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Each data object (DO) represents a record in the database, that means that for every table in the database, there is a data object class. CRM.COM software uses Hibernate, a data persistence framework used to retrieve and persist data to the database. What does this section cover?
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In the following example, we will create and map a data object class for the table BANKBRANCHES.
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To create your database tables, you can follow this how-to guide.
Creating the Data Object Classes
All data objects should be placed under com.crm.dataobject.* named packages, extend either com.crm.dataobject.CRMDO or one of its subclasses and follow this naming convention: CRMDO<classname>CRMDO<entityname>.java.
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For each database field, a java property is defined. In some cases, transient fields might also exist. All the properties must be defined as private variables, and for each property, two accessor methods should be created: a getter and a setter method. In the setter methods of the persistent fields, setChange method (implemented in com.crm.dataobject.CRMDO) must be called in order to mark the specific field as modified and track its changes.
Note that id, name, altCode, description, createdByUser, updatedByUser, createdByUnit, updatedByUnit, createdDate, updatedDate, isDeleted and recVersion properties are defined in inherited from com.crm.dataobject.CRMDO CRMDO super class.
Mapping the Data Object Classes
Hibernate is used by CRM.COM to map a defined class to a database table and its properties to the table's fields.
Creating Hibernate Mapping Files
Hibernate Mapping files should always have the following format: <classname>.hbm.xml
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<?xml version="1.0"?> <!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN" "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd" > <hibernate-mapping default-access="field"> <class lazy="true" name="com.crm.dataobject.accounts.CRMDOBankBranch" table="BANKBRANCHES" > <meta attribute="class-description" inherit="false"> @hibernate.class table="BANKBRANCHES" </meta> <meta attribute="extends" inherit="false">com.crm.dataobject.CRMDO</meta> <cache usage="read-write" /> <id access="property" name="id" type="java.lang.String" column="BANKBRANCHID" > <meta attribute="field-description"> @hibernate.id generator-class="assigned" type="java.lang.String" column="BANKBRANCHID" </meta> <generator class="assigned" /> </id> <version name="recVersion" type="java.lang.Integer" column="RECVERSION" access="property" unsaved-value="undefined" > <meta attribute="field-description"> @hibernate.property column="RECVERSION" length="10" </meta> </version> <many-to-one name="createdByUser" class="com.crm.dataobject.users.CRMDOUser" not-null="true" > <meta attribute="field-description"> @hibernate.many-to-one not-null="true" @hibernate.column name="BANKBRANCHCREATEDBYUSERID" </meta> <column name="BANKBRANCHCREATEDBYUSERID" /> </many-to-one> <many-to-one name="updatedByUser" class="com.crm.dataobject.users.CRMDOUser" not-null="true" > <meta attribute="field-description"> @hibernate.many-to-one not-null="true" @hibernate.column name="BANKBRANCHUPDATEDBYUSERID" </meta> <column name="BANKBRANCHUPDATEDBYUSERID" /> </many-to-one> <many-to-one name="createdByUnit" class="com.crm.dataobject.networkmanagement.CRMDOUnit" not-null="true" > <meta attribute="field-description"> @hibernate.many-to-one not-null="true" @hibernate.column name="BANKBRANCHCREATEDBYOUUID" </meta> <column name="BANKBRANCHCREATEDBYOUUID" /> </many-to-one> <many-to-one name="updatedByUnit" class="com.crm.dataobject.networkmanagement.CRMDOUnit" not-null="true" > <meta attribute="field-description"> @hibernate.many-to-one not-null="true" @hibernate.column name="BANKBRANCHUPDATEDBYOUUID" </meta> <column name="BANKBRANCHUPDATEDBYOUUID" /> </many-to-one> <property name="createdDate" type="java.sql.Timestamp" column="BANKBRANCHCREATEDDATE" length="23" > <meta attribute="field-description"> @hibernate.property column="BANKBRANCHCREATEDDATE" length="23" </meta> </property> <property name="updatedDate" type="java.sql.Timestamp" column="BANKBRANCHUPDATEDDATE" length="23" > <meta attribute="field-description"> @hibernate.property column="BANKBRANCHUPDATEDDATE" length="23" </meta> </property> <property name="isDeleted" type="java.lang.Integer" column="BANKBRANCHDELETED" length="10" > <meta attribute="field-description"> @hibernate.property column="BANKBRANCHDELETED" length="10" </meta> </property> <many-to-one name="bank" class="com.crm.dataobject.accounts.CRMDOBank" not-null="true" > <meta attribute="field-description"> @hibernate.many-to-one not-null="true" @hibernate.column name="BANKID" </meta> <column name="BANKID" /> </many-to-one> <property name="name" type="java.lang.String" column="BANKBRANCHNAME" length="256" > <meta attribute="field-description"> @hibernate.property column="BANKBRANCHNAME" length="256" </meta> </property> <property name="altCode" type="java.lang.String" column="BANKBRANCHALTCODE" length="32" > <meta attribute="field-description"> @hibernate.property column="BANKBRANCHALTCODE" length="32" </meta> </property> <property name="description" type="java.lang.String" column="BANKBRANCHDESC" length="32512" > <meta attribute="field-description"> @hibernate.property column="BANKBRANCHDESC" length="32512" </meta> </property> <set name="paymentPreferences" lazy="true" inverse="true" cascade="none" > <meta attribute="field-description"> @hibernate.set lazy="true" inverse="true" cascade="none" @hibernate.collection-key column="BANKBRANCHID" @hibernate.collection-one-to-many class="com.crm.dataobject.accounts.CRMDOPaymentPreference" </meta> <key><column name="BANKBRANCHID" /></key> <one-to-many class="com.crm.dataobject.accounts.CRMDOPaymentPreference" /> </set> </class> </hibernate-mapping> |
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To map a variable, the <property> element is used.
- The name attribute is used to specify the property name.
- The column attribute is used to specify the table column the property is mapped on.
- The type attribute is used to specify the variable type.
- The length attribute is used to specify the length of the specific table column.
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In case we have a many-to-one relation with another table, the <many-to-one> element is used.
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<id> and <version> elements are used to map the primary key and the version properties of the java class. Through the version property, Hibernate can provide optimistic locking.
Hibernate Configuration File
Hibernate Configuration file (hibernate.cfg.xml) is used for defining all the hibernate mapping files. During the application's initialization process, hibernate reads this configuration file and maps the classes defined, to the database tables.
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<hibernate-configuration> <session-factory> ... <mapping resource="com/crm/dataobject/accounts/CRMDOBankBranch.hbm.xml" /> ... </session-factory> </hibernate-configuration> |
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To continue implementing the model layer, go to Developing the Business Objects