DataNucleus Enhancer在LongIdentity上失败。 （datanucleus-maven-plugin 5.0.2）

Question

I was trying to create composite PK as follows for many-to-many-attributed relationship as documented here : but could not enhance when I use LongIdentity . Is the current DataNucleus Enhancer not compatible with it?

@PersistenceCapable(identityType = IdentityType.APPLICATION, cacheable = "false", detachable = "true",
    objectIdClass = CompanyProduct.PK.class)
public class CompanyProduct implements Serializable {

private static final long serialVersionUID = -7578808257727591074L;

@PrimaryKey
private Company company; // PK
@PrimaryKey
private Product product; // PK
...

public static class PK implements Serializable {

    private static final long serialVersionUID = -2090216333556951760L;
    public LongIdentity company; // Use same name as CompanyProduct field
    public LongIdentity product; // Use same name as CompanyProduct field

    public PK() {
    }

    public PK(String s) {
        StringTokenizer st = new StringTokenizer(s, "::");
        this.company = new LongIdentity(Company.class, st.nextToken());//
        this.product = new LongIdentity(Product.class, st.nextToken());//
    }

    @Override
    public String toString() {
        return (company.toString() + "::" + product.toString());
    } 
...

Product.java

@PersistenceCapable(identityType = IdentityType.APPLICATION, cacheable = "false", detachable = "true")
public class Product implements Serializable {

private static final long serialVersionUID = 8269335445554701873L;


@PrimaryKey
@Persistent(valueStrategy = IdGeneratorStrategy.IDENTITY)
long id;
@Persistent(mappedBy = "product")
private Set<CompanyProduct> companyProducts = new HashSet<>();
  ...

Company.java

@PersistenceCapable(identityType = IdentityType.APPLICATION, cacheable = "false", detachable = "true")
public class Company implements Serializable {

private static final long serialVersionUID = 6364869685797117033L;
@PrimaryKey
@Persistent(valueStrategy = IdGeneratorStrategy.IDENTITY)
//private 
long id;
@Persistent(mappedBy = "company")
private Set<CompanyProduct> companyProducts = new HashSet<>();

What am I doing wrong? datanucleus-maven-plugin version is 5.0.2 and datanucleus-core version is 5.1.6.

Answer 1

Based on the discussion and my trial on this case of deciding on which identity to use, I found it convenient to continue with the Application identity by adding a single field to the intermediate class to be its Application identity (generated value). With these I don't need to write the PK Class manually. Hence, I have my code as follows;

CompanyProduct.java (many_to_many_attributed)

@PersistenceCapable(identityType = IdentityType.APPLICATION, cacheable = "false", detachable = "true")
public class CompanyProduct implements Serializable {

private static final long serialVersionUID = -7578808257727591074L;

@PrimaryKey
@Persistent(valueStrategy = IdGeneratorStrategy.IDENTITY)
long id;
@Persistent
private Company company;
@Persistent
private Product product; 

...

Company.java

@PersistenceCapable(identityType = IdentityType.APPLICATION, cacheable = "false", detachable = "true")
public class Company implements Serializable {

private static final long serialVersionUID = 6364869685797117033L;

@PrimaryKey
@Persistent(valueStrategy = IdGeneratorStrategy.IDENTITY)
long id;
@Persistent(mappedBy = "company")
private Set<CompanyProduct> companyProducts = new HashSet<>();

...

Product.java

@PersistenceCapable(identityType = IdentityType.APPLICATION, cacheable = "false", detachable = "true")
public class Product implements Serializable {

private static final long serialVersionUID = 8269335445554701873L;

@PrimaryKey
@Persistent(valueStrategy = IdGeneratorStrategy.IDENTITY)
long id;
@Persistent(mappedBy = "product")
private Set<CompanyProduct> companyProducts = new HashSet<>();
...

This is what I have settled for now unless one advised me against the use of "Application identity". Thanks to @Billy and @DN1