How to pass JobParameters to myBatisPagingItemReader without using #StepScope - spring-batch

Question

I am using spring batch restart functionality so that it reads from the last failed point forward. My restart works fine as long as I don't use #StepScope annotation to my myBatisPagingItemReader bean method.
I have to use #StepScope so that i can do late binding to get the jobParameters using the input parameter to my myBatisPagingItemReader bean method
#Value("#{JobParameters['run-date']}"))
If I use #StepScope the restart does not work.
I tried adding listener new JobParameterExecutionContextCopyListener() to copy JobParameters to ExecutionContext.
But how will i get access to ExecutionContext inside myBatisPagingItemReader as I don't have ItemReader's open methods?
Not sure how i can get access to jobParameters when running myBatisPagingItemReader without using #StepScope? Please any inputs.
Also not sure if my understanding on spring-batch restart is correct on how it works when new instance (stateful) is used when using #StepScope.
#Configuration
#EnableBatchProcessing
public class BatchConfig {
#Bean
public Step step1(StepBuilderFactory stepBuilderFactory,
ItemReader<Model> myBatisPagingItemReader,
ItemProcessor<Model, Model> itemProcessor,
ItemWriter<Model> itemWriter) {
return stepBuilderFactory.get("data-load")
.<Model, Model>chunk(10)
.reader(myBatisPagingItemReader)
.processor(itemProcessor)
.writer(itemWriter)
.listener(itemReadListener())
.listener(new JobParameterExecutionContextCopyListener())
.build();
}
#Bean
public Job job(JobBuilderFactory jobBuilderFactory, #Qualifier("step1")
Step step1) {
return jobBuilderFactory.get("load-job")
.incrementer(new RunIdIncrementer())
.start(step1)
.listener(jobExecutionListener())
.build();
}
}
#Component
public class BatchInputReader {
#Bean
//#StepScope
public ItemReader<Model> myBatisPagingItemReader(
SqlSessionFactory sqlSessionFactory) {
MyBatisPagingItemReader<Model> reader = new
MyBatisPagingItemReader<>();
Map<String, Object> parameterValues = new HashMap<>();
// populate parameterValues from jobParameters ??
reader.setSqlSessionFactory(sqlSessionFactory);
reader.setParameterValues(parameterValues);
reader.setQueryId("query");
return reader;
}
}

Answer 1

You are declaring a Spring Bean (myBatisPagingItemReader) in a Class annotated with #Component (BatchInputReader). This is not correct.
What you need to do is to declare the mybatis reader as a bean in your configuration class BatchConfig. Once this is done and the bean is annotated with #StepScope, you can pass pass job parameters as follows:
#Configuration
#EnableBatchProcessing
public class BatchConfig {
#Bean
#StepScope
public ItemReader<Model> myBatisPagingItemReader(
SqlSessionFactory sqlSessionFactory,
#Value("#{jobParameters['param1']}") String param1,
#Value("#{jobParameters['param2']}") String param2) {
MyBatisPagingItemReader<Model> reader = new
MyBatisPagingItemReader<>();
Map<String, Object> parameterValues = new HashMap<>();
// populate parameterValues from jobParameters ?? => Those can be now accessed from method parameters
reader.setSqlSessionFactory(sqlSessionFactory);
reader.setParameterValues(parameterValues);
reader.setQueryId("query");
return reader;
}
#Bean
public Step step1(StepBuilderFactory stepBuilderFactory,
ItemReader<Model> myBatisPagingItemReader,
ItemProcessor<Model, Model> itemProcessor,
ItemWriter<Model> itemWriter) {
return stepBuilderFactory.get("data-load")
.<Model, Model>chunk(10)
.reader(myBatisPagingItemReader)
.processor(itemProcessor)
.writer(itemWriter)
.listener(itemReadListener())
.listener(new JobParameterExecutionContextCopyListener())
.build();
}
#Bean
public Job job(JobBuilderFactory jobBuilderFactory, #Qualifier("step1")
Step step1) {
return jobBuilderFactory.get("load-job")
.incrementer(new RunIdIncrementer())
.start(step1)
.listener(jobExecutionListener())
.build();
}
}
More details about this in the Late Binding of Job and Step Attributes section. BatchInputReader will be left empty and is not needed anymore. Less is more! :-)
Hope this helps.

Answer 2

Adding to my question. I have added myBatisPagingItemReader() as suggested to my configuration annoated class.
Restart example when I use #Stepscope annotaton to myBatisPagingItemReader(), the reader is fetching 5 records and I have chunk size(commit-interval) set to 3.
Job Instance - 01 - Job Parameter - 01/02/2019.
chunk-1:
- process record-1
- process record-2
- process record-3
writer - writes all 3 records
chunk-1 commit successful
chunk-2:
process record-4
process record-5 - Throws and exception
Job completes and set to 'FAILED' status
Now the Job is Restarted again using same Job Parameter.
Job Instance - 01 - Job Parameter - 01/02/2019.
chunk-1:
process record-1
process record-2
process record-3
writer - writes all 3 records
chunk-1 commit successful
chunk-2:
process record-4
process record-5 - Throws and exception
Job completes and set to 'FAILED' status
Please note: Here as I am using #Stepscope annotation on myBatisPagingItemReader() bean method, the job creates a new instance , see below log message.
Creating object in scope=step, name=scopedTarget.myBatisPagingItemReader
Registered destruction callback in scope=step, name=scopedTarget.myBatisPagingItemReader
As it is new instance it start the process from start, instead of starting from chunk-2.
If i don't use Stepscope, it restarts from chunk-2 as the restarted job step sets - MyBatisPagingItemReader.read.count=3.
I would like to use Stepscope to use the late bindings, if i use stepscope, is it possible for my myBatisPagingItemReader to set the read.count from the last failure to get restart working?
Or
If I don't use #Stepscope, is there a way to get job parameters inside myBatisPagingItemReader?