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https://issues.apache.org/jira/browse/FLINK-2557?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14708505#comment-14708505
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ASF GitHub Bot commented on FLINK-2557:
---------------------------------------
GitHub user zentol opened a pull request:
https://github.com/apache/flink/pull/1045
[FLINK-2557] TypeExtractor properly returns MissingTypeInfo
This fix is not really obvious so let me explain:
getParameterTye() is called from two different places in the TypeExtractor;
to validate the input type and to extract the output type.
Both cases consider the possibility that getParameterType() fails, but
check for different exceptions.
The TypeExtractor only returns a MissingTypeInfo if it encounters an
InvalidTypesException; IllegalArgumentExceptions are not catched. This is what
@mjsax encountered.
Changing the exception type causes the TypeExtractor to properly return a
MissingTypeInfo, which is later overridden by the returns(...) call.
In order for the input validation to still work properly aswell, it now
catches InvalidTypesExceptions instead.
You can merge this pull request into a Git repository by running:
$ git pull https://github.com/zentol/flink 2557_types
Alternatively you can review and apply these changes as the patch at:
https://github.com/apache/flink/pull/1045.patch
To close this pull request, make a commit to your master/trunk branch
with (at least) the following in the commit message:
This closes #1045
----
commit 1c1dc459915c875ab0a4412aa3ef0a844f092171
Author: zentol <[email protected]>
Date: 2015-08-23T19:41:44Z
[FLINK-2557] TypeExtractor properly returns MissingTypeInfo
----
> Manual type information via "returns" fails in DataSet API
> ----------------------------------------------------------
>
> Key: FLINK-2557
> URL: https://issues.apache.org/jira/browse/FLINK-2557
> Project: Flink
> Issue Type: Bug
> Components: Java API
> Reporter: Matthias J. Sax
> Assignee: Chesnay Schepler
>
> I changed the WordCount example as below and get an exception:
> Tokenizer is change to this (removed generics and added cast to String):
> {code:java}
> public static final class Tokenizer implements FlatMapFunction {
> public void flatMap(Object value, Collector out) {
> String[] tokens = ((String) value).toLowerCase().split("\\W+");
> for (String token : tokens) {
> if (token.length() > 0) {
> out.collect(new Tuple2<String, Integer>(token,
> 1));
> }
> }
> }
> }
> {code}
> I added call to "returns(....)" here:
> {code:java}
> DataSet<Tuple2<String, Integer>> counts =
> text.flatMap(new Tokenizer()).returns("Tuple2<String,Integer>")
> .groupBy(0).sum(1);
> {code}
> The exception is:
> {noformat}
> Exception in thread "main" java.lang.IllegalArgumentException: The types of
> the interface org.apache.flink.api.common.functions.FlatMapFunction could not
> be inferred. Support for synthetic interfaces, lambdas, and generic types is
> limited at this point.
> at
> org.apache.flink.api.java.typeutils.TypeExtractor.getParameterType(TypeExtractor.java:686)
> at
> org.apache.flink.api.java.typeutils.TypeExtractor.getParameterTypeFromGenericType(TypeExtractor.java:710)
> at
> org.apache.flink.api.java.typeutils.TypeExtractor.getParameterType(TypeExtractor.java:673)
> at
> org.apache.flink.api.java.typeutils.TypeExtractor.privateCreateTypeInfo(TypeExtractor.java:365)
> at
> org.apache.flink.api.java.typeutils.TypeExtractor.getUnaryOperatorReturnType(TypeExtractor.java:279)
> at
> org.apache.flink.api.java.typeutils.TypeExtractor.getFlatMapReturnTypes(TypeExtractor.java:120)
> at org.apache.flink.api.java.DataSet.flatMap(DataSet.java:262)
> at
> org.apache.flink.examples.java.wordcount.WordCount.main(WordCount.java:69)
> {noformat}
> Fix:
> This should not immediately fail, but also only give a "MissingTypeInfo" so
> that type hints would work.
> The error message is also wrong, btw: It should state that raw types are not
> supported.
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