'Transaction is not active' after receiving error for not being able to delete

Question

Guys tried to mount a crud for study and I came across the following situation.

I’m using JPA and hibernate.

When trying to delete a record that has reference in another table is launched an Exception saying that you can not delete pq has reference, until ai ok.

After this Exception appears if I try to add another item appears the same exception that showed when I tried to delete and just below 'Transaction is not active' what may be happening?

DAO

public T inserir(T entity) throws Exception {
    try {
        manager.getTransaction().begin();
        manager.persist(entity);
        manager.getTransaction().commit();          
    } catch (Exception e) {
        manager.getTransaction().rollback();
    }
    return entity;
}`

public void excluir(T entity) {
    try {
        manager.getTransaction().begin();
        manager.remove(entity);
        manager.getTransaction().commit();
    } catch (Exception e) {
        manager.getTransaction().rollback();
    }
}

RN

public Item inserir(Item item){
    try {
        return geralDAO.inserir(item);
    } catch (Exception e) {
        System.err.println(e.getMessage());
        return null;
    }       
}

public void excluir(Item item){
    try {
        geralDAO.excluir(item);

    } catch (Exception e) {
        System.err.println("Erro ao deletar", e.getMessage());          
    }       
}

Answer 1

You’re probably creating the factory and the manager in the construtor, but every operation must be closed to conexão. The "correct" implementation would be to create Factory and manager in each method, and close after operation.

Ex:

public void setProdutos(ProdutosVO produto) throws Exception{
    try {
        EntityManagerFactory factory = Persistence.createEntityManagerFactory("model");
        EntityManager manager = factory.createEntityManager();

        manager.getTransaction().begin();    
        manager.persist(produto);
        manager.getTransaction().commit();  

    } catch (Exception e) { 
        throw new Exception(e);
    }finally {
        manager.close();
        factory.close();
    }
}