I am using a multiResourceItemReader in spring batch. I found about openCSV that it automatically binds csv columns to java object. But how to replace the FlatFileItemReader/multiResourceItemReader, with openCSV using CsvToBeanBuilder.
The line to object mapping logic in Spring Batch is implemented in a LineMapper, which is used by the FlatFileItemReader to map read lines to domain objects.
So the question "How to replace flatFileItemReader with openCSV in spring batch" is incorrect, those are not at the same level. What you can do is create a LineMapper implementation based on OpenCSV and use it with the FlatFileItemReader.
Related
I am new to Spring Batch and I would like to seek the advice of the experienced programmer on how to implement the following:
I am writing an API that triggers a batch task to generate a report from a list of transactions from JPA repo.
In spring batch, there is ItemReader, ItemProcessor, ItemWriter for each step.
How should I implement my ItemReader such that it can execute the following:
Generate a custom query from the parameters set in the jobParameters (obtained from the API query)
Using the custom query in 2 to obtain the list of transactions from the Transactions JPA repo, which will be processed in the ItemProcessor and subsequently generate reports through ItemWriter.
Question: How should I write the ItemReader, I looking at JpaCursorItemReader (dk if it is the right one) but could not find examples of implementation online to refer to. Any help is appreciated. Thank you.
I am at the stage of trying to understand how Spring batch works, I hope to seek proper guidance from experts in this field of the direction to go to accomplished the mentioned task.
Generate a custom query from the parameters set in the jobParameters (obtained from the API query)
You can define a step-scoped bean and inject job parameters to use them in your query:
#Bean
#StepScope
public JpaCursorItemReader jpaCursorItemReader(#Value("#{jobParameters['parameter']}") String parameter) {
return new JpaCursorItemReaderBuilder()
.queryString("..") // use job parameter in your query here
// set other properties on the item reader
.build();
}
You can find more details on step-scoped components in the documentation here: Late Binding of Job and Step Attributes.
I have the following case and I am trying to solve it with Spring-Boot and Spring-Batch. I have to read a flat file (sidecar file) in which every line is a name of a file to be ingested in a database.
I have configured a job to read the sidecar file, but I am having a problem to decide what is the accepted method in spring-batch to process the contained files. I also have configured steps that can read each file and insert the records in a data base.
Any ideas how to configure the sidecar job with the steps I have written for the individual files.
I can provide actual configuration from my implementation if needed.
FactoryBean is your friend. In this case, you can create a FactoryBean that reads the file of file names and creates a list of Resource objects for it. That can be injected into the MultiResourceItemReader which will iterate over that list.
I am using spring batch for batch processing.
I am using MultiResourceItemReader to initialize the reader object. I did set the resources.
In FlatFileItemReader, i wanted to get the current filename so that i can manipulate data based on filename.
MultiResourceItemReader#getCurrentResource()
This returns the currentResource being read, and Resource has getFileName method which you can use to get the name.
I am new to Spring batch. I wanted to ask how can I write a custom flat file item reader in Spring batch.
I know there is one generic FlatFileItemReader available in Spring batch, but we want to add some business logic while reading then how to write a custom flat file reader.
Thanks in advance
I have done same thing for MultiResourceItemReader, you can extend FlatFileReader and copy complete code of FlatFileReader. Then you can add your own method.
If the in-build logging provided in the FlatFileItemReader is not sufficient for your needs,
Grab the code for the FlatFileItemReader - https://github.com/spring-projects/spring-batch/blob/master/spring-batch-infrastructure/src/main/java/org/springframework/batch/item/file/FlatFileItemReader.java
Rename the class to you class-name/package name
Add loggers as needed and use
I don't recommend this - in more cases you would be better off debugging your code with a debugger.
I'm trying to get a list of job executions which have been stored in Spring batch related tables in the database using:
List<JobExecution> jobExecutions = jobExplorer.getJobExecutions(jobInstance);
The above method call seems to invoke ExecutionContextRowMapper.mapRow method in JdbcExecutionContextDao class.
The ExecutionContextRowMapper uses com.thoughtworks.xstream.Xstream.fromXML method to deserialize the JSON string of JobExecutionContext stored in DB.
It looks like an incorrect or default xml deserializer is used for unmarshalling JSONified JobExecutionContext.
Is there any configuration to use a JSON deserializer in this scenario.
The serializer/deserializer for the ExecutionContext is configurable in 2.2.x. We use the ExecutionContextSerializer interface (providing two implementations, one using java serialization and one using the XStream impl you mention). To configure your own serializer, you'll need to implement the org.springframework.batch.core.repository.ExecutionContextSerializer and inject it into the JobRepositoryFactoryBean (so that the contexts are serialized/deserialized correctly) and the JobExplorerFactoryBean (to reserialize the previously saved contexts).
It is important to note that changing the serialization method will prevent Spring Batch from deserializing previously saved ExecutionContexts.