Hibernate deletion referential integrity constraint violation on many to many association - spring

Question

I am trying to use Hibernate to remove an entity however I get an error: Cannot delete or update a parent row: a foreign key constraint fails
The setup is that I have an abstract class A and two classes (B and C) which extend A. B contains a list of C's (unidirectional relationship). And there is a function to delete A by its ID.
Note: Stuff has been removed for brevity.
#Entity
public class B extends A {
#ManyToMany(fetch = FetchType.EAGER)
#JoinTable(
joinColumns = #JoinColumn(name = "B_A_id"),
inverseJoinColumns = #JoinColumn(name = "C_A_id"))
List<C> cList;
}
#Entity
public class C extends A {
(no reference to B)
}
The issue is that when the deleteAByFixedId is called where A is a C, it tries to delete the C before it deletes the B which references it and therefore I get a foreign key constraint failure.
What am I doing wrong?

Answer 1

The answer will still be updated.
Links:
The best way to use the #ManyToMany annotation with JPA and Hibernate
Hibernate Inheritance Mapping
#ManyToMany
Unidirectional example:
User.java
#Entity
public class User {
#Id
#GeneratedValue
#Column(name = "user_id")
private long id;
...
#ManyToMany(fetch = FetchType.LAZY, cascade = CascadeType.ALL)
#JoinTable(name = "user_role", joinColumns = #JoinColumn(name = "user_id"), inverseJoinColumns = #JoinColumn(name = "role_id"))
private Set<Role> roles = new HashSet<>();
public void addRoles(Role role) {
roles.add(role);
}
public void removeRoles(Role role) {
roles.remove(role);
}
}
Role.java
#Entity
public class Role {
#Id
#GeneratedValue
#Column(name = "role_id")
private int id;
#Column(name = "role")
private String role;
}
Bidirectional example:
Trader.java:
#Data
#AllArgsConstructor
#NoArgsConstructor
#Entity
#ToString(exclude = "stockmarkets")
#Table(name = "trader")
public class Trader {
#Id
#GeneratedValue
#Column(name = "trader_id")
private Long id;
#Column(name = "trader_name")
private String traderName;
#ManyToMany(fetch = FetchType.LAZY,
cascade = {
CascadeType.PERSIST,
CascadeType.MERGE
})
#JoinTable(name = "TRADER_STOCKMARKET",
joinColumns = { #JoinColumn(name = "trader_id") },
inverseJoinColumns = { #JoinColumn(name = "stockmarket_id") })
private Set<Stockmarket> stockmarkets = new HashSet<>();
/*
We need to add methods below to make everything work correctly
*/
public void addStockmarket(Stockmarket stockmarket) {
stockmarkets.add(stockmarket);
stockmarket.getTraders().add(this);
}
public void removeStockmarket(Stockmarket stockmarket) {
stockmarkets.remove(stockmarket);
stockmarket.getTraders().remove(this);
}
}
Stockmarket.java
#Data
#AllArgsConstructor
#NoArgsConstructor
#Entity
#ToString(exclude = "traders")
#Table(name = "stockmarket")
public class Stockmarket{
#Id
#GeneratedValue
#Column(name = "stockmarket_id")
private Long id;
#Column(name = "stockmarket_name")
private String stockmarketName;
#ManyToMany(mappedBy="stockmarkets")
private Set<Trader> traders = new HashSet<>();
/*
We need to add methods below to make everything work correctly
*/
public void addTrader(Trader trader) {
traders.add(trader);
trader.getStockmarkets().add(this);
}
public void removeTrader(Trader trader) {
traders.remove(trader);
trader.getStockmarkets().remove(this);
}
}