Flink嵌套类到DataStream转换错误

roqulrg3  于 2023-08-01  发布在  Apache
关注(0)|答案(2)|浏览(195)

我用的是Flink 1.13我试图以下面的方式将表结果转换为数据流,但不断出错。

public class HybridTrial {
  public static class Address {
    public String street;
    public String houseNumber;

    public Address() {}

    public Address(String street, String houseNumber) {
      this.street = street;
      this.houseNumber = houseNumber;
    }
  }

  public static class User {
    public String name;

    public Integer score;

    public LocalDateTime event_time;

    public Address address;

    // default constructor for DataStream API
    public User() {}

    // fully assigning constructor for Table API
    public User(String name, Integer score, LocalDateTime event_time, Address address) {
      this.name = name;
      this.score = score;
      this.event_time = event_time;
      this.address = address;
    }
  }

  public static void main(String[] args) throws Exception {
    StreamExecutionEnvironment env = StreamExecutionEnvironment.getExecutionEnvironment();
    DataStream<User> dataStream =
        env.fromElements(
                new User("Alice", 4, LocalDateTime.now(), new Address()),
                new User("Bob", 6, LocalDateTime.now(), new Address("NBC", "204")),
                new User("Alice", 10, LocalDateTime.now(), new Address("ABC", "1033")))
            .assignTimestampsAndWatermarks(
                WatermarkStrategy.<User>forBoundedOutOfOrderness(Duration.ofSeconds(60)));

    StreamTableEnvironment tableEnv = StreamTableEnvironment.create(env);
    Table table =
        tableEnv.fromDataStream(
            dataStream, Schema.newBuilder().build());

    table.printSchema();

    Table t = table.select($("*"));

    DataStream<User> dsRow = tableEnv.toDataStream(t,User.class);
    dsRow.print();

    env.execute();
  }
}

字符串
我得到的错误是:

Exception in thread "main" org.apache.flink.table.api.ValidationException: Column types of query result and sink for registered table 'default_catalog.default_database.Unregistered_DataStream_Sink_1' do not match.
Cause: Incompatible types for sink column 'event_time' at position 2.

Query schema: [name: STRING, score: INT, event_time: RAW('java.time.LocalDateTime', '...'), address: *flinkSqlExperiments.HybridTrial$Address<`street` STRING, `houseNumber` STRING>*]
Sink schema:  [name: STRING, score: INT, event_time: TIMESTAMP(9), address: *flinkSqlExperiments.HybridTrial$Address<`street` STRING, `houseNumber` STRING>*]
    at org.apache.flink.table.planner.connectors.DynamicSinkUtils.createSchemaMismatchException(DynamicSinkUtils.java:437)
    at org.apache.flink.table.planner.connectors.DynamicSinkUtils.validateSchemaAndApplyImplicitCast(DynamicSinkUtils.java:256)
    at org.apache.flink.table.planner.connectors.DynamicSinkUtils.convertSinkToRel(DynamicSinkUtils.java:198)
    at org.apache.flink.table.planner.connectors.DynamicSinkUtils.convertExternalToRel(DynamicSinkUtils.java:143)


我也尝试了从DataStream到表的自定义转换,但从表到DataStream的转换仍然出错。我被困住了,所以任何帮助都很感激。

6yjfywim

6yjfywim1#

DataStream中自动的、基于反射的类型提取不如API中的类型提取功能强大。这也是由于DataStream API中的状态向后兼容性问题。
event_time字段是DataStream API中的GenericType,其导致Table API中的RAW。您有以下可能性:

  • fromElements中给予适当的TypeInformation
  • 使用fromDataStream中的DataType覆盖TypeInformation
iovurdzv

iovurdzv2#

它通过使用下面的方法注册POJO解决了我的问题
env.getConfig().registerPojoType(YourClass.class);
您可以使用任何用户定义的DTO并注册为POJO

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