improve error msg

Author: gengliangwang

sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/Cast.scala

@@ -262,6 +262,11 @@ abstract class CastBase extends UnaryExpression with TimeZoneAwareExpression wit
    */
   def canCast(from: DataType, to: DataType): Boolean
 
+  /**
+   * Returns the error message if casting from one type to another one is invalid.
+   */
+  def typeCheckFailureMessage: String
+
   override def toString: String = {
     val ansi = if (ansiEnabled) "ansi_" else ""
     s"${ansi}cast($child as ${dataType.simpleString})"
@@ -271,8 +276,7 @@ abstract class CastBase extends UnaryExpression with TimeZoneAwareExpression wit
     if (canCast(child.dataType, dataType)) {
       TypeCheckResult.TypeCheckSuccess
     } else {
-      TypeCheckResult.TypeCheckFailure(
-        s"cannot cast ${child.dataType.catalogString} to ${dataType.catalogString}")
+      TypeCheckResult.TypeCheckFailure(typeCheckFailureMessage)
     }
   }
 
@@ -1755,6 +1759,12 @@ case class Cast(child: Expression, dataType: DataType, timeZoneId: Option[String
   } else {
     Cast.canCast(from, to)
   }
+
+  override def typeCheckFailureMessage: String = if (ansiEnabled) {
+    AnsiCast.typeCheckFailureMessage(child.dataType, dataType, SQLConf.ANSI_ENABLED.key, "false")
+  } else {
+    s"cannot cast ${child.dataType.catalogString} to ${dataType.catalogString}"
+  }
 }
 
 /**
@@ -1774,6 +1784,14 @@ case class AnsiCast(child: Expression, dataType: DataType, timeZoneId: Option[St
   override protected val ansiEnabled: Boolean = true
 
   override def canCast(from: DataType, to: DataType): Boolean = AnsiCast.canCast(from, to)
+
+  // For now, this expression is only used in table insertion.
+  // If there are more scenarios for this expression, we should update the error message on type
+  // check failure.
+  override def typeCheckFailureMessage: String =
+    AnsiCast.typeCheckFailureMessage(child.dataType, dataType,
+      SQLConf.STORE_ASSIGNMENT_POLICY.key, SQLConf.StoreAssignmentPolicy.LEGACY.toString)
+
 }
 
 object AnsiCast {
@@ -1876,6 +1894,35 @@ object AnsiCast {
 
     case _ => false
   }
+
+  def typeCheckFailureMessage(
+      from: DataType,
+      to: DataType,
+      fallbackConfKey: String,
+      fallbackConfValue: String): String =
+    (from, to) match {
+      case (_: NumericType, TimestampType) =>
+        // scalastyle:off line.size.limit
+        s"""
+           | cannot cast ${from.catalogString} to ${to.catalogString}.
+           | To convert values from ${from.catalogString} to ${to.catalogString}, you can use functions TIMESTAMP_SECONDS/TIMESTAMP_MILLIS/TIMESTAMP_MICROS instead.
+           |""".stripMargin
+
+      case (_: ArrayType, StringType) =>
+        s"""
+           | cannot cast ${from.catalogString} to ${to.catalogString} with ANSI mode on.
+           | If you have to cast ${from.catalogString} to ${to.catalogString}, you can use the function array_join or set $fallbackConfKey as $fallbackConfValue.
+           |""".stripMargin
+
+      case _ if Cast.canCast(from, to) =>
+        s"""
+           | cannot cast ${from.catalogString} to ${to.catalogString} with ANSI mode on.
+           | If you have to cast ${from.catalogString} to ${to.catalogString}, you can set $fallbackConfKey as $fallbackConfValue.
+           |""".stripMargin
+
+      case _ => s"cannot cast ${from.catalogString} to ${to.catalogString}"
+      // scalastyle:on line.size.limit
+    }
 }
 
 /**

sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/expressions/CastSuite.scala

