I am a new bie to the world of hibernate could you please advise , I was going through one to one relationship in Hibernate,
As per my analysis , one to one hibernate relationships can be established by three ways..
1)Through Join concept
2)Same primary key in both the tables
3)Primary key and foriegn key relationship in both the tables
Please advise , the above three ways to achieve the one to one mapping is correct or I am missing something then please advise, and also please advise that the below hbm mapping files that I am using are correct one.if not then please advise.
1) Through Join concept :-
One way to achieve to one to one relationship is by joining concept , following xml is being used for that
<hibernate-mapping>
<class name="mypack.Person" table="person21">
<id name="personId" type="int">
<generator class="increment">
</generator>
</id>
<property name="name"/>
<join table="personAddress">
<key column="personId"/>
<many-to-one name="address" class="mypack.Address" column="addressId" unique="true" cascade="all"/>
</join>
</class>
<class name="mypack.Address" table="address21">
<id name="id" column="addressId" type="int">
<generator class="increment"/>
</id>
<property name="city"/>
<property name="state"/>
</class>
</hibernate-mapping>
2) Same primary key in both the tables :-
Using same primary key in both the tables , following hbm is being used for that
<class name="mypack.Address" table="address31">
<id name="id" column="addressId" type="int">
<generator class="increment"/>
</id>
<property name="city"/>
<property name="state"/>
</class>
<class name="mypack.Person" table="person31">
<id name="personId" type="int">
<generator class="foreign">
<param name="property">address</param>
</generator>
</id>
<property name="name"/>
<one-to-one name="address" class="mypack.Address"/>
</class>
</hibernate-mapping>
3)Primary key and foriegn key relationship in both the tables :-
Primary key in one table and foriegn key in another table. below is the hbm for this
<hibernate-mapping>
<class name="mypack.Person">
<id name="personId" type="int">
<generator class="increment"/>
</id>
<property name="name"/>
<many-to-one name="address" class="mypack.Address" column="addressId" unique="true" cascade="all"/>
</class>
<class name="mypack.Address">
<id name="id" column="addressId" type="int">
<generator class="increment"/>
</id>
<property name="city"/>
<property name="state"/>
</class>
</hibernate-mapping>
folks please advise.
I really think that join table is overkill here for a one-to-one mapping. For the other 2 solutions, please take a look at the following Hibernate documentation, everything is explained : http://docs.jboss.org/hibernate/orm/3.3/reference/en/html/mapping.html#mapping-declaration-onetoone.
For your second mapping (primary key association), both entities need to define a one-to-one mapping and one side of the relation also needs to specify the attribute constrained="true".
This is how I would write your second mapping :
<class name="mypack.Person" table="PERSONS">
<id name="id" type="int" column="PERSON_ID">
<generator class="increment"/>
</id>
<property name="name" type="string" column="NAME"/>
<one-to-one name="address" class="mypack.Address" cascade="all"/>
</class>
<class name="mypack.Address" table="ADDRESSES">
<id name="id" type="int" column="ADDRESS_ID">
<generator class="foreign">
<param name="property">address</param>
</generator>
</id>
<property name="city" type="string" column="CITY"/>
<property name="state" type="string" column="STATE"/>
<one-to-one name="person" class="mypack.Person" constrained="true"/>
</class>
Related
I have two classes A and B.
<id name="id" type="java.lang.Integer" column="A_ID">
<generator class="identity" />
</id>
<property name="name" column="NAME"/>
<many-to-one name="B" cascade="all"
column="B_ID" unique="true"/>
</class>
<id name="id" type="java.lang.Integer" column="B">
<generator class="identity" />
</id>
<property name="n" column="N"/>
</class>
A.setB(new B());
When I save it works fine.
when I remove the record. A.setB(null);
I see a orphan record.
I see in A Table the column for B is null but on B Table there is still a record.
I tried to look in other solutions but couldnot find the ans to this.
