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From: fhueske <git@git.apache.org>
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Subject: [GitHub] flink pull request #2653: [FLINK-4469] [table] Add support for user defined ...
Content-Type: text/plain
Message-Id: <20161116224935.55DEAF1785@git1-us-west.apache.org>
Date: Wed, 16 Nov 2016 22:49:35 +0000 (UTC)
archived-at: Wed, 16 Nov 2016 22:50:55 -0000

Github user fhueske commented on a diff in the pull request:

    https://github.com/apache/flink/pull/2653#discussion_r88346802
  
    --- Diff: flink-libraries/flink-table/src/main/scala/org/apache/flink/api/table/validate/FunctionCatalog.scala ---
    @@ -47,13 +52,50 @@ class FunctionCatalog {
         sqlFunctions += sqlFunction
       }
     
    +  /** Register multiple sql functions at one time. The functions has the same name. **/
    +  def registerSqlFunctions(functions: Seq[SqlFunction]): Unit = {
    +    if (functions.nonEmpty) {
    +      sqlFunctions --= sqlFunctions.filter(_.getName == functions.head.getName)
    +      sqlFunctions ++= functions
    +    }
    +  }
    +
       def getSqlOperatorTable: SqlOperatorTable =
         ChainedSqlOperatorTable.of(
           new BasicOperatorTable(),
           new ListSqlOperatorTable(sqlFunctions)
         )
     
       /**
    +    * Lookup table function and create an TableFunctionCall if we find a match.
    +    */
    +  def lookupTableFunction[T](name: String, children: Seq[Expression]): TableFunctionCall[T] = {
    +    val funcClass = functionBuilders
    +      .getOrElse(name.toLowerCase, throw ValidationException(s"Undefined function: $name"))
    +    funcClass match {
    +      // user-defined table function call
    +      case tf if classOf[TableFunction[T]].isAssignableFrom(tf) =>
    +        Try(UserDefinedFunctionUtils.instantiate(tf.asInstanceOf[Class[TableFunction[T]]])) match {
    +          case Success(tableFunction) => {
    +            val clazz: Type = tableFunction.getClass.getGenericSuperclass
    +            val generic = clazz match {
    +              case cls: ParameterizedType => cls.getActualTypeArguments.toSeq.head
    +              case _ => throw new TableException(
    +                "New TableFunction classes need to inherit from TableFunction class," +
    +                  " and statement the generic type.")
    +            }
    +            implicit val typeInfo: TypeInformation[T] = TypeExtractor.createTypeInfo(generic)
    +              .asInstanceOf[TypeInformation[T]]
    +            TableFunctionCall(tableFunction, children, None)
    +          }
    +          case Failure(e) => throw ValidationException(e.getMessage)
    +        }
    +      case _ =>
    +        throw ValidationException("Unsupported table function.")
    --- End diff --
    
    I think this exception message could be improved. It is throw if the registered method does not implement the `TableFunction` interface.


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