Recursive JSON input causes SyntaxError: Unexpected end of JSON input at JSON.parse

Question

I have been at it for hours and I can seem to tackle the problem. I have two entities Products and Customer where, a customer can have one product whereas a product may have many customers. In my SQL SERVER Management studio, the primary key of the Product table rests as a foreign key in the Customer table.

I have shown the two entites in the code below. The problem is that the customer "c" is recursively appended to the "myproducts" which is the mappedBy attribute in the JSON that is shown when I check the console on my browser window. (Please see the nested objects "myproducts" and "c" in the error below)

I am using the GET method API to display the customers on the screen.

Products.java

@Entity
@Table(name="NewProductDetails")
public class Products{

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "p_id")
    private int productId;

    @Size(max=65)
    @Column(name = "p_name")
    private String name;

    @Column(name = "p_price")
    private int price;


    @OneToMany(fetch = FetchType.LAZY,
              cascade = CascadeType.ALL,
              mappedBy = "myproduct")
    public  Set<Customer> c;

    public Products() {

    }


    public Products(String p_name, int p_price) {
        this.name = p_name;
        this.price = p_price;
    }

    public long getproductId() {
        return productId;
    }

    public void setproductId(int id) {
        this.productId = id;
    }

    public void setPName(String p_name) {
        this.name = p_name;
    }

    public String getPName() {
        return this.name;
    }

    public void setPrice(int p_price ) {
        this.price  = p_price ;
    }

    public int getPrice() {

        return this.price;
    }

}

ProductController.java

@CrossOrigin(origins = "http://localhost:4200")
@RestController
@RequestMapping("/api")
public class ProductController {

    @Autowired
    ProductRepository productRepository;

    @GetMapping("/product")
    public List<Products> getAllProducts(){
        System.out.println("Get All the product .... ");

        List<Products> products = new ArrayList<>();
        productRepository.findAll().forEach(products :: add);

        return products;
    }

    @GetMapping("/product/{id}")
    public ResponseEntity<Products> findByProductId(@PathVariable("p_id") Long p_id ){
        Optional<Products> prod_ = productRepository.findByProductId(p_id);
        return ResponseEntity.ok(prod_.get());
    }


    @PostMapping(value = "/product")
    public Products postProducts(@RequestBody Products product) {
        Products _product = productRepository.save(new Products(product.getPName(), product.getPrice() ));
        return _product;
    }
}

ProductRepository.java

@Repository
public interface ProductRepository extends CrudRepository<Products, Long>{

    Optional<Products> findByProductId(Long p_id);
}

CustomerRepository.java

@CrossOrigin(origins = "http://localhost:4200")
@RestController
@RequestMapping("/api")
public class CustomerController {

    @Autowired
    CustomerRepository repository;

    @GetMapping("/customer")
    public List<Customer> getAllCustomers() {
        System.out.println("HOOHAAH Get all Customers...");

        List<Customer> customers = new ArrayList<>();
        repository.findAll().forEach(customers::add);
        System.out.println(customers);
        return customers;
    }

    @GetMapping("/customer/{id}")
    public ResponseEntity<Customer> findById(@PathVariable("id") Long Id){
            Optional<Customer> cust_ = repository.findById(Id);
            return ResponseEntity.ok(cust_.get());
    }

    @PostMapping(value = "/customer")
    public Customer postCustomer(@RequestBody Customer customer) {

        Customer _customer = repository.save(new Customer(customer.getName(), customer.getAge(), customer.getProduct()));
        return _customer;
    }

    @DeleteMapping("/customer/{id}")
    public ResponseEntity<String> deleteCustomer(@PathVariable("id") long id) {
        System.out.println("Delete Customer with ID = " + id + "...");

        repository.deleteById(id);

        return new ResponseEntity<>("Customer has been deleted!", HttpStatus.OK);
    }

    @DeleteMapping("/customer")
    public ResponseEntity<String> deleteAllCustomers() {
        System.out.println("Delete All Customers...");

        repository.deleteAll();

        return new ResponseEntity<>("All customers have been deleted!", HttpStatus.OK);
    }

    @GetMapping(value = "customer/age/{age}")
    public List<Customer> findByAge(@PathVariable int age) {

        List<Customer> customers = repository.findByAge(age);
        return customers;
    }


    @PutMapping("/customer/{id}")
    public ResponseEntity<Customer> updateCustomer(@PathVariable("id") long id, @RequestBody Customer customer) {
        System.out.println("Update Customer with ID = " + id + "...");

        Optional<Customer> customerData = repository.findById(id);

        if (customerData.isPresent()) {
            Customer _customer = customerData.get();
            _customer.setName(customer.getName());
            _customer.setAge(customer.getAge());
            _customer.setActive(customer.isActive());
            return new ResponseEntity<>(repository.save(_customer), HttpStatus.OK);
        } else {
            return new ResponseEntity<>(HttpStatus.NOT_FOUND);
        }
    }
}

main

@SpringBootApplication
public class SpringRestMySqlApplication implements CommandLineRunner {


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

    @Override
    public void run(String... args) throws Exception {



        //Create Product Instance
        Products prods = new Products();

        //Create Customer instance
        Customer custs = new Customer();


    }

}

Error shown in browser SyntaxError: Unexpected end of JSON input at JSON.parse () at XMLHttpRequest.onLoad

"[{"id":6,"name":"Asma","age":18,"active":true,"myproduct":{"productId":2,"price":4,"c":[{"id":6,"name":"Asma","age":18,"active":true,"myproduct":{"productId":2,"price":4,"c":[{"id":6,.....

