[SPARK-19641][SQL] JSON schema inference in DROPMALFORMED mode produces incorrect schema for non-array/object JSONs

sql/core/src/main/scala/org/apache/spark/sql/execution/datasources/json/JsonInferSchema.scala

@@ -25,7 +25,7 @@ import org.apache.spark.rdd.RDD
 import org.apache.spark.sql.catalyst.analysis.TypeCoercion
 import org.apache.spark.sql.catalyst.json.JacksonUtils.nextUntil
 import org.apache.spark.sql.catalyst.json.JSONOptions
-import org.apache.spark.sql.catalyst.util.PermissiveMode
+import org.apache.spark.sql.catalyst.util.{DropMalformedMode, FailFastMode, ParseMode, PermissiveMode}
 import org.apache.spark.sql.types._
 import org.apache.spark.util.Utils
 
@@ -41,7 +41,7 @@ private[sql] object JsonInferSchema {
       json: RDD[T],
       configOptions: JSONOptions,
       createParser: (JsonFactory, T) => JsonParser): StructType = {
-    val shouldHandleCorruptRecord = configOptions.parseMode == PermissiveMode
+    val parseMode = configOptions.parseMode
     val columnNameOfCorruptRecord = configOptions.columnNameOfCorruptRecord
 
     // perform schema inference on each row and merge afterwards
@@ -55,20 +55,24 @@ private[sql] object JsonInferSchema {
             Some(inferField(parser, configOptions))
           }
         } catch {
-          case _: JsonParseException if shouldHandleCorruptRecord =>
-            Some(StructType(Seq(StructField(columnNameOfCorruptRecord, StringType))))
-          case _: JsonParseException =>
-            None
+          case  e @ (_: RuntimeException | _: JsonProcessingException) => parseMode match {
+            case PermissiveMode =>
+              Some(StructType(Seq(StructField(columnNameOfCorruptRecord, StringType))))
+            case DropMalformedMode =>
+              None
+            case FailFastMode =>
+              throw e
+          }
         }
       }
-    }.fold(StructType(Seq()))(
-      compatibleRootType(columnNameOfCorruptRecord, shouldHandleCorruptRecord))
+    }.fold(StructType(Nil))(
+      compatibleRootType(columnNameOfCorruptRecord, parseMode))
 
     canonicalizeType(rootType) match {
       case Some(st: StructType) => st
       case _ =>
         // canonicalizeType erases all empty structs, including the only one we want to keep
-        StructType(Seq())
+        StructType(Nil)
     }
   }
 
@@ -217,26 +221,43 @@ private[sql] object JsonInferSchema {
     }
   }
 
+  private def withParseMode(
+      struct: StructType,
+      other: DataType,
+      columnNameOfCorruptRecords: String,
+      parseMode: ParseMode) = parseMode match {
+    // If we see any other data type at the root level, we get records that cannot be
+    // parsed. So, we use the struct as the data type and add the corrupt field to the schema.
+    case PermissiveMode => withCorruptField(struct, columnNameOfCorruptRecords)
+
+    // If corrupt record handling is disabled we retain the valid schema and discard the other.
+    case DropMalformedMode => struct
+
+    // If `other` is not struct type, consider it as malformed one and throws an exception.
+    case FailFastMode =>
+      throw new RuntimeException("Failed to infer a common schema. Struct types are expected" +
+        s" but ${other.catalogString} was found.")
+  }
+
   /**
    * Remove top-level ArrayType wrappers and merge the remaining schemas
    */
   private def compatibleRootType(
       columnNameOfCorruptRecords: String,
-      shouldHandleCorruptRecord: Boolean): (DataType, DataType) => DataType = {
+      parseMode: ParseMode): (DataType, DataType) => DataType = {
     // Since we support array of json objects at the top level,
     // we need to check the element type and find the root level data type.
     case (ArrayType(ty1, _), ty2) =>
-      compatibleRootType(columnNameOfCorruptRecords, shouldHandleCorruptRecord)(ty1, ty2)
+      compatibleRootType(columnNameOfCorruptRecords, parseMode)(ty1, ty2)
     case (ty1, ArrayType(ty2, _)) =>
-      compatibleRootType(columnNameOfCorruptRecords, shouldHandleCorruptRecord)(ty1, ty2)
-    // If we see any other data type at the root level, we get records that cannot be
-    // parsed. So, we use the struct as the data type and add the corrupt field to the schema.
+      compatibleRootType(columnNameOfCorruptRecords, parseMode)(ty1, ty2)
+    // Discard null/empty documents
     case (struct: StructType, NullType) => struct
     case (NullType, struct: StructType) => struct
-    case (struct: StructType, o) if !o.isInstanceOf[StructType] && shouldHandleCorruptRecord =>
-      withCorruptField(struct, columnNameOfCorruptRecords)
-    case (o, struct: StructType) if !o.isInstanceOf[StructType] && shouldHandleCorruptRecord =>
-      withCorruptField(struct, columnNameOfCorruptRecords)
+    case (struct: StructType, o) if !o.isInstanceOf[StructType] =>
+      withParseMode(struct, o, columnNameOfCorruptRecords, parseMode)
+    case (o, struct: StructType) if !o.isInstanceOf[StructType] =>
+      withParseMode(struct, o, columnNameOfCorruptRecords, parseMode)
     // If we get anything else, we call compatibleType.
     // Usually, when we reach here, ty1 and ty2 are two StructTypes.
     case (ty1, ty2) => compatibleType(ty1, ty2)

