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POHibernate: Double entries in ManyToMany Jointable
 

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  1. POHibernate: Double entries in ManyToMany Jointable
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    <p>I have a ManyToMany Relation in my Domain Object and i want to user double entries in the JoinTable. At the moment my code looks like this:</p> <pre><code>@ManyToMany(cascade = {CascadeType.ALL}) @JoinTable(name="Purchase_BasicProduct", joinColumns={@JoinColumn(name="order_number")}, inverseJoinColumns={@JoinColumn(name="id")}) private Set&lt;BasicProduct&gt; BasicProducts = new HashSet&lt;BasicProduct&gt;(); </code></pre> <p>instead of the Set I want to use a List to enable double entries JoinTable. But when I use a list and I store the same entry the second time i get this error</p> <pre><code>ERROR: duplicate key value violates unique constraint "purchase_basicproduct_pkey" DETAIL: Key (order_number, id)=(703, 4) already exists. </code></pre> <p>is there a possibility to deactivate this unique constraint in the jointable. or would it be better to use a third column to store the amount of occurrences of an entry? and if this is the case, how can I store this third column and afterwards query for this?</p> <p>Edit: for saving I use a generic Method. here is the code. T is substituted by an Object called Purchase. This stores all informations of an Purchase, and the Set with the ManyToMany association.</p> <pre><code>@Transactional public void createEntity(T entity) throws DAOException { if(entity == null) { throw new IllegalArgumentException("entity mustn't be null!"); } try{ em.persist(entity); } catch(IllegalStateException e) { throw new DAOException("Can't update Entity!", e); } catch(TransactionRequiredException e) { throw new DAOException("Can't update Entity!", e); } catch(EntityExistsException e) { throw new DAOException("Can't update Entity!", e); } } </code></pre>
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    1. USpinkpanther
    1. USflo8433
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    1. COcan u show the code which you used to save
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    2. COi have added the code to my post
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A row detail

Detail views are divided into sections. All the information in the data section comes from columns in the selected row. The other sections display data from other, related rows.

Related data can be related in a to-one or a to-many fashion. Captions of data related in a to-many fashion link to a list view showing a filtered view of the table.

Try moving around until you find a non-empty to-many entry and click on the label to get to one. You can move back to the root by clicking on the database name in the header.

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