one-to-many problem

jasonhomenet · **Posted:** Thu Feb 19, 2004 6:48 am

hi all,
I have got a problem on creating the mapping file for my class, after read the documentation, i found a <composite-id> function, but i am not sure how can I use it to write my mapping file for my class.

2 Tables of my Database, which have one-to-many relation and one of the table has 3 keys. AuctionItem one-to-many BidOnItemLog.

AuctionItem Table
=================
auctionid *
createdate
starttime
endtime
startprice
winner

BidOnItemLog Table
=================
auctionid * (FK)
userid *
datetime *
price

My tables relation , the column in BidOnItemLog Table "auctionid" is a foreign key which is related to the primary key of the AuctionItem Table.
and "userid" and "datetime" are the primary key of BidOnItemLog Table.

Mapping file of AuctionItem Domain Object

Code:

<hibernate-mapping> 
   <class name="com.twofi.auction.objects.AuctionItem" table="auctionitem"> 
      <id name="auctionid" column="auctionid" unsaved-value="any"> 
         <generator class="increment" />
      </id>
      <property name="createdate" column="createdate" />
      <property name="starttime" column="starttime" />
      <property name="endtime" column="endtime" />
      <property name="startprice" column="startprice" />
      <property name="winner" column="winner" />
   </class> 
</hibernate-mapping>

Can anyone please kindly to teach me, how can I define the mapping for the BidOnItemLog Objects ?? Thank you very much ! : )

emmanuel · **Posted:** Thu Feb 19, 2004 7:01 am

Something like that, but read the tutorials and such materials

Code:

<hibernate-mapping>
   <class name="com.twofi.auction.objects.AuctionItem" table="auctionitem">
      <id name="auctionid" column="auctionid" unsaved-value="any">
         <generator class="increment" />
      </id>
      <property name="createdate" column="createdate" />
      <property name="starttime" column="starttime" />
      <property name="endtime" column="endtime" />
      <property name="startprice" column="startprice" />
      <property name="winner" column="winner" />
      <set name="logs" inverse="true">
         <key>
           <column name="auctionid"/>
         </key>

         <one-to-many class="BidOnItemLog"/>
       </set>
   </class>
</hibernate-mapping> 

<hibernate-mapping>
   <class name="com.twofi.auction.objects.BidOnItemLog" table="auctionitem">
      <composite-id unsaved-value="any">
         <key-many-to-one column="auctionid" class="Auction"/>
         <key-property name="userid" column="userid"/>
         <key-property name="datetime" column="datetime"/>
      </composite-id>
      <property name="createdate" column="createdate" />
      <property name="starttime" column="starttime" />
      <property name="endtime" column="endtime" />
      <property name="startprice" column="startprice" />
      <property name="winner" column="winner" />
      <set name="logs" inverse="true">
         <key>
           <column name="auctionid"/>
         </key>

         <one-to-many class="BidOnItemLog"/>
       </set>
   </class>
</hibernate-mapping> 

jasonhomenet · **Posted:** Thu Feb 19, 2004 7:09 am

thanks emmanuel ! You have gave me a big hint.
I'll try my best to understand it.