org.apache.flink.table.types.inference.TypeStrategy;
+import org.apache.flink.table.types.logical.LogicalType;
+import org.apache.flink.table.types.logical.VariantType;
+import org.apache.flink.table.types.logical.utils.LogicalTypeCasts;
+
+import java.util.Optional;
+
+/**
+ * Type strategy for {@code VARIANT_GET(variant, path [, type])} and {@code
TRY_VARIANT_GET}.
+ *
+ * <p>The result is the type named by the {@code type} literal, or {@code
VARIANT} without one. It
+ * is always nullable, because a path that points at nothing gives {@code
NULL}.
+ */
+@Internal
+public final class VariantGetTypeStrategy implements TypeStrategy {
+
+ static final int ARG_TYPE = 2;
+
+ @Override
+ public Optional<DataType> inferType(final CallContext callContext) {
+ if (callContext.getArgumentDataTypes().size() <= ARG_TYPE) {
+ return Optional.of(DataTypes.VARIANT().nullable());
+ }
+ return Optional.of(resolveTargetType(callContext));
+ }
+
+ /**
+ * Resolves the {@code type} literal to a nullable type that {@code
VARIANT} can be cast to.
+ *
+ * @throws ValidationException if the literal is not a type or names a
type that {@code VARIANT}
+ * cannot be cast to
+ */
+ static DataType resolveTargetType(final CallContext callContext) {
+ // The input strategy only accepts a non-null literal.
+ final String typeString =
+ callContext
+ .getArgumentValue(ARG_TYPE, String.class)
+ .orElseThrow(IllegalStateException::new);
+ final DataType type;
+ try {
+ type = callContext.getDataTypeFactory().createDataType(typeString);
+ } catch (RuntimeException e) {
+ throw new ValidationException(
+ String.format(
+ "Invalid type '%s' for %s: %s",
+ typeString, callContext.getName(), e.getMessage()),
+ e);
+ }
+ final LogicalType logicalType = type.getLogicalType();
Review Comment:
added
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