How to get access to job parameters from ItemReader, in Spring Batch?

Question

This is part of my job.xml:

<job id="foo" job-repository="job-repository">
  <step id="bar">
    <tasklet transaction-manager="transaction-manager">
      <chunk commit-interval="1"
        reader="foo-reader" writer="foo-writer"
      />
    </tasklet>
  </step>
</job>

This is the item reader:

import org.springframework.batch.item.ItemReader;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Component;
@Component("foo-reader")
public final class MyReader implements ItemReader<MyData> {
  @Override
  public MyData read() throws Exception {
    //...
  }
  @Value("#{jobParameters['fileName']}")
  public void setFileName(final String name) {
    //...
  }
}

This is what Spring Batch is saying in runtime:

Field or property 'jobParameters' cannot be found on object of 
type 'org.springframework.beans.factory.config.BeanExpressionContext'

What's wrong here? Where I can read more about these mechanisms in Spring 3.0?

score 83 · Accepted Answer · answered Aug 28 '11 at 03:21

83

As was stated, your reader needs to be 'step' scoped. You can accomplish this via the @Scope("step") annotation. It should work for you if you add that annotation to your reader, like the following:

import org.springframework.batch.item.ItemReader;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Component;

@Component("foo-reader")
@Scope("step")
public final class MyReader implements ItemReader<MyData> {
  @Override
  public MyData read() throws Exception {
    //...
  }

  @Value("#{jobParameters['fileName']}")
  public void setFileName(final String name) {
    //...
  }
}

This scope is not available by default, but will be if you are using the batch XML namespace. If you are not, adding the following to your Spring configuration will make the scope available, per the Spring Batch documentation:

<bean class="org.springframework.batch.core.scope.StepScope" />

answered Aug 28 '11 at 03:21

Sean Kleinjung

3,115
2
21
15

10

`StepScope` is now available by default – Zarathustra Apr 06 '15 at 22:12
1

There's also a shortcut since v2.2 using [@StepScope](http://docs.spring.io/spring-batch/apidocs/org/springframework/batch/core/configuration/annotation/StepScope.html) with @Bean – Guillaume Husta Feb 23 '17 at 09:51
`@Scope("step")` didn't work for me, whereas `@StepScope` did – PixelMaster Aug 08 '18 at 15:40
Spring doesn't really like final classes – gstackoverflow Aug 15 '19 at 20:26
we can annotate the @StepScope on method – Vishal Akkalkote Apr 22 '21 at 12:00

Ortomala Lokni · Answer 2 · 2018-02-25T19:42:53.680

If you want to define your ItemReader instance and your Step instance in a single JavaConfig class. You can use the @StepScope and the @Value annotations such as:

@Configuration
public class ContributionCardBatchConfiguration {

   private static final String WILL_BE_INJECTED = null;

   @Bean
   @StepScope
   public FlatFileItemReader<ContributionCard> contributionCardReader(@Value("#{jobParameters['fileName']}")String contributionCardCsvFileName){

     ....
   }

   @Bean
   Step ingestContributionCardStep(ItemReader<ContributionCard> reader){
         return stepBuilderFactory.get("ingestContributionCardStep")
                 .<ContributionCard, ContributionCard>chunk(1)
                 .reader(contributionCardReader(WILL_BE_INJECTED))
                 .writer(contributionCardWriter())
                 .build();
    }
}

The trick is to pass a null value to the itemReader since it will be injected through the @Value("#{jobParameters['fileName']}") annotation.

Thanks to Tobias Flohre for his article : Spring Batch 2.2 – JavaConfig Part 2: JobParameters, ExecutionContext and StepScope

score 21 · Answer 3 · answered Oct 05 '16 at 12:08

21

Pretty late, but you can also do this by annotating a @BeforeStep method:

@BeforeStep
    public void beforeStep(final StepExecution stepExecution) {
        JobParameters parameters = stepExecution.getJobExecution().getJobParameters();
        //use your parameters
}

answered Oct 05 '16 at 12:08

Alex Pruss

533
5
15

11

This is only useful, if the usage of the job-parameters are *not altering the state* of the ItemReader. If they are e.g. used to designate what data to read, then concurrent execution of the reader might cause incorrect behaviour. – tveon Jan 06 '17 at 14:32
@tveon, this can be solved by using StepScope when declaring the reader bean, right? – Kajzer Sep 07 '18 at 09:22
@Kajzer yes, and unless you reuse the reader later in the same job, then you can also solve it with `JobScope` – tveon Sep 10 '18 at 09:37

score 14 · Answer 4 · answered May 23 '11 at 07:53

14

To be able to use the jobParameters I think you need to define your reader as scope 'step', but I am not sure if you can do it using annotations.

