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https://issues.apache.org/jira/browse/FLINK-9742?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Fabian Hueske closed FLINK-9742.
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Resolution: Fixed
> Expose Expression.resultType to public
> --------------------------------------
>
> Key: FLINK-9742
> URL: https://issues.apache.org/jira/browse/FLINK-9742
> Project: Flink
> Issue Type: Improvement
> Components: Table API & SQL
> Affects Versions: 1.5.0
> Reporter: Jungtaek Lim
> Priority: Major
> Labels: pull-request-available
>
> I have use case of TableSource which requires custom implementation of
> TimestampExtractor. To ensure new TimestampExtractor to cover more general
> use cases, accessing Expression.resultType is necessary, but its scope is now
> defined as package private for "org.apache.flink".
> Below is the implementation of custom TimestampExtractor which leverages
> Expression.resultType, hence had to place it to org.apache.flink package
> (looks like a hack).
> {code:java}
> class IsoDateStringAwareExistingField(val field: String) extends
> TimestampExtractor {
> override def getArgumentFields: Array[String] = Array(field)
> override def validateArgumentFields(argumentFieldTypes:
> Array[TypeInformation[_]]): Unit = {
> val fieldType = argumentFieldTypes(0)
> fieldType match {
> case Types.LONG => // OK
> case Types.SQL_TIMESTAMP => // OK
> case Types.STRING => // OK
> case _: TypeInformation[_] =>
> throw ValidationException(
> s"Field '$field' must be of type Long or Timestamp or String but is
> of type $fieldType.")
> }
> }
> override def getExpression(fieldAccesses: Array[ResolvedFieldReference]):
> Expression = {
> val fieldAccess: Expression = fieldAccesses(0)
> fieldAccess.resultType match {
> case Types.LONG =>
> // access LONG field
> fieldAccess
> case Types.SQL_TIMESTAMP =>
> // cast timestamp to long
> Cast(fieldAccess, Types.LONG)
> case Types.STRING =>
> Cast(Cast(fieldAccess, SqlTimeTypeInfo.TIMESTAMP), Types.LONG)
> }
> }
> }{code}
> It would be better to just make Expression.resultType public to cover other
> cases as well. (I'm not sure other methods would be also better to be public
> as well.)
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