I'm adding ResourcePermission to the object Report. Each Query object can have in a one-to-one relationship. A Query extends Resource and has ResourcePermission's in a one-to-many (one Query to many Permissions).
I need to add the same property to the Report object associated with the Query because it can have different permissions. When I add the list and the map the one Query to many Permission relationship I get
Caused by: org.hibernate.MappingException: Repeated column in mapping for entity: com.bio.ResourcePermission column: resource_id (should be mapped with insert="false" update="false")
Which I am not understanding why, the Report does not extend Query or Resource and therefore it isn't mapped twice. Can a table just not be the many for multiple one-to-many relationships?
<class name="com.bio.Report" table="REPORT">
<id name="id" type="long" column="id">
<generator class="foreign">
<param name="property">query</param>
</generator>
</id>
<property name="name" column="name"/>
<!--Trying to add this list mapping breaks it-->
<bag name="permissions" table="RESOURCE_PERMISSION">
<key column="resource_id" not-null="true"/>
<one-to-many class="com.bio.ResourcePermission"/>
</bag>
<!-- This query extends Resource-->
<one-to-one name="query" class="com.bio.Query" />
</class>
This is the original item that had ResourcePermissions
<class name="com.bio.Resource" table="RESOURCE">
<id name="id" type="long" column="id">
<generator class="native">
<param name="sequence">SEQ_RESOURCE_AUTO</param>
</generator>
</id>
<bag name="permissions" table="RESOURCE_PERMISSION" lazy="true" batch-size="50" cascade="all-delete-orphan">
<key column="resource_id" not-null="true"/>
<one-to-many class="com.bio.ResourcePermission"/>
</bag>
</class>
The Permission mapping
<class name="com.bio.ResourcePermission" table="RESOURCE_PERMISSION">
<id name="id" type="long" column="id">
<generator class="native">
<param name="sequence">SEQ_RES_PERM_AUTO</param>
</generator>
</id>
<property name="canEdit" column="edit"/>
<property name="canView" column="can_view"/>
<property name="canRun" column="run"/>
<property name="everyone" column="everyone"/>
</class>
I had to set inverse="true" on the Report mapping since the ReportPermission will be responsible for the relationship.
<bag name="permissions" table="RESOURCE_PERMISSION" inverse="true">
<key column="resource_id" not-null="true"/>
<one-to-many class="com.bio.ResourcePermission"/>
</bag>
I'm using Java 1.6, Hibernate 3.1, MySQL 5.5, XML mapping. I have two tables, partner and partner_http_account. I'll just show you the relevant fields.
partner:
partnerid dec(22,0) [primary key]
partner_http_account:
partnerhttpacctid dec(22,0) [primary key]
partnerid dec(22,0) [foreign key]
Here's the XML mapping:
<class name="com.rc.model.partner.Partner" table="partner" mutable="true">
<id name="partnerId" type="int">
<column name="partnerid" scale="10" precision="0" not-null="true" unique="true" sql-type="int unsigned"/>
<generator class="com.rc.model.jdbc.sequence.MexpIdentifierGenerator">
<param name="sequence">seq_partnerid</param>
<param name="idDataType">int</param>
</generator>
</id>
...
<one-to-one name="partnerHTTPAccount" class="com.rc.model.partner.PartnerHTTPAccount" lazy="false"
foreign-key="partnerid" cascade="all"/>
</class>
<class name="com.rc.model.partner.PartnerHTTPAccount" table="partner_http_account">
<id name="partnerHttpAcctId" type="int">
<column name="partnerhttpacctid" scale="10" precision="0" not-null="true" unique="true" sql-type="int unsigned"/>
<generator class="com.rc.model.jdbc.sequence.MexpIdentifierGenerator">
<param name="sequence">seq_partnerhttpacctid</param>
<param name="idDataType">int</param>
</generator>
</id>
<many-to-one name="partner" class="com.rc.model.partner.Partner" column="partnerid"
foreign-key="partnerid" cascade="none"/>
</class>
Here is my Java code:
public List<Partner> getPartnersByDomainStartsWith(String domainStartsWith) {
Query hQuery = sessionManager.getSession().createQuery("from Partner p " +
"left outer join fetch p.partnerHTTPAccount " +
"where p.domain like :domainStartsWith||'%'");
hQuery.setString("domainStartsWith", domainStartsWith);
return hQuery.list();
}
And here is what Hibernate is generating:
select partner0_.partnerid as partnerid0_,
partnerhtt1_.partnerhttpacctid as partnerh1_1_,
...