Using xml-config it would go like this:

<bean id="foo-readers" scope="step"
  class="...MyReader">
  <property name="fileName" value="#{jobExecutionContext['fileName']}" />
</bean>

See further at the Spring Batch documentation.

Perhaps it works by using @Scope and defining the step scope in your xml-config:

<bean class="org.springframework.batch.core.scope.StepScope" />

answered May 23 '11 at 07:53

abalogh

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49

I'm interested in annotations specifically. This format of configuration is old and documented. – yegor256 May 23 '11 at 14:48
You haven't stated that you were interested in an annotations-only solution only. Thanks for the vote anyhow. – abalogh May 23 '11 at 15:21

score 5 · Answer 5 · answered Jun 19 '18 at 02:58

5

Complement with an additional example, you can access all job parameters in JavaConfig class:

@Bean
@StepScope
public ItemStreamReader<GenericMessage> reader(@Value("#{jobParameters}") Map<String,Object> jobParameters){
          ....
}

answered Jun 19 '18 at 02:58

dmotta

1,843
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score 2 · Answer 6 · answered Jun 19 '17 at 01:00

While executing the job we need to pass Job parameters as follows:

JobParameters jobParameters= new JobParametersBuilder().addString("file.name", "filename.txt").toJobParameters();   
JobExecution execution = jobLauncher.run(job, jobParameters);

by using the expression language we can import the value as follows:

 #{jobParameters['file.name']}

impactCn · Answer 7 · 2023-06-05T04:00:39.253

'technical' writing.

configuration class.

    @Autowired
    @Qualifier("testReader")
    private testReader reader;


    @Bean(name = "testJob")
    public Job testJob(@Autowired @Qualifier("testStep") Step step) {
        return jobBuilderFactory
                .get("testJob")
                .incrementer(new RunIdIncrementer())
//                .listener(new JobCompletionListener())
                .start(step)
                .build();

    }

    @Bean("testStep")
    @JobScope
    public Step testStep(@Value("#{jobParameters['key']}") String key) {
        return stepBuilderFactory.get("testStep")
                .<UniqueUserVO, List<UniqueUser>>chunk(500)
                .reader(reader.setKey(key).reader())
                .processor(processor.processor())
                .writer(writer.writer())
                .build();

    }

reader interface class.

public interface Reader<T> {

    /**
     * reader 
     * @return
     */
    ItemReader<T> reader();
}

reader class

@Component
public class TestReader implements Reader<UniqueUserVO> {
    private String key;

    public TestReader setKey(String key) {
        this.key= key;
        return this;
    }
    @Override
    public ItemReader<UniqueUserVO> reader() {
       xxxxx
    }
}

Yassine CHABLI · Answer 8 · 2022-06-13T17:32:57.513

-1

This could be an easier manner to do it:

@Configuration
@Setter
@StepScope
public  class Reader extends FlatFileItemReader<Object> {

public Reader(@Value("#{jobParameters['filePath']}") String resource){
    setResource(new FileSystemResource(resource));
   }

}

edited Jun 13 '22 at 17:32

answered Jun 13 '22 at 17:26

Yassine CHABLI

3,459
2
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score -1 · Answer 9 · answered Oct 14 '22 at 08:36

You can use StepExecution context inside a method annotated with @BeforeStep annotation inside your item reader to get the Job parameters & set it to a variable, which you can use inside your read method.

In my case I've written something like this :-

@Component
@RequiredArgsConstructor
public class SpelItemReader implements ItemReader<BatchRequest>{

private String requestId;


@Override
public BatchRequest read() {
   //access the request-id variable here
}

@BeforeStep
public void beforeStep(StepExecution stepExecution) {
    requestId = stepExecution.getJobParameters().getString("requestId");
}

}

score -3 · Answer 10 · edited Dec 17 '13 at 12:50

-3

Did you declare the jobparameters as map properly as bean?

Or did you perhaps accidently instantiate a JobParameters object, which has no getter for the filename?

For more on expression language you can find information in Spring documentation here.

edited Dec 17 '13 at 12:50

emeraldjava

10,894
26
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answered Jun 04 '11 at 09:11

Omnaest

3,096
1
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18

How to get access to job parameters from ItemReader, in Spring Batch?

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