在Apache Beam PCollection中使用AutoValueSchema会产生"RuntimeException:创建者参数arg0与模式字段不对应". [英] Using AutoValueSchema in Apache Beam PCollection gives `RuntimeException: Creator parameter arg0 Doesn't correspond to a schema field`

问题描述

我试图创建一个已创建的由AutoValue定义的对象的PCollection，并且添加了适当的批注，以通过 DefaultSchema(AutoValueSchema.class)来推断Schema.像这样:

I am trying to have a PCollection of AutoValue-defined objects that I have created, and I've added the appropriate annotations to infer the Schema via DefaultSchema(AutoValueSchema.class). Like so:

@DefaultSchema(AutoValueSchema.class)
@AutoValue
public abstract class MyAutoClas {
  public abstract String getMyStr();
  public abstract Integer getMyInt();

  @CreateSchema
  public static MyAutoClass create(String myStr, Integer myInt) {
    return new AutoValue_MyAutoClass(myStr, myInt);
  }
}

我有一个小的测试用例，如下所示:

I have a small test case that looks like this:

PCollection<KV<String, MyAutoClass>> result = pipeline
    .apply(Create.of(MyAutoClass.create("abc", 1)))
    .apply(WithKeys.of(in -> in.getMyStr()));

PAssert.that(result).containsInAnyOrder(KV.of("abc", MyAutoClass.create("abc", 1)));
pipeline.run().waitUntilFinish();

当我尝试运行此代码时，我看到以下错误:

When I try to run this, I am seeing the following errors:

[ERROR] testMyAutoValueClass(.....)  Time elapsed: 1.891 s  <<< ERROR!
java.lang.RuntimeException: Creator parameter arg0 Doesn't correspond to a schema field
    at org.apache.beam.sdk.schemas.utils.ByteBuddyUtils$InvokeUserCreateInstruction.<init>(ByteBuddyUtils.java:717)
    at org.apache.beam.sdk.schemas.utils.ByteBuddyUtils$StaticFactoryMethodInstruction.<init>(ByteBuddyUtils.java:660)
    at org.apache.beam.sdk.schemas.utils.JavaBeanUtils.createStaticCreator(JavaBeanUtils.java:284)
    at org.apache.beam.sdk.schemas.utils.JavaBeanUtils.lambda$getStaticCreator$4(JavaBeanUtils.java:273)
    at java.util.concurrent.ConcurrentHashMap.computeIfAbsent(ConcurrentHashMap.java:1664)
    at org.apache.beam.sdk.schemas.utils.JavaBeanUtils.getStaticCreator(JavaBeanUtils.java:269)
    at org.apache.beam.sdk.schemas.AutoValueSchema.lambda$schemaTypeCreatorFactory$673bce5b$1(AutoValueSchema.java:80)
    at org.apache.beam.sdk.schemas.UserTypeCreatorFactory.create(UserTypeCreatorFactory.java:21)
  ....... [ETCETERA] ......

推荐答案

发生此错误是因为ByteBuddy和Java反射实用程序无法推断您的 @SchemaCreate 方法的参数名称(因此抱怨关于一些未知参数 arg0 -这是默认名称).

This error occurs because ByteBuddy and the Java reflection utilities are not able to infer the parameter names of your @SchemaCreate method (thus complaining about some unknown parameter arg0 - this is the default name).

为确保Java反射可以找到参数名称，您需要指示编译器包括此信息.如果您正在使用Maven进行构建，则可以通过以下方式做到这一点:

To ensure Java reflection can find the parameter names, you need to instruct the compiler to include this information. If you are building with Maven, you can do it this way:

<properties>
    <!-- PLUGIN VERSIONS -->
    <maven-compiler-plugin.version>3.1</maven-compiler-plugin.version>

    <!-- OTHER PROPERTIES -->
    <java.version>1.8</java.version>
</properties>

<build>
    <plugins>
        <plugin>
            <groupId>org.apache.maven.plugins</groupId>
            <artifactId>maven-compiler-plugin</artifactId>
            <version>${maven-compiler-plugin.version}</version>
            <configuration>
                <!-- Original answer -->
                <compilerArgument>-parameters</compilerArgument>
                <!-- Or, if you use the plugin version >= 3.6.2 -->
                <parameters>true</parameters>
                <testCompilerArgument>-parameters</testCompilerArgument>
                <source>${java.version}</source>
                <target>${java.version}</target>
            </configuration>
        </plugin>
    </plugins>
</build>

注意:要使用Gradle完成相同的操作，请使用

Note: To accomplish the same thing with Gradle, use this answer.

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