I have to call a microservice from a batch launched from another microservice using spring-batch and openfeign - spring

Question

I don't know if it's possible, but this is my question:
I hava a batch developed using spring-boot and spring-batch, and I have to call another microservice using Feign...
...help!
this is my class Reader
package it.batch.step;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.batch.item.ItemReader;
import org.springframework.batch.item.NonTransientResourceException;
import org.springframework.batch.item.ParseException;
import org.springframework.batch.item.UnexpectedInputException;
import org.springframework.beans.factory.annotation.Autowired;
import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.ObjectMapper;
import it.client.feign.EmailAccountClient;
import it.dto.feign.mail.account.AccountOutDto;
import it.dto.feign.mail.account.SearchAccountFilterDto;
import it.dto.feign.mail.account.SearchAccountResponseDto;
public class Reader implements ItemReader <String> {
private static final Logger LOGGER = LoggerFactory.getLogger(Reader.class);
private int count = 0;
#Autowired
private EmailAccountClient emailAccountClient;
#Override
public String read() throws Exception, UnexpectedInputException, ParseException, NonTransientResourceException {
LOGGER.info("read - begin ");
SearchAccountResponseDto clientResponse = emailAccountClient.searchAccount(getFilter());
if (count < clientResponse.getAccounts().size()) {
return convertToJsonString(clientResponse.getAccounts().get(count++));
} else {
count = 0;
}
return null;
}
private static SearchAccountFilterDto getFilter() {
SearchAccountFilterDto filter = new SearchAccountFilterDto();
return filter;
}
private String convertToJsonString(AccountOutDto account) {
ObjectMapper mapper = new ObjectMapper();
String jsonString = "";
try {
jsonString = mapper.writeValueAsString(account);
} catch (JsonProcessingException e) {
e.printStackTrace();
}
LOGGER.info("Contenuto JSON: " + jsonString);
return jsonString;
}
}
...
when I launch the batch I have this error:
java.lang.NullPointerException: null
at it.batch.step.Reader.read(Reader.java:32) ~[classes/:?]
where line 32 is:
SearchAccountResponseDto clientResponse = emailAccountClient.searchAccount(getFilter());
EmailAccountClient is null

Answer 1

Your client is null: your reader is not a #Component so Spring can't autowire the client. You must use a workaround like passing the autowired client through the constructor when you instantiate the reader, like this:
private EmailAccountClient client;
public reader(EmailAccountClient client){
this.client=client;
}
in the other class:
#Autowired
private EmailAccountClient client;
#Bean
public ItemReader<String> reader(){
return new Reader(client)
}