hibernate-orm/reference/en/modules/toolset_guide.xml

<chapter id="toolsetguide" revision="2">
    <title>Toolset Guide</title>

    <para>
        Roundtrip engineering with Hibernate is possible using a set of Eclipse plugins,
        commandline tools, as well as Ant tasks.
    </para>

    <para>
        The <emphasis>Hibernate Tools</emphasis> currently include plugins for the Eclipse
        IDE as well as Ant tasks for reverse engineering of existing databases:
    </para>

    <itemizedlist>
        <listitem><para>
            <emphasis>Mapping Editor:</emphasis> An editor for Hibernate XML mapping files,
            supporting auto-completion and syntax highlighting. It also supports semantic
            auto-completion for class names and property/field names, making it much more versatile than a normal XML editor.
        </para></listitem>
        <listitem><para>
            <emphasis>Console:</emphasis> The console is a new view in Eclipse. In addition to
            a tree overview of your console configurations, you also get an interactive view
            of your persistent classes and their relationships. The console allows you to
            execute HQL queries against your database and browse the result directly in
            Eclipse.
        </para></listitem>
        <listitem><para>
            <emphasis>Development Wizards:</emphasis> Several wizards are provided with the
            Hibernate Eclipse tools; you can use a wizard to quickly generate Hibernate configuration
            (cfg.xml) files, or you may even completely reverse engineer an existing database schema
            into POJO source files and Hibernate mapping files. The reverse engineering wizard
            supports customizable templates.
        </para></listitem>
        <listitem><para>
            <emphasis>Ant Tasks:</emphasis>
        </para></listitem>

    </itemizedlist>

    <para>
        Please refer to the <emphasis>Hibernate Tools</emphasis> package and it's documentation
        for more information.
    </para>

    <para>
        However, the Hibernate main package comes bundled with an integrated tool (it can even
        be used from "inside" Hibernate on-the-fly): <emphasis>SchemaExport</emphasis> aka
        <literal>hbm2ddl</literal>.
    </para>

    <sect1 id="toolsetguide-s1" revision="2">
        <title>Automatic schema generation</title>

        <para>
            DDL may be generated from your mapping files by a Hibernate utility. The generated
            schema includes referential integrity constraints (primary and foreign keys) for
            entity and collection tables. Tables and sequences are also created for mapped
            identifier generators.
        </para>
        
        <para>
            You <emphasis>must</emphasis> specify a SQL <literal>Dialect</literal> via the 
            <literal>hibernate.dialect</literal> property when using this tool, as DDL
            is highly vendor specific.
        </para>

        <para>
            First, customize your mapping files to improve the generated schema.
        </para>

        <sect2 id="toolsetguide-s1-2" revision="3">
            <title>Customizing the schema</title>

            <para>
                Many Hibernate mapping elements define optional attributes named <literal>length</literal>,
                <literal>precision</literal> and <literal>scale</literal>. You may set the length, precision 
                and scale of a column with this attribute. 
                
            </para>

            <programlisting><![CDATA[<property name="zip" length="5"/>]]></programlisting>
            <programlisting><![CDATA[<property name="balance" precision="12" scale="2"/>]]></programlisting>

            <para>
                Some tags also accept a <literal>not-null</literal> attribute (for generating a 
                <literal>NOT NULL</literal> constraint on table columns) and a <literal>unique</literal> 
                attribute (for generating <literal>UNIQUE</literal> constraint on table columns).
            </para>

            <programlisting><![CDATA[<many-to-one name="bar" column="barId" not-null="true"/>]]></programlisting>

            <programlisting><![CDATA[<element column="serialNumber" type="long" not-null="true" unique="true"/>]]></programlisting>

            <para>
                A <literal>unique-key</literal> attribute may be used to group columns in
                a single unique key constraint. Currently, the specified value of the 
                <literal>unique-key</literal> attribute is <emphasis>not</emphasis> used 
                to name the constraint in the generated DDL, only to group the columns in 
                the mapping file.
            </para>
            
            <programlisting><![CDATA[<many-to-one name="org" column="orgId" unique-key="OrgEmployeeId"/>
<property name="employeeId" unique-key="OrgEmployee"/>]]></programlisting>

            <para>
                An <literal>index</literal> attribute specifies the name of an index that
                will be created using the mapped column or columns. Multiple columns may be 
                grouped into the same index, simply by specifying the same index name. 
            </para>

