[HUDI-3268] Fix NPE while reading table with Spark datasource

hudi-spark-datasource/hudi-spark-common/src/main/scala/org/apache/hudi/SparkHoodieTableFileIndex.scala

@@ -80,8 +80,10 @@ class SparkHoodieTableFileIndex(spark: SparkSession,
     val nameFieldMap = generateFieldMap(schema)
 
     if (partitionColumns.isPresent) {
-      if (tableConfig.getKeyGeneratorClassName.equalsIgnoreCase(classOf[TimestampBasedKeyGenerator].getName)
-        || tableConfig.getKeyGeneratorClassName.equalsIgnoreCase(classOf[TimestampBasedAvroKeyGenerator].getName)) {
+      // Note that key generator class name could be null
+      val keyGeneratorClassName = tableConfig.getKeyGeneratorClassName
+      if (classOf[TimestampBasedKeyGenerator].getName.equalsIgnoreCase(keyGeneratorClassName)
+        || classOf[TimestampBasedAvroKeyGenerator].getName.equalsIgnoreCase(keyGeneratorClassName)) {
         val partitionFields = partitionColumns.get().map(column => StructField(column, StringType))
         StructType(partitionFields)
       } else {

hudi-spark-datasource/hudi-spark/pom.xml

@@ -466,6 +466,12 @@
       <type>test-jar</type>
       <scope>test</scope>
     </dependency>
+    <dependency>
+      <groupId>org.apache.hudi</groupId>
+      <artifactId>hudi-java-client</artifactId>
+      <version>${project.version}</version>
+      <scope>test</scope>
+    </dependency>
 
     <dependency>
       <groupId>org.scalatest</groupId>

hudi-spark-datasource/hudi-spark/src/test/scala/org/apache/hudi/TestHoodieFileIndex.scala

@@ -17,29 +17,36 @@
 
 package org.apache.hudi
 
-import java.util.Properties
+import org.apache.hadoop.conf.Configuration
 import org.apache.hudi.DataSourceWriteOptions._
+import org.apache.hudi.client.HoodieJavaWriteClient
+import org.apache.hudi.client.common.HoodieJavaEngineContext
 import org.apache.hudi.common.config.HoodieMetadataConfig
+import org.apache.hudi.common.engine.EngineType
+import org.apache.hudi.common.model.{HoodieRecord, HoodieTableType}
 import org.apache.hudi.common.table.HoodieTableMetaClient
 import org.apache.hudi.common.table.view.HoodieTableFileSystemView
-import org.apache.hudi.common.testutils.HoodieTestDataGenerator
+import org.apache.hudi.common.testutils.{HoodieTestDataGenerator, HoodieTestUtils}
+import org.apache.hudi.common.testutils.HoodieTestTable.makeNewCommitTime
 import org.apache.hudi.common.testutils.RawTripTestPayload.recordsToStrings
 import org.apache.hudi.common.util.PartitionPathEncodeUtils
+import org.apache.hudi.common.util.StringUtils.isNullOrEmpty
 import org.apache.hudi.config.HoodieWriteConfig
 import org.apache.hudi.keygen.ComplexKeyGenerator
 import org.apache.hudi.keygen.TimestampBasedAvroKeyGenerator.{Config, TimestampType}
 import org.apache.hudi.testutils.HoodieClientTestBase
 import org.apache.spark.sql.catalyst.InternalRow
-import org.apache.spark.sql.functions.{lit, struct}
 import org.apache.spark.sql.catalyst.expressions.{And, AttributeReference, EqualTo, GreaterThanOrEqual, LessThan, Literal}
 import org.apache.spark.sql.execution.datasources.PartitionDirectory
+import org.apache.spark.sql.functions.{lit, struct}
 import org.apache.spark.sql.types.StringType
-import org.apache.spark.sql.{SaveMode, SparkSession}
+import org.apache.spark.sql.{DataFrameWriter, Row, SaveMode, SparkSession}
 import org.junit.jupiter.api.Assertions.assertEquals
-import org.junit.jupiter.api.BeforeEach
+import org.junit.jupiter.api.{BeforeEach, Test}
 import org.junit.jupiter.params.ParameterizedTest
-import org.junit.jupiter.params.provider.{CsvSource, ValueSource}
+import org.junit.jupiter.params.provider.{Arguments, CsvSource, MethodSource, ValueSource}
 
+import java.util.Properties
 import scala.collection.JavaConversions._
 import scala.collection.JavaConverters._
 
@@ -92,22 +99,25 @@ class TestHoodieFileIndex extends HoodieClientTestBase {
   }
 
