Spring boot Rest create a category which can reference to another category or not - spring

Question

I have an entity class
public class CategoryEntity implements Serializable {
#Getter(AccessLevel.NONE)
#Setter(AccessLevel.NONE)
private static final long serialVersionUID = 1L;
#Id
#GeneratedValue(strategy= GenerationType.AUTO)
private Long id;
#Column(length = 30, nullable = false)
private String categoryKeyId;
#Column(nullable = false)
private String name;
//Here mappedBy indicates that the owner is in the other side
#OneToMany(fetch = FetchType.EAGER, mappedBy = "category", cascade = CascadeType.ALL)
private List<ProductEntity> products;
#ManyToOne(optional = true, fetch = FetchType.LAZY)
private CategoryEntity parent;
// allow to delete also subcategories
#OneToMany(mappedBy="parent", cascade = CascadeType.ALL)
private List<CategoryEntity> subCategories;
}
this class generates this SQL code :
CREATE TABLE `categories` (
`id` bigint(20) NOT NULL,
`category_key_id` varchar(30) COLLATE utf8_unicode_ci NOT NULL,
`name` varchar(255) COLLATE utf8_unicode_ci NOT NULL,
`parent_id` bigint(20) DEFAULT NULL,
PRIMARY KEY (`id`),
KEY `FKsaok720gsu4u2wrgbk10b5n8d` (`parent_id`)
) ENGINE=MyISAM DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci;
So far, so good it's perfectly what i'm expecting. My issue concerns how to create a new category.
My DTO layer is :
#Getter #Setter
public class CategoryDto implements Serializable {
#Getter(AccessLevel.NONE)
#Setter(AccessLevel.NONE)
private static final long serialVersionUID = 1L;
private long id;
private int parentCategoryId;
private String categoryKeyId;
private String name;
private List<CategoryDto> subCategories;
private CategoryDto parentCategory;
}
I also created 2 Rest Model for creating categories one for the request and the other for the response.
I need to provide a json as entry with the name and the parent category id:
#Getter #Setter
public class CategoryCreateRequestModel {
private String name;
private int parentCategory;
}
And i retrieve a json as output :
#Getter #Setter
public class CategoryCreateRest {
private String categoryKeyId;
private String name;
private CategoryCreateRest parentCategory;
}
My createCategory method returns the output result i expect and takes a CategoryCreateRequestModel as input.
#PostMapping(
consumes = { MediaType.APPLICATION_XML_VALUE, MediaType.APPLICATION_JSON_VALUE },
produces = { MediaType.APPLICATION_XML_VALUE, MediaType.APPLICATION_JSON_VALUE }
)
public CategoryCreateRest createCategory(#RequestBody CategoryCreateRequestModel categoryCreateRest) throws Exception {
CategoryCreateRest returnValue = new CategoryCreateRest();
if( categoryCreateRest.getName().isEmpty())
throw new NullPointerException(ErrorMessages.MISSING_REQUIRED_FIELDS.getErrorMessage());
ModelMapper modelMapper = new ModelMapper();
CategoryDto categoryDto = modelMapper.map(categoryCreateRest, CategoryDto.class);
CategoryDto createdCategory = categoryService.createCategory(categoryDto);
returnValue = modelMapper.map(createdCategory, CategoryCreateRest.class);
return returnValue;
}
My service layer :
#Override
public CategoryDto createCategory(CategoryDto categoryDto) {
// check if category name and parentId are identicals
if (categoryRepository.findByName(categoryDto.getName()) != null)
throw new ApplicationServiceException("Record already in Database");
ModelMapper modelMapper = new ModelMapper();
CategoryEntity categoryEntity = modelMapper.map(categoryDto, CategoryEntity.class);
// generate categoryKeyId
String categoryKeyId = utils.generateCategoryKeyId(30);
categoryEntity.setCategoryKeyId(categoryKeyId);
CategoryEntity storedCategory = categoryRepository.save(categoryEntity);
CategoryDto returnValue = modelMapper.map(storedCategory, CategoryDto.class);
return returnValue;
}
When i set a new category for example:
{
"name": "catName",
"parentCategoryId": 12
}
or
{
"name": "catName",
"parentCategoryId": null
}
I obtain a 500 error message : could not execute statement; SQL [n/a]; constraint [PRIMARY]; nested exception is org.hibernate.exception.ConstraintViolationException: could not execute statement"
Apparently I have issues with the primary key and I don't see what is going wrong. I should not need to pass an id to this json because it should be automatically generated.