partnerhtt1_.partnerid as partnerid104_1_,
...
from partner partner0_
left outer join partner_http_account partnerhtt1_ on partner0_.partnerid=partnerhtt1_.partnerhttpacctid
where partner0_.domain like concat(?, '%')
My problem is the generated sql query of these two tables is joining on the wrong field. It should join on partner0.partnerid=partnerhtt1.partnerid instead. Would really appreciate some insight. Thanks.
This is really well described in the Hibernate documentation:
<class name="Person">
<id name="id" column="personId">
<generator class="native"/>
</id>
<many-to-one name="address"
column="addressId"
unique="true"
not-null="true"/>
</class>
<class name="Address">
<id name="id" column="addressId">
<generator class="native"/>
</id>
<one-to-one name="person"
property-ref="address"/>
</class>
Notice how property-ref is used, to indicate that the one-to-one is the inverse side of the association mapped by the address property.
Could somebody explain me how to map a one-to-zero association with hibernate (using mapping xml files NOT annotations)?
These are the rules:
A Menu can have 0 or 1 Area associated.
An Area belongs to a Menu. (Or, if it is easier for you to modelize it: An Area can have 0 or 1 Menu associated).
Here are the desired TABLES (I want to use foreign keys):
TABLE MENU:
ID
NAME
FKID_AREA
TABLE AREA:
ID
NAME
FKID_MENU
Thanks!
You should remove the FKID_AREA from the MENU table, because it's not needed (and is even a problem, since it's redendant with AREA.FKID_MENU).
For the rest, this is described in the Hibernate documentation on bidirectional one-to-one association mappings:
<class name="Area">
<id name="id" column="ID">
<generator class="native"/>
</id>
<many-to-one name="menu"
column="FKID_MENU"
unique="true"
not-null="false"/>
</class>
<class name="Menu">
<id name="id" column="ID">
<generator class="native"/>
</id>
<one-to-one name="area"
property-ref="menu"/>
</class>
You should remove FKID_MENU from AREA table. As per your description, your hbm mapping would be below
<class name="Menu">
<id name="id" column="ID">
<generator class="native"/>
</id>
<property name="name" cloumn="name"/>
<many-to-one name="area" column="FKID_AREA" class="Area"/>
</class>
<class name="Area">
<id name="id" column="ID">
<generator class="native"/>
</id>
<property name="name" cloumn="name"/>
</class>
I have 2 tables, one table is
City Table ( int id, string name)
and my another table is
Distance table(int id,int cityId (FK city),int neighbourId(FK city))
I want to use Hibernate but I can't establish a relationship between these tables in Hibernate.
what about something like
<class name="City" table="CITIES">
<id name="id" type="integer">
<generator class="native" />
</id>
<property name="name" />
<set name="neighbours" table="DISTANCES">
<key column="city_id" />
<many-to-one name="neighbour" class="City" />
</set>
</class>
didn't test it though.
Ok, I can see any problem to do it normally.
<class name="City" table="CITY">
<id name="id" type="integer">
<generator class="native" />
</id>
<property name="name" />
</class>
<class name="Distance" table="DISTANCE">
<id name="id" type="integer">
<generator class="native" />
</id>
<many-to-one name="city" column="cityId" class="City"/>
<many-to-one name="neighbour" column="neighbourId" class="City"/>
</class>
didn't test it neither.