Spring boot CLI client with Rest Api

Question

I try to build a CLI client in maven by using spring boot to consume my rest api but I have difficulties to consume it.

When I send a request they print something about jackson (see below)

I don't understand the message error at all.

here is the main class:

@SpringBootApplication(exclude = {DataSourceAutoConfiguration.class })
public class RestClientApplication implements ApplicationRunner {
    @Autowired
    private PrisonerResource prisonerResource;

    public static void main(String[] args) {
        SpringApplication.run(RestClientApplication.class, args);
    }


    @Override
    public void run(ApplicationArguments args) throws Exception {
        if (args.containsOption("app.action")) {
            switch (args.getOptionValues("app.action").get(0)){
                case "readOnePrisoner":
                    try {
                        PrisonerEntity prisonerDto = prisonerResource.readOne(args.getOptionValues("app.firstName").get(0));
                        System.out.println(prisonerDto.getFirstName());
                    } catch (HttpClientErrorException e) {
                        if (e.getStatusCode()== HttpStatus.NOT_FOUND)
                            System.err.println("not found");
                    }
                    break;
                case "readAllPrisoner":
                    break;
                case "deletePrisoner":
                    try{
                        prisonerResource.delete(args.getOptionValues("app.firstName").get(0));

                    } catch (HttpClientErrorException e){
                        if (e.getStatusCode()== HttpStatus.NOT_FOUND);
                        System.err.println("not found");
                    }
                    break;
                case "updatePrisoner":
                    try{
                        prisonerResource.update(args.getOptionValues("app.firstName").get(0));

                    } catch(HttpClientErrorException e){

                    }
                    break;
                case "createPrisoner":
                    try{
                        prisonerResource.create();

                    } catch(HttpClientErrorException e){

                    }
                    break;

here is the PrisonerResource class :

@Component
public class PrisonerResource {
    private final RestTemplate restTemplate;

    @Autowired
    public PrisonerResource(RestTemplateBuilder restTemplateBuilder) {
        this.restTemplate = restTemplateBuilder.rootUri("http//localhost/api/v1/prisoners").build();
    }


    private PrisonerEntity prisoner;

    public void create(){
        PrisonerEntity response = restTemplate.postForObject("",prisoner,PrisonerEntity.class);
        return;
    }


    public PrisonerEntity readOne(String id){
        return restTemplate.getForObject("/{id}", PrisonerEntity.class, id);
    }

    public PagedModel<PrisonerEntity> readAll(int page) {
        ResponseEntity<PagedModel<PrisonerEntity>> result = restTemplate.exchange("/?page={page}",
                HttpMethod.GET,
                null, new ParameterizedTypeReference<PagedModel<PrisonerEntity>>() {},
                page);
        return result.getBody();
    }

    public void update(String id){
        restTemplate.put("/{id}", PrisonerEntity.class, id);
        return ;

    }

    public void delete(String id){
        restTemplate.delete("/{id}", PrisonerEntity.class, id);
        return ;
    }
}

I use the client with this command :

java -jar target/rest_client-0.0.1-SNAPSHOT.jar --app.action=readOnePrisoner --app.firstName=Alan

and I got this error:

Error starting ApplicationContext. To display the conditions report re-run your application with 'debug' enabled.
]
        at com.fasterxml.jackson.databind.deser.BeanDeserializer.deserialize(BeanDeserializer.java:164) ~[jackson-databind-2.11.4.jar!/:2.11.4]
        at com.fasterxml.jackson.databind.deser.std.CollectionDeserializer.deserialize(CollectionDeserializer.java:290) ~[jackson-databind-2.11.4.jar!/:
2.11.4]
        at com.fasterxml.jackson.databind.deser.std.CollectionDeserializer.deserialize(CollectionDeserializer.java:249) ~[jackson-databind-2.11.4.jar!/:
2.11.4]
        at com.fasterxml.jackson.databind.deser.std.CollectionDeserializer.deserialize(CollectionDeserializer.java:26) ~[jackson-databind-2.11.4.jar!/:2
.11.4]
        at com.fasterxml.jackson.databind.deser.impl.MethodProperty.deserializeAndSet(MethodProperty.java:129) ~[jackson-databind-2.11.4.jar!/:2.11.4]
        at com.fasterxml.jackson.databind.deser.BeanDeserializer.deserializeFromObject(BeanDeserializer.java:371) ~[jackson-databind-2.11.4.jar!/:2.11.4
]
        at com.fasterxml.jackson.databind.deser.BeanDeserializer.deserialize(BeanDeserializer.java:164) ~[jackson-databind-2.11.4.jar!/:2.11.4]
        at com.fasterxml.jackson.databind.deser.impl.MethodProperty.deserializeAndSet(MethodProperty.java:129) ~[jackson-databind-2.11.4.jar!/:2.11.4]
        at com.fasterxml.jackson.databind.deser.BeanDeserializer.deserializeFromObject(BeanDeserializer.java:371) ~[jackson-databind-2.11.4.jar!/:2.11.4
]
        at com.fasterxml.jackson.databind.deser.BeanDeserializer.deserialize(BeanDeserializer.java:164) ~[jackson-databind-2.11.4.jar!/:2.11.4]

Answer 1

Looks like an attempt to deserialise some json is failing...

This line from you main application:

prisonerResource.readOne(args.getOptionValues("app.firstName").get(0))

...calls:

public PrisonerEntity readOne(String id){
        return restTemplate.getForObject("/{id}", PrisonerEntity.class, id);
    }

It seems likely the call to get the PrisonerEntity is returning {} or nothing at all.

If you can put a breakpoint on these two lines and run them through the expression evaluator in IntelliJ Idea (Alt + F8, usually)...

Theres also often an autowired deserialisation class for the PrisonerEntity somewhere .. likely named something like PrisonerEntityDeserialiser (or similar) you may be able to set a break point in there and evaluate what's being returned before jackson attempts to convert it from a json (String) to an object, so you may be able to debug the issue better there.