@@ -25,6 +25,7 @@ import scala.collection.parallel.immutable.ParVector
 import org.apache.spark.SparkFunSuite
 import org.apache.spark.sql.Row
 import org.apache.spark.sql.catalyst.InternalRow
+import org.apache.spark.sql.catalyst.analysis.TypeCheckResult.TypeCheckFailure
 import org.apache.spark.sql.catalyst.analysis.TypeCoercion.numericPrecedence
 import org.apache.spark.sql.catalyst.analysis.TypeCoercionSuite
 import org.apache.spark.sql.catalyst.expressions.aggregate.{CollectList, CollectSet}
@@ -841,12 +842,28 @@ abstract class AnsiCastSuiteBase extends CastSuiteBase {
       cast(Literal(134.12), DecimalType(3, 2)), "cannot be represented")
   }
 
+  protected def setConfigurationHint: String
+
+  private def verifyCastFailure(c: CastBase, optionalExpectedMsg: Option[String] = None): Unit = {
+    val typeCheckResult = c.checkInputDataTypes()
+    assert(typeCheckResult.isFailure)
+    assert(typeCheckResult.isInstanceOf[TypeCheckFailure])
+    val message = typeCheckResult.asInstanceOf[TypeCheckFailure].message
+
+    if (optionalExpectedMsg.isDefined) {
+      assert(message.contains(optionalExpectedMsg.get))
+    } else {
+      assert(message.contains("with ANSI mode on"))
+      assert(message.contains(setConfigurationHint))
+    }
+  }
+
   test("ANSI mode: disallow type conversions between Numeric types and Timestamp type") {
     import DataTypeTestUtils.numericTypes
     checkInvalidCastFromNumericType(TimestampType)
     val timestampLiteral = Literal(1L, TimestampType)
     numericTypes.foreach { numericType =>
-      assert(cast(timestampLiteral, numericType).checkInputDataTypes().isFailure)
+      verifyCastFailure(cast(timestampLiteral, numericType))
     }
   }
 
@@ -855,7 +872,7 @@ abstract class AnsiCastSuiteBase extends CastSuiteBase {
     checkInvalidCastFromNumericType(DateType)
     val dateLiteral = Literal(1, DateType)
     numericTypes.foreach { numericType =>
-      assert(cast(dateLiteral, numericType).checkInputDataTypes().isFailure)
+      verifyCastFailure(cast(dateLiteral, numericType))
     }
   }
 
@@ -880,9 +897,9 @@ abstract class AnsiCastSuiteBase extends CastSuiteBase {
   }
 
   test("ANSI mode: disallow casting complex types as String type") {
-    assert(cast(Literal.create(Array(1, 2, 3, 4, 5)), StringType).checkInputDataTypes().isFailure)
-    assert(cast(Literal.create(Map(1 -> "a")), StringType).checkInputDataTypes().isFailure)
-    assert(cast(Literal.create((1, "a", 0.1)), StringType).checkInputDataTypes().isFailure)
+    verifyCastFailure(cast(Literal.create(Array(1, 2, 3, 4, 5)), StringType))
+    verifyCastFailure(cast(Literal.create(Map(1 -> "a")), StringType))
+    verifyCastFailure(cast(Literal.create((1, "a", 0.1)), StringType))
   }
 
   test("cast from invalid string to numeric should throw NumberFormatException") {
@@ -1489,6 +1506,9 @@ class CastSuiteWithAnsiModeOn extends AnsiCastSuiteBase {
       case _ => Cast(Literal(v), targetType, timeZoneId)
     }
   }
+
+  override def setConfigurationHint: String =
+    s"set ${SQLConf.ANSI_ENABLED.key} as false"
 }
 
 /**
@@ -1511,6 +1531,10 @@ class AnsiCastSuiteWithAnsiModeOn extends AnsiCastSuiteBase {
       case _ => AnsiCast(Literal(v), targetType, timeZoneId)
     }
   }
+
+  override def setConfigurationHint: String =
+    s"set ${SQLConf.STORE_ASSIGNMENT_POLICY.key} as" +
+      s" ${SQLConf.StoreAssignmentPolicy.LEGACY.toString}"
 }
 
 /**
@@ -1533,4 +1557,8 @@ class AnsiCastSuiteWithAnsiModeOff extends AnsiCastSuiteBase {
       case _ => AnsiCast(Literal(v), targetType, timeZoneId)
     }
   }
+
+  override def setConfigurationHint: String =
+    s"set ${SQLConf.STORE_ASSIGNMENT_POLICY.key} as" +
+      s" ${SQLConf.StoreAssignmentPolicy.LEGACY.toString}"
 }