Type of TypeVariable 'OT' in 'class org.apache.flink.api.common.io.RichInputFormat' could not be determined.

[Robertson Williams]

I test streaming to read data through JDBCInputFormat with code snippet as below (scala 2.11, flink 1.0)

val input = JDBCInputFormat.buildJDBCInputFormat.

                    setDrivername(driver).

                    setDBUrl(url).

                    setQuery(sql).

                    setUsername(user).

                    setPassword(password).

                    finish.

                    asInstanceOf[JDBCInputFormat[Tuple1[String]]]

val env = StreamExecutionEnvironment.getExecutionEnvironment  

    val dataset = env.createInput(input)

    dataset.writeAsText("/tmp/jdbc.txt")

    env.execute("jdbc-test")

However submitting the job it throws 

Type of TypeVariable 'OT' in 'class org.apache.flink.api.common.io.RichInputFormat' could not be determined. This is most likely a type erasure problem. The type extraction currently supports types with generic variables only in cases where all variables in the return type can be deduced from the input type(s).

org.apache.flink.api.java.typeutils.TypeExtractor.createTypeInfoWithTypeHierarchy(TypeExtractor.java:670)

org.apache.flink.api.java.typeutils.TypeExtractor.privateCreateTypeInfo(TypeExtractor.java:564)

org.apache.flink.api.java.typeutils.TypeExtractor.getInputFormatTypes(TypeExtractor.java:272)

org.apache.flink.streaming.api.environment.StreamExecutionEnvironment.createInput(StreamExecutionEnvironment.java:1011)

org.apache.flink.streaming.api.scala.StreamExecutionEnvironment.createInput(StreamExecutionEnvironment.scala:484)

Where should I add that OT stuff so to avoid the type erasure problem?

Thanks

[Maximilian Michels]

Hi Robertson,

You need to supply a TypeInformation for the data read from the InputFormat.

val dataset = env.createInput(input, new TupleTypeInfo(Tuple1.class,
BasicTypeInfo.STRING_TYPE_INFO))

should do the trick.

Cheers,
Max

On Tue, May 31, 2016 at 1:13 PM, Robertson Williams
<[hidden email]> wrote:

> I test streaming to read data through JDBCInputFormat with code snippet as
> below (scala 2.11, flink 1.0)
>
> val input = JDBCInputFormat.buildJDBCInputFormat.
>                     setDrivername(driver).
>                     setDBUrl(url).
>                     setQuery(sql).
>                     setUsername(user).
>                     setPassword(password).
>                     finish.
>                     asInstanceOf[JDBCInputFormat[Tuple1[String]]]
>
>
> val env = StreamExecutionEnvironment.getExecutionEnvironment
>     val dataset = env.createInput(input)
>     dataset.writeAsText("/tmp/jdbc.txt")
>     env.execute("jdbc-test")
>
> However submitting the job it throws
>
> Type of TypeVariable 'OT' in 'class
> org.apache.flink.api.common.io.RichInputFormat' could not be determined.
> This is most likely a type erasure problem. The type extraction currently
> supports types with generic variables only in cases where all variables in
> the return type can be deduced from the input type(s).
> org.apache.flink.api.java.typeutils.TypeExtractor.createTypeInfoWithTypeHierarchy(TypeExtractor.java:670)
> org.apache.flink.api.java.typeutils.TypeExtractor.privateCreateTypeInfo(TypeExtractor.java:564)
> org.apache.flink.api.java.typeutils.TypeExtractor.getInputFormatTypes(TypeExtractor.java:272)
> org.apache.flink.streaming.api.environment.StreamExecutionEnvironment.createInput(StreamExecutionEnvironment.java:1011)
> org.apache.flink.streaming.api.scala.StreamExecutionEnvironment.createInput(StreamExecutionEnvironment.scala:484)
>
> Where should I add that OT stuff so to avoid the type erasure problem?
>
> Thanks
>
>