sql/core/src/test/scala/org/apache/spark/sql/execution/datasources/json/JsonSuite.scala

@@ -1041,7 +1041,6 @@ class JsonSuite extends QueryTest with SharedSQLContext with TestJsonData {
       spark.read
         .option("mode", "FAILFAST")
         .json(corruptRecords)
-        .collect()
     }
     assert(exceptionOne.getMessage.contains("JsonParseException"))
 
@@ -1082,6 +1081,18 @@ class JsonSuite extends QueryTest with SharedSQLContext with TestJsonData {
     assert(jsonDFTwo.schema === schemaTwo)
   }
 
+  test("SPARK-19641: Additional corrupt records: DROPMALFORMED mode") {
+    val schema = new StructType().add("dummy", StringType)
+    // `DROPMALFORMED` mode should skip corrupt records
+    val jsonDF = spark.read
+      .option("mode", "DROPMALFORMED")
+      .json(additionalCorruptRecords)
+    checkAnswer(
+      jsonDF,
+      Row("test"))
+    assert(jsonDF.schema === schema)
+  }
+
   test("Corrupt records: PERMISSIVE mode, without designated column for malformed records") {
     val schema = StructType(
       StructField("a", StringType, true) ::
@@ -1882,6 +1893,24 @@ class JsonSuite extends QueryTest with SharedSQLContext with TestJsonData {
     }
   }
 
+  test("SPARK-19641: Handle multi-line corrupt documents (DROPMALFORMED)") {
+    withTempPath { dir =>
+      val path = dir.getCanonicalPath
+      val corruptRecordCount = additionalCorruptRecords.count().toInt
+      assert(corruptRecordCount === 5)
+
+      additionalCorruptRecords
+        .toDF("value")
+        // this is the minimum partition count that avoids hash collisions
+        .repartition(corruptRecordCount * 4, F.hash($"value"))
+        .write
+        .text(path)
+
+      val jsonDF = spark.read.option("wholeFile", true).option("mode", "DROPMALFORMED").json(path)
+      checkAnswer(jsonDF, Seq(Row("test")))
+    }
+  }
+
   test("SPARK-18352: Handle multi-line corrupt documents (FAILFAST)") {
     withTempPath { dir =>
       val path = dir.getCanonicalPath
@@ -1903,9 +1932,8 @@ class JsonSuite extends QueryTest with SharedSQLContext with TestJsonData {
           .option("wholeFile", true)
           .option("mode", "FAILFAST")
           .json(path)
-          .collect()
       }
-      assert(exceptionOne.getMessage.contains("Failed to parse a value"))
+      assert(exceptionOne.getMessage.contains("Failed to infer a common schema"))
 
       val exceptionTwo = intercept[SparkException] {
         spark.read