Spring boot JSON return infinite nested objects

Question

I have the following in my code:

CompanyEntity

@Entity
@Table(name = "company")
public class Company{
   @OneToMany(mappedBy = "company", cascade = CascadeType.ALL)
   @JsonUnwrapped
   private Set<User> users;
}

UserEntity

@Entity
@Table(name="user")
public class User{
    @ManyToOne(cascade = CascadeType.REFRESH)
    @JoinColumn(name="company_id")
    private Company company;
}

CompanyController

@GetMapping("/company")
public ResponseEntity<Object> getAllCompanies(){
    List<Company> allCompanies = companyService.findAll();
    return ResponseEntity.ok(allCompanies);

}

problem is when i call /company in the browser i am getting the users object including the company object. something like this

[
    {
        "id": 1,
        "name": "company",
        "users": [
            {
                "id": 14,
                "firstName": "Yamen",
                "lastName": "Nassif",
                "company": {
                    "id": 1,
                    "name": "company",
                    "users": [
                        {
                            "id": 14,
                            "firstName": "Yamen",
                            "lastName": "Nassif",
                            "company": {
                                "id": 1,
                                "name": "company",
                                "users": [

...

same goes when i getAllUsers companies and users are also exanding.

my database looks just fine.

and its endless and of course Stackoverflow error is in the console. How can i fix this ?

RaynerMDZ · Accepted Answer · 2021-05-31 02:51:14Z

3

You can use @JsonIgnore annotation to prevent this type of behavior. This usually happens with bidirectional mapping within your entities. It is caused by infinite recursion.

@Entity
@Table(name="user")
public class User{
    @ManyToOne(cascade = CascadeType.REFRESH)
    @JoinColumn(name="company_id")
    @JsonIgnore
    private Company company;
}

edited May 31, 2021 at 2:51

answered May 30, 2021 at 21:37

RaynerMDZ

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Comments

htshame · Accepted Answer · 2020-03-02 16:20:00Z

1

You have this error because of the infinite recursion.

Company has a link on User and User has a link on Company.

You have at least two options:

use @JsonManagedReference and @JsonBackReference annotation on the relation fields.
create a pair of DTOs and fill them manually with data from you entities.

e.g.

@GetMapping("/company")
public ResponseEntity<Object> getAllCompanies() {
    List<Company> allCompanies = companyService.findAll();
    List<CompanyDto> allCompanyDtoList = convertToCompanyDtoList(allCompanies);
    return ResponseEntity.ok(allCompanyDtoList );
}

Personally, I'd prefer the second option, since returning Entities is NOT a good practice.

edited Mar 2, 2020 at 16:20

answered Mar 2, 2020 at 16:09

htshame

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7 Comments

Yamen Nassif Over a year ago

i tried something different: removing @OneToMany(mappedBy = "company", cascade = CascadeType.ALL) from Company isn`t working and then i have a persistence error

Yamen Nassif Over a year ago

i mean removing the whole users object from Company, but something is getting broken.

Yamen Nassif Over a year ago

and i am not sure but wont allCompanies already break or will already be expanded even without JSONing it ?

htshame Over a year ago

No, acquiring allCompanies with the code you've provided in the question won't break anything. This error is about infinite loop when serializing entities to JSON which you return from you rest controller.

Yamen Nassif Over a year ago

ok thanks, i will try it. but how about removing one of the links from one entity? users from Company as an example ? how can i achieve that without an error ?

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