Spring Mongo Populator one by one - spring

Question

I'm using MongoDB and Spring over Kotlin and i want my application to populate a MongoDB collection upon startup. (and clean it every time it starts)
My question is, how can i populate the data one by one in order to be fault tolerant in case some of the data I'm populating with is problematic?
my code:
#Configuration
class IndicatorPopulator {
#Value("classpath:indicatorData.json")
private lateinit var data: Resource
#Autowired
private lateinit var indicatorRepository: IndicatorRepository
#Bean
#Autowired
fun repositoryPopulator(objectMapper: ObjectMapper): Jackson2RepositoryPopulatorFactoryBean {
val factory = Jackson2RepositoryPopulatorFactoryBean()
indicatorRepository.deleteAll()
factory.setMapper(objectMapper)
factory.setResources(arrayOf(data))
return factory
}
What I am looking for is something like:
#Bean
#Autowired
fun repositoryPopulator(objectMapper: ObjectMapper): Jackson2RepositoryPopulatorFactoryBean {
val factory = Jackson2RepositoryPopulatorFactoryBean()
indicatorRepository.deleteAll()
factory.setMapper(objectMapper)
val arrayOfResources: Array<Resource> = arrayOf(data)
for (resource in arrayOfResources){
try{
factory.setResources(resource)
} catch(e: Exception){
logger.log(e.message)
}
}
return factory
}
Any idea on how to do something like that would be helpful...
Thanks in advance.

Answer 1

There is no built in support for your ask but you can easily provide by tweaking few classes.
Add Custom Jackson 2 Reader
public class CustomJackson2ResourceReader implements ResourceReader {
private static final Logger logger = LoggerFactory.getLogger(CustomJackson2ResourceReader.class);
private final Jackson2ResourceReader resourceReader = new Jackson2ResourceReader();
#Override
public Object readFrom(Resource resource, ClassLoader classLoader) throws Exception {
Object result;
try {
result = resourceReader.readFrom(resource, classLoader);
} catch(Exception e) {
logger.warn("Can't read from resource", e);
return Collections.EMPTY_LIST;
}
return result;
}
}
Add Custom Jackson 2 Populator
public class CustomJackson2RepositoryPopulatorFactoryBean extends Jackson2RepositoryPopulatorFactoryBean {
#Override
protected ResourceReader getResourceReader() {
return new CustomJackson2ResourceReader();
}
}
Configuration
#SpringBootApplication
public class DemoApplication {
public static void main(String[] args) {
SpringApplication.run(DemoApplication.class, args);
}
#Bean
public AbstractRepositoryPopulatorFactoryBean repositoryPopulator(ObjectMapper objectMapper, KeyValueRepository keyValueRepository) {
Jackson2RepositoryPopulatorFactoryBean factory = new CustomJackson2RepositoryPopulatorFactoryBean();
keyValueRepository.deleteAll();
factory.setMapper(objectMapper);
factory.setResources(new Resource[]{new ClassPathResource("badclassname.json"), new ClassPathResource("good.json"), new ClassPathResource("malformatted.json")});
return factory;
}
}
I've uploading a working example here

Answer 2

Using Sagar's Reader & Factory I just adjusted it to fit my needs (Kotlin, and reading resources all from the same JSON file) got me this answer:
#Configuration
class IndicatorPopulator {
#Value("classpath:indicatorData.json")
private lateinit var data: Resource
#Autowired
private lateinit var indicatorRepository: IndicatorRepository
#Autowired
#Bean
fun repositoryPopulator(objectMapper: ObjectMapper): Jackson2RepositoryPopulatorFactoryBean {
val factory: Jackson2RepositoryPopulatorFactoryBean = CustomJackson2RepositoryPopulatorFactoryBean()
factory.setMapper(objectMapper)
// inject your Jackson Object Mapper if you need to customize it:
indicatorRepository.deleteAll()
val resources = mutableListOf<Resource>()
val readTree: ArrayNode = objectMapper.readTree(data.inputStream) as ArrayNode
for (node in readTree){
resources.add( InputStreamResource(node.toString().byteInputStream()))
}
factory.setResources(resources.toTypedArray())
return factory
}
}