   @ParameterizedTest
-  @ValueSource(strings = Array(
-    "org.apache.hudi.keygen.ComplexKeyGenerator",
-    "org.apache.hudi.keygen.SimpleKeyGenerator",
-    "org.apache.hudi.keygen.TimestampBasedKeyGenerator"))
+  @MethodSource(Array("keyGeneratorParameters"))
   def testPartitionSchemaForBuildInKeyGenerator(keyGenerator: String): Unit = {
     val records1 = dataGen.generateInsertsContainsAllPartitions("000", 100)
     val inputDF1 = spark.read.json(spark.sparkContext.parallelize(recordsToStrings(records1), 2))
-    inputDF1.write.format("hudi")
+    val writer: DataFrameWriter[Row] = inputDF1.write.format("hudi")
       .options(commonOpts)
       .option(DataSourceWriteOptions.OPERATION.key, DataSourceWriteOptions.INSERT_OPERATION_OPT_VAL)
-      .option(DataSourceWriteOptions.KEYGENERATOR_CLASS_NAME.key, keyGenerator)
       .option(Config.TIMESTAMP_TYPE_FIELD_PROP, TimestampType.DATE_STRING.name())
       .option(Config.TIMESTAMP_INPUT_DATE_FORMAT_PROP, "yyyy/MM/dd")
       .option(Config.TIMESTAMP_OUTPUT_DATE_FORMAT_PROP, "yyyy-MM-dd")
       .mode(SaveMode.Overwrite)
-      .save(basePath)
+
+    if (isNullOrEmpty(keyGenerator)) {
+      writer.save(basePath)
+    } else {
+      writer.option(DataSourceWriteOptions.KEYGENERATOR_CLASS_NAME.key, keyGenerator)
+        .save(basePath)
+    }
+
     metaClient = HoodieTableMetaClient.reload(metaClient)
     val fileIndex = HoodieFileIndex(spark, metaClient, None, queryOpts)
     assertEquals("partition", fileIndex.partitionSchema.fields.map(_.name).mkString(","))
@@ -132,14 +142,52 @@ class TestHoodieFileIndex extends HoodieClientTestBase {
     assertEquals("partition", fileIndex.partitionSchema.fields.map(_.name).mkString(","))
   }
 
+  @Test
+  def testPartitionSchemaWithoutKeyGenerator(): Unit = {
+    val metaClient = HoodieTestUtils.init(
+      hadoopConf, basePath, HoodieTableType.COPY_ON_WRITE, HoodieTableMetaClient.withPropertyBuilder()
+        .fromMetaClient(this.metaClient)
+        .setRecordKeyFields("_row_key")
+        .setPartitionFields("partition_path")
+        .setTableName("hoodie_test").build())
+    val props = Map(
+      "hoodie.insert.shuffle.parallelism" -> "4",
+      "hoodie.upsert.shuffle.parallelism" -> "4",
+      DataSourceWriteOptions.RECORDKEY_FIELD.key -> "_row_key",
+      DataSourceWriteOptions.PARTITIONPATH_FIELD.key -> "partition_path",
+      DataSourceWriteOptions.PRECOMBINE_FIELD.key -> "timestamp",
+      HoodieWriteConfig.TBL_NAME.key -> "hoodie_test",
+      DataSourceWriteOptions.OPERATION.key -> DataSourceWriteOptions.INSERT_OPERATION_OPT_VAL
+    )
+    val writeConfig = HoodieWriteConfig.newBuilder()
+      .withEngineType(EngineType.JAVA)
+      .withPath(basePath)
+      .withSchema(HoodieTestDataGenerator.TRIP_EXAMPLE_SCHEMA)
+      .withProps(props)
+      .build()
+    val context = new HoodieJavaEngineContext(new Configuration())
+    val writeClient = new HoodieJavaWriteClient(context, writeConfig)
+    val instantTime = makeNewCommitTime()
+
+    val records: java.util.List[HoodieRecord[Nothing]] =
+      dataGen.generateInsertsContainsAllPartitions(instantTime, 100)
+        .asInstanceOf[java.util.List[HoodieRecord[Nothing]]]
+    writeClient.startCommitWithTime(instantTime)
+    writeClient.insert(records, instantTime)
+    metaClient.reloadActiveTimeline()
+
+    val fileIndex = HoodieFileIndex(spark, metaClient, None, queryOpts)
+    assertEquals("partition_path", fileIndex.partitionSchema.fields.map(_.name).mkString(","))
+  }
+
   @ParameterizedTest
   @ValueSource(booleans = Array(true, false))
   def testPartitionPruneWithPartitionEncode(partitionEncode: Boolean): Unit = {
     val props = new Properties()
     props.setProperty(DataSourceWriteOptions.URL_ENCODE_PARTITIONING.key, String.valueOf(partitionEncode))
     initMetaClient(props)
     val partitions = Array("2021/03/08", "2021/03/09", "2021/03/10", "2021/03/11", "2021/03/12")
-    val newDataGen =  new HoodieTestDataGenerator(partitions)
+    val newDataGen = new HoodieTestDataGenerator(partitions)
     val records1 = newDataGen.generateInsertsContainsAllPartitions("000", 100)
     val inputDF1 = spark.read.json(spark.sparkContext.parallelize(recordsToStrings(records1), 2))
     inputDF1.write.format("hudi")
@@ -295,3 +343,14 @@ class TestHoodieFileIndex extends HoodieClientTestBase {
     partitionPaths.map(getFileCountInPartitionPath).sum
   }
 }
+
+object TestHoodieFileIndex {
+  def keyGeneratorParameters(): java.util.stream.Stream[Arguments] = {
+    java.util.stream.Stream.of(
+      Arguments.arguments(null.asInstanceOf[String]),
+      Arguments.arguments("org.apache.hudi.keygen.ComplexKeyGenerator"),
+      Arguments.arguments("org.apache.hudi.keygen.SimpleKeyGenerator"),
+      Arguments.arguments("org.apache.hudi.keygen.TimestampBasedKeyGenerator")
+    )
+  }
+}