如何使用springboot创建mongodb通用rest api？

Question

I'm creating an application to display different intresting data. I've been trying create generics REST controllers for several days. I need generic mongodb repository, which is used in generic service, which is used in generic controller:) You can see that schema on picture.

Value.java

    @Data
    @NoArgsConstructor
    public class Value implements Serializable {

    @Id
    String id;
    String description;
    Integer value;

    public Value(int value, String description) {
        this.description = description;
        this.value = value;
     }
}

SpeedValue.java

@Data
@EqualsAndHashCode(callSuper = true)

@Document(collection = "speed_values")
public class SpeedValue extends Value {

    public SpeedValue(int value, String description) {
        super(value, description);
    }

}

CurrencyValue.java

@EqualsAndHashCode(callSuper = true)
@Data

@Document(collection = "currency_values")
public class CurrencyValue extends Value {

    public CurrencyValue(int value, String description) {
        super(value, description);
    }
}

My generic repository:

@NoRepositoryBean
public interface GenericValueRepository<T extends Value> extends MongoRepository<T, String> {
}

SpeedValueRepository.java

@Repository
public interface SpeedValueRepository extends GenericValueRepository<SpeedValue> {
}

And finally GenericControler.java

@Controller
public class GenericController<T extends Value> {

    private GenericServiceImpl<T> service;

    public GenericController(GenericServiceImpl<T> speedValueService) {
        this.service = speedValueService;
    }

    @GetMapping
    public List<T> getCurrencyValue() {
        return service.findAll();
    }

    @PostMapping
    public String create(@RequestBody T json) {

        T created = this.service.save(json);
        return "Added to DB: \n" + created.toString();
    }

and controller which extends GenericController

@RestController
@RequestMapping("api/values/speed")
public class SpeedValueControllerREST extends GenericController<SpeedValue>{

    @Autowired
    public SpeedValueControllerREST(SpeedValueService speedValueService) {
        super(speedValueService);
    }
}

This code doesn't work, I've been trying with many versions, but result was NPE or code didn't compile. I have to create many models, repositories, services like these above. Can you resolve that problem? Maybe I shoud do it in other way?

Answer 1

Finally, I solved this problem by:

https://stackoverflow.com/a/53406444/10474557

That was exactly what i was looking for

Answer 2

I did not understood your code, you are talking about generic, what i am assuming here is you are trying to create generic API for getting any/generic request (possibly JSON), save into MongoDB, Should be able to fetch the data with generic search query, update the data with generic selection criteria etc..

I am not sure how @MongoRepository will help in this regards, I will explan how i have achieved this generic behavior for our MongoCrud service - Pseudo code, rest you have to learn and implement -

1. Create connection and get the MongoClient for CRUD Operation - Docs https://api.mongodb.com/java/3.0/com/mongodb/MongoClient.html

2. Write Controller method to accept Request Body as String variable ( value would be json while making request ) to save, And validate if Document document = Document.parse(payload); if a document, then Save to particular collection using the MongoClient instance.

3. Write Controller method to accept Request Body as String variable ( value would be json while making request ), And validate it, and use MongoClient instance to query. Link for creating query json https://docs.mongodb.com/manual/tutorial/query-documents/

I hope this will help to reach your objective.