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etienne
 Post subject: New feature for Hibernate 3.1+:<Formula> inside <Se
PostPosted: Tue Sep 06, 2005 3:06 pm 
Senior
Senior

Joined: Tue Jan 11, 2005 5:03 pm
Posts: 137
Location: Montreal, Quebec
Hi Hibernate Developers,

Is it possible to ask for this new feature for Hibernate 3.1+ in JIRA?

I previously ask in theis forum (http://forum.hibernate.org/viewtopic.php?t=947145&highlight=) if it was possible to add the <formula> tag inside the <set> element (or any Collection).

I would need that to link 2 tables (parent->children) in a one-to-many relationship, because the primary key (parent) and the foreign key (child) are not in the same type! (CHAR vs NUMERIC). I work with a legacy database, and I cannot change the type of the column.

If I could use a <formula> inside the Set instead of declaring the <column> element, I could tell Hibernate to generate the inner join using the CONVERT(VARCHAR, column) command.

All my reading about making collection in a one-to-many tells me that there is no other way to make this mapping... And I need this mapping to be able to make a HQL left outer join between theses 2 tables.

Thanks.

Etienne.
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gavin
 Post subject:
PostPosted: Tue Sep 06, 2005 3:15 pm 
Hibernate Team
Hibernate Team

Joined: Tue Aug 26, 2003 12:50 pm
Posts: 5130
Location: Melbourne, Australia
AFAIK, this is already possible in HB 3.1. (Maybe even in 3.0.x.) Have you tried it?
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etienne
 Post subject:
PostPosted: Tue Sep 06, 2005 4:03 pm 
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Joined: Tue Jan 11, 2005 5:03 pm
Posts: 137
Location: Montreal, Quebec
Thanks Gavin,

according to the documentation of Hibernate 3.1 section 7.2, Map (Set and other collection) can be populate with theses attributes:
see: Hibernate 3.1b2 PDF documentation, Page 80.

Code:
<map
name="propertyName" (1)
table="table_name" (2)
schema="schema_name" (3)
lazy="true|extra|false" (4)
inverse="true|false" (5)
cascade="all|none|save-update|delete|all-delete-orphan" (6)
sort="unsorted|natural|comparatorClass" (7)
order-by="column_name asc|desc" (8)
where="arbitrary sql where condition" (9)
fetch="join|select|subselect" (10)
batch-size="N" (11)
access="field|property|ClassName" (12)
optimistic-lock="true|false" (13)
mutable="true|false" (14)
node="element-name|."
embed-xml="true|false"
>


The DTD of Hibernate 3.0.5 and 3.1 (same DTD header in 3.1beta2) shows that theses are the only element for a Set:

Code:
<!ELEMENT set (
   meta*,
   subselect?,
   cache?,
   synchronize*,
   comment?,
   key,
   (element|one-to-many|many-to-many|composite-element|many-to-any),
   loader?,sql-insert?,sql-update?,sql-delete?,sql-delete-all?,
   filter*
)>
   <!ATTLIST set name CDATA #REQUIRED>
   <!ATTLIST set access CDATA #IMPLIED>
   <!ATTLIST set table CDATA #IMPLIED>                                                <!-- default: name -->
   <!ATTLIST set schema CDATA #IMPLIED>                                             <!-- default: none -->
   <!ATTLIST set catalog CDATA #IMPLIED>                                             <!-- default: none -->
   <!ATTLIST set subselect CDATA #IMPLIED>
   <!ATTLIST set lazy (true|false|extra) #IMPLIED>
   <!ATTLIST set sort CDATA "unsorted">                                              <!-- unsorted|natural|"comparator class" -->
   <!ATTLIST set inverse (true|false) "false">
   <!ATTLIST set mutable (true|false) "true">
   <!ATTLIST set cascade CDATA #IMPLIED>
   <!ATTLIST set order-by CDATA #IMPLIED>                                              <!-- default: none -->
   <!ATTLIST set where CDATA #IMPLIED>                                                <!-- default: none -->
   <!ATTLIST set batch-size CDATA #IMPLIED>
   <!ATTLIST set outer-join (true|false|auto) #IMPLIED>
   <!ATTLIST set fetch (join|select|subselect) #IMPLIED>
   <!ATTLIST set persister CDATA #IMPLIED>   
   <!ATTLIST set collection-type CDATA #IMPLIED>                                          
   <!ATTLIST set check CDATA #IMPLIED>                                                <!-- default: none -->
   <!ATTLIST set optimistic-lock (true|false) "true">      <!-- only supported for properties of a class (not component) -->
   <!ATTLIST set node CDATA #IMPLIED>
   <!ATTLIST set embed-xml (true|false) "true">


I dont see where I could use the formula Tag. The formula tag is available for properties, many-to-one and one-to-one but not for any <Set> element. Also, the one-to-many element is declared without any sub-tag or formula attribut:

Code:
<!ELEMENT one-to-many EMPTY>
   <!ATTLIST one-to-many class CDATA #IMPLIED>
   <!ATTLIST one-to-many not-found (exception|ignore) "exception">
   <!ATTLIST one-to-many node CDATA #IMPLIED>
   <!ATTLIST one-to-many embed-xml (true|false) "true">
   <!ATTLIST one-to-many entity-name CDATA #IMPLIED>


Is there an other way to do this? Thanks a lot for helping me, and sorry if I didn't see something obvious,I am still searching to make it work.

regards,


Etienne.
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gavin
 Post subject:
PostPosted: Tue Sep 06, 2005 4:10 pm 
Hibernate Team
Hibernate Team

Joined: Tue Aug 26, 2003 12:50 pm
Posts: 5130
Location: Melbourne, Australia
Oh right, it is a one-to-many.

All you need is for <key> to accept <formula> as an alternative to <column>.

Hibernate does not currently support this, but it is probably reasonably straightforward to implement in AbstractCollectionPersister.

You could produce a patch for that.
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etienne
 Post subject:
PostPosted: Wed Sep 07, 2005 1:44 pm 
Senior
Senior

Joined: Tue Jan 11, 2005 5:03 pm
Posts: 137
Location: Montreal, Quebec
Thank Gavin,

could I have a small clue how to do this? What method should I look? I have checked AbstractEntityPersister to see how you manage the formulas and I must confess that it seems quite complexe.

I dont think I can patch AbstractCollectionPersister in a reasonnable time frame to make it works with formulas. If it can be part of Hibernate 3.1.1 or 3.2, I guess it is better for me to wait for it.

Thanks anyway.

Etienne.
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selliott1
 Post subject:
PostPosted: Mon Jan 07, 2008 1:07 pm 
Newbie

Joined: Wed Jun 14, 2006 6:43 am
Posts: 4
Any updates on this problem, as I too am trying to map a collection where the columns are of different types.

Having the the key accept a formula seems a good solution, but has anyone else got a different one.

Currently I am having to initialise the collection within the DAO for all the loaded parent objects.

Cheers
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