(paimon) branch master updated: [format] Report unresolvable JSON string casts instead of a bare NPE (#9588)

[lzljs3620320]

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JingsongLi pushed a commit to branch master
in repository https://gitbox.apache.org/repos/asf/paimon.git


The following commit(s) were added to refs/heads/master by this push:
     new 09e7a7a56b [format] Report unresolvable JSON string casts instead of a 
bare NPE (#9588)
09e7a7a56b is described below

commit 09e7a7a56b0361d9454ef994542043a3deaab0a8
Author: YangJie <yangji...@baidu.com>
AuthorDate: Fri Sep 4 03:22:37 2026 -0400

    [format] Report unresolvable JSON string casts instead of a bare NPE (#9588)
---
 .../apache/paimon/format/json/JsonFileReader.java  |  8 +++--
 .../paimon/format/json/JsonFileFormatTest.java     | 35 ++++++++++++++++++++++
 2 files changed, 41 insertions(+), 2 deletions(-)

diff --git 
a/paimon-format/src/main/java/org/apache/paimon/format/json/JsonFileReader.java 
b/paimon-format/src/main/java/org/apache/paimon/format/json/JsonFileReader.java
index d5ecf3dc8f..5004396871 100644
--- 
a/paimon-format/src/main/java/org/apache/paimon/format/json/JsonFileReader.java
+++ 
b/paimon-format/src/main/java/org/apache/paimon/format/json/JsonFileReader.java
@@ -234,9 +234,13 @@ public class JsonFileReader extends AbstractTextFileReader 
{
                 case VARCHAR:
                     return BinaryString.fromString(str);
                 default:
-                    BinaryString binaryString = BinaryString.fromString(str);
                     CastExecutor cast = 
CastExecutors.resolve(DataTypes.STRING(), dataType);
-                    return cast.cast(binaryString);
+                    if (cast == null) {
+                        // resolve returns null when no rule matches the 
target type.
+                        throw new UnsupportedOperationException(
+                                "Unsupported data type for JSON format: " + 
dataType);
+                    }
+                    return cast.cast(BinaryString.fromString(str));
             }
         } catch (Exception e) {
             return handleParseError(e);
diff --git 
a/paimon-format/src/test/java/org/apache/paimon/format/json/JsonFileFormatTest.java
 
b/paimon-format/src/test/java/org/apache/paimon/format/json/JsonFileFormatTest.java
index 56485da501..5b79fab95b 100644
--- 
a/paimon-format/src/test/java/org/apache/paimon/format/json/JsonFileFormatTest.java
+++ 
b/paimon-format/src/test/java/org/apache/paimon/format/json/JsonFileFormatTest.java
@@ -36,18 +36,21 @@ import org.apache.paimon.fs.Path;
 import org.apache.paimon.fs.PositionOutputStream;
 import org.apache.paimon.options.Options;
 import org.apache.paimon.reader.RecordReader;
+import org.apache.paimon.types.DataType;
 import org.apache.paimon.types.DataTypes;
 import org.apache.paimon.types.RowType;
 
 import org.junit.jupiter.api.Test;
 
 import java.io.IOException;
+import java.nio.charset.StandardCharsets;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.List;
 import java.util.UUID;
 
 import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.assertThatThrownBy;
 import static org.junit.jupiter.api.Assertions.assertThrows;
 
 /** Test for {@link JsonFileFormat}. */
@@ -69,6 +72,38 @@ public class JsonFileFormatTest extends FormatReadWriteTest {
         return HadoopCompressionType.NONE.value();
     }
 
+    @Test
+    public void testUnresolvableCastFailsWithClearMessage() throws Exception {
+        JsonFileFormat format =
+                new JsonFileFormat(new FileFormatFactory.FormatContext(new 
Options(), 1024, 1024));
+
+        Path testFile = new Path(parent, "unresolvable_cast_" + 
UUID.randomUUID() + ".json");
+        try (PositionOutputStream out = fileIO.newOutputStream(testFile, 
true)) {
+            out.write("{\"f0\":{\"a\":1}}".getBytes(StandardCharsets.UTF_8));
+        }
+
+        // MULTISET has no cast rule from STRING. A format table is created 
without going
+        // through SchemaValidation, so such a column reaches the reader.
+        RowType rowType =
+                RowType.of(
+                        new DataType[] 
{DataTypes.MULTISET(DataTypes.STRING())},
+                        new String[] {"f0"});
+
+        try (RecordReader<InternalRow> reader =
+                format.createReaderFactory(rowType, rowType, new ArrayList<>())
+                        .createReader(
+                                new FormatReaderContext(
+                                        fileIO,
+                                        testFile,
+                                        fileIO.getFileSize(testFile),
+                                        null,
+                                        null))) {
+            assertThatThrownBy(() -> reader.forEachRemaining(row -> {}))
+                    
.hasRootCauseInstanceOf(UnsupportedOperationException.class)
+                    .hasRootCauseMessage("Unsupported data type for JSON 
format: MULTISET<STRING>");
+        }
+    }
+
     @Test
     public void testIgnoreParseErrorsEnabled() throws IOException {
         RowType rowType = DataTypes.ROW(DataTypes.INT().notNull(), 
DataTypes.STRING());