Error in Server log

    at com.fasterxml.jackson.databind.ser.std.BeanSerializerBase.serializeFields(BeanSerializerBase.java:719) ~[jackson-databind-2.9.6.jar:2.9.6]
    at com.fasterxml.jackson.databind.ser.BeanSerializer.serialize(BeanSerializer.java:155) ~[jackson-databind-2.9.6.jar:2.9.6]
    at com.fasterxml.jackson.databind.ser.BeanPropertyWriter.serializeAsField(BeanPropertyWriter.java:727) ~[jackson-databind-2.9.6.jar:2.9.6]
    at com.fasterxml.jackson.databind.ser.std.BeanSerializerBase.serializeFields(BeanSerializerBase.java:719) ~[jackson-databind-2.9.6.jar:2.9.6]
    at com.fasterxml.jackson.databind.ser.BeanSerializer.serialize(BeanSerializer.java:155) ~[jackson-databind-2.9.6.jar:2.9.6]
    at com.fasterxml.jackson.databind.ser.std.CollectionSerializer.serializeContents(CollectionSerializer.java:145) ~[jackson-databind-2.9.6.jar:2.9.6]
    at com.fasterxml.jackson.databind.ser.std.CollectionSerializer.serialize(CollectionSerializer.java:107) ~[jackson-databind-2.9.6.jar:2.9.6]
    at com.fasterxml.jackson.databind.ser.std.CollectionSerializer.serialize(CollectionSerializer.java:25) ~[jackson-databind-2.9.6.jar:2.9.6]
    at com.fasterxml.jackson.databind.ser.BeanPropertyWriter.serializeAsField(BeanPropertyWriter.java:727) ~[jackson-databind-2.9.6.jar:2.9.6]
    at com.fasterxml.jackson.databind.ser.std.BeanSerializerBase.serializeFields(BeanSerializerBase.java:719) ~[jackson-databind-2.9.6.jar:2.9.6]
    at com.fasterxml.jackson.databind.ser.BeanSerializer.serialize(BeanSerializer.java:155) ~[jackson-databind-2.9.6.jar:2.9.6]
    at com.fasterxml.jackson.databind.ser.BeanPropertyWriter.serializeAsField(BeanPropertyWriter.java:727) ~[jackson-databind-2.9.6.jar:2.9.6]
    at com.fasterxml.jackson.databind.ser.std.BeanSerializerBase.serializeFields(BeanSerializerBase.java:719) ~[jackson-databind-2.9.6.jar:2.9.6]
    at com.fasterxml.jackson.databind.ser.BeanSerializer.serialize(BeanSerializer.java:155) ~[jackson-databind-2.9.6.jar:2.9.6]
    at com.fasterxml.jackson.databind.ser.std.CollectionSerializer.serializeContents(CollectionSerializer.java:145) ~[jackson-databind-2.9.6.jar:2.9.6]
    at com.fasterxml.jackson.databind.ser.std.CollectionSerializer.serialize(CollectionSerializer.java:107) ~[jackson-databind-2.9.6.jar:2.9.6]
    at com.fasterxml.jackson.databind.ser.std.CollectionSerializer.serialize(CollectionSerializer.java:25) ~[jackson-databind-2.9.6.jar:2.9.6]

........

Try adding `implements Serializable` in you model class. (Prodducts.java) — miiiii, Oct 09 '19 at 07:25
I did that and it did not work. Also, I do not see how serializable will help in my case. — Asma Rahim Ali Jafri, Oct 09 '19 at 07:27
suggested `implements Serializable` as I didn't see in the post itself. However it won't help much in that. `@JsonIgnore` on `Products.java` should do the job. — miiiii, Oct 09 '19 at 07:36
The post has been edited here is the link to the full log just in case. https://pastebin.com/raw/xD0MjfBk — Asma Rahim Ali Jafri, Oct 09 '19 at 07:39
This is not, what needed... **the first line** .. that tells the error/exception message. These are just stack trace. — miiiii, Oct 09 '19 at 07:39
You should also see these two posts.. https://stackoverflow.com/a/18288939/6446770 and https://stackoverflow.com/questions/3325387/infinite-recursion-with-jackson-json-and-hibernate-jpa-issue — miiiii, Oct 09 '19 at 07:40

score 0 · Accepted Answer · answered Oct 09 '19 at 08:14

I resolved the error using @JsonIgnoreProperties() in each of the entities (Products and Customers) and the circular dependency vanished.

I found help on this awesome blog to solve recursive circular dependency in JSON by following it's approach # 3 http://springquay.blogspot.com/2016/01/new-approach-to-solve-json-recursive.html

Recursive JSON input causes SyntaxError: Unexpected end of JSON input at JSON.parse

1 Answers1