I have made some changes to my MYSQL database so that a Product can have multiple Images associated with it (One to Many), however since making this change I am seeing some weird behaviour and the program throws a StackOverflow Exception. It seems as if the program is stuck in a continuous loop before crashing and throwing the error.
My model classes are structured as follows:
@Entity
@Table(name="products")
public class Products {
public Products(String name, String price, String added_on, String category_id, String image_name, String description, List<ImageModel> imageModel) {
super();
this.name = name;
this.price = price;
this.added_on = added_on;
this.category_id = category_id;
this.image_name = image_name;
this.description = description;
this.imageModel = imageModel;
}
public Products(String name, String price, String added_on, String category_id, String description) {
super();
this.name = name;
this.price = price;
this.added_on = added_on;
this.category_id = category_id;
this.description = description;
}
public Products() {}
@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
private long id;
private String name;
private String price;
private String added_on;
private String category_id;
private String image_name;
private String description;
private String image_id;
@ManyToOne(optional=false)
@JoinColumn(name = "category_id", insertable=false, updatable=false)
private Category category;
@OneToMany(mappedBy = "product")
private List<ImageModel> imageModel;
// Getters & Setters
This class is then linked to ModelImage as follows:
@Entity
@Table(name = "image_table")
public class ImageModel {
public ImageModel() {
super();
}
public ImageModel(String name, String type, byte[] picByte, Products product) {
this.name = name;
this.type = type;
this.picByte = picByte;
this.product = product;
}
public ImageModel(String name, String type, byte[] picByte) {
this.name = name;
this.type = type;
this.picByte = picByte;
}
@Id
@Column(name = "id")
@GeneratedValue(strategy = GenerationType.IDENTITY)
private Long id;
@Column(name = "name")
private String name;
@Column(name = "type")
private String type;
// image bytes can have large lengths so we specify a value
// which is more than the default length for picByte column
@Column(name = "picByte", length = 10000)
private byte[] picByte;
@ManyToOne
@JoinColumn(name="product_id")
private Products product;
// Getters Setters
When I add a product, the following code executes and seems to add everything as expected:
@PostMapping(value = "imageUploadMultiple")
public ResponseEntity<ImageResponse> addProductAndImages(@RequestParam("imageFiles") MultipartFile[] files, @RequestParam("productName") String productName, @RequestParam("productDescription") String productDescription, @RequestParam("productPrice") String productPrice, @RequestParam("categoryId") String categoryId) throws IOException {
// Need to save product first then get the id and save all images with the productId
Products products = productService.addProduct(productName, productDescription, productPrice, categoryId);
Arrays.asList(files).stream().forEach(file -> {
ImageModel img = null;
try {
img = new ImageModel(file.getOriginalFilename(), file.getContentType(), compressBytes(file.getBytes()), products);
imageRepository.save(img);
} catch (IOException e) {
e.printStackTrace();
}
});
return ResponseEntity.ok().build();
}
This endpoint accepts multiple images and form data which corresponds to the image(Product Details etc)
However, the problem occurs when I call the endpoint to get all products based on a particular categoryId:
@RequestMapping(value = "getProductsByCategory", produces = MediaType.APPLICATION_JSON_VALUE)
public List<Products> getProductsByCategory(@RequestBody HashMap<String, String> request) {
String category_id = request.get("cat_id");
List<Products> list = productService.getProductsByCategory(category_id);
return list;
}
This then calls into the service class which then calls the repository code:
@Query("Select pro FROM Products pro WHERE pro.category_id=:cat_id")
List<Products> getByCategoryId(@Param("cat_id")String cat_id);
When I run the app in debug mode, I get the following data (At this time there is only one product for that particular categoryID):
Notice how 'ImageModel' is of a PersistentBag type. When i dig deeper into this I get the mapped images to the particular product. In this instance there is 4 product images for the product. When i dig even deeper I notice there is just a continuous loop:
The error is as follows
java.lang.StackOverflowError: null
at java.lang.ClassLoader.defineClass1(Native Method) ~[na:1.8.0_251]
at java.lang.ClassLoader.defineClass(ClassLoader.java:756) ~[na:1.8.0_251]
at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:142) ~[na:1.8.0_251]
at java.net.URLClassLoader.defineClass(URLClassLoader.java:468) ~[na:1.8.0_251]
at java.net.URLClassLoader.access$100(URLClassLoader.java:74) ~[na:1.8.0_251]
at java.net.URLClassLoader$1.run(URLClassLoader.java:369) ~[na:1.8.0_251]
Could not write JSON: Infinite recursion (StackOverflowError); nested exception is com.fasterxml.jackson.databind.JsonMappingException: Infinite recursion (StackOverflowError) (through reference chain: com.youtube.ecommerce.model.Products["imageModel"]->org.hibernate.collection.internal.PersistentBag[0]->com.youtube.ecommerce.model.ImageModel["product"]->com.youtube.ecommerce.model.Products["imageModel"]->org.hibernate.collection.internal.PersistentBag[0]->com.youtube.ecommerce.model.ImageModel["product"]->com.youtube.ecommerce.model.Products["imageModel"]->org.hibernate.collection.internal.PersistentBag[0]->com.youtube.ecommerce.model.ImageModel["product"]->com.youtube.ecommerce.model.Products["imageModel"]->org.hibernate.collection.internal.PersistentBag[0]->com.youtube.ecommerce.model.ImageModel["product"]->com.youtube.ecommerce.model.Products["imageModel"]->org.hibernate.collection.internal.PersistentBag[0]
The error just keeps going and going so i didnt post the full thing but it continuously says the same thing over and over again.
Im really struggling to understand whats gone wrong here!!