            <programlisting><![CDATA[<property name="lastName" index="CustName"/>
<property name="firstName" index="CustName"/>]]></programlisting>

            <para>
                A <literal>foreign-key</literal> attribute may be used to override the name 
                of any generated foreign key constraint.
            </para>
            
            <programlisting><![CDATA[<many-to-one name="bar" column="barId" foreign-key="FKFooBar"/>]]></programlisting>

            <para>
                Many mapping elements also accept a child <literal>&lt;column&gt;</literal> element. 
                This is particularly useful for mapping multi-column types:
            </para>

            <programlisting><![CDATA[<property name="name" type="my.customtypes.Name"/>
    <column name="last" not-null="true" index="bar_idx" length="30"/>
    <column name="first" not-null="true" index="bar_idx" length="20"/>
    <column name="initial"/>
</property>]]></programlisting>

            <para>
                The <literal>default</literal> attribute lets you specify a default value for
                a column (you should assign the same value to the mapped property before
                saving a new instance of the mapped class).
            </para>

            <programlisting><![CDATA[<property name="credits" type="integer" insert="false">
    <column name="credits" default="10"/>
</property>]]></programlisting>

            <programlisting><![CDATA[<version name="version" type="integer" insert="false">
    <column name="version" default="0"/>
</property>]]></programlisting>

            <para>
                The <literal>sql-type</literal> attribute allows the user to override the default 
                mapping of a Hibernate type to SQL datatype.
            </para>
            
            <programlisting><![CDATA[<property name="balance" type="float">
    <column name="balance" sql-type="decimal(13,3)"/>
</property>]]></programlisting>
            
            <para>
                The <literal>check</literal> attribute allows you to specify a check constraint.
            </para>
            
            <programlisting><![CDATA[<property name="foo" type="integer">
    <column name="foo" check="foo > 10"/>
</property>]]></programlisting>

            <programlisting><![CDATA[<class name="Foo" table="foos" check="bar < 100.0">
    ...
    <property name="bar" type="float"/>
</class>]]></programlisting>
            

            <table frame="topbot" id="schemattributes-summary" revision="2">
                <title>Summary</title>
                <tgroup cols="3">
                    <colspec colwidth="1*"/>
                    <colspec colwidth="1*"/>
                    <colspec colwidth="2.5*"/>
                    <thead>
                        <row>
                            <entry>Attribute</entry>
                            <entry>Values</entry>
                            <entry>Interpretation</entry>
                        </row>
                    </thead>
                    <tbody>
                        <row>
                            <entry><literal>length</literal></entry>
                            <entry>number</entry>
                            <entry>column length</entry>
                        </row>
                        <row>
                            <entry><literal>precision</literal></entry>
                            <entry>number</entry>
                            <entry>column decimal precision</entry>
                        </row>
                        <row>
                            <entry><literal>scale</literal></entry>
                            <entry>number</entry>
                            <entry>column decimal scale</entry>
                        </row>
                        <row>
                            <entry><literal>not-null</literal></entry>
                            <entry><literal>true|false</literal></entry>
                            <entry>specfies that the column should be non-nullable</entry>
                        </row>
                        <row>
                            <entry><literal>unique</literal></entry>
                            <entry><literal>true|false</literal></entry>
                            <entry>specifies that the column should have a unique constraint</entry>
                        </row>
                        <row>
                            <entry><literal>index</literal></entry>
                            <entry><literal>index_name</literal></entry>
                            <entry>specifies the name of a (multi-column) index</entry>
                        </row>
                        <row>
                            <entry><literal>unique-key</literal></entry>
                            <entry><literal>unique_key_name</literal></entry>
                            <entry>specifies the name of a multi-column unique constraint</entry>
                        </row>
                        <row>
                            <entry><literal>foreign-key</literal></entry>
                            <entry><literal>foreign_key_name</literal></entry>
                            <entry>
                                specifies the name of the foreign key constraint generated
                                for an association, for a <literal>&lt;one-to-one&gt;</literal>, 
                                <literal>&lt;many-to-one&gt;</literal>, <literal>&lt;key&gt;</literal>, 
                                or <literal>&lt;many-to-many&gt;</literal> mapping element. Note that
                                <literal>inverse="true"</literal> sides will not be considered
                                by <literal>SchemaExport</literal>.
                            </entry>
                        </row>
                        <row>
                            <entry><literal>sql-type</literal></entry>
                            <entry><literal>SQL column type</literal></entry>
                            <entry>
                                overrides the default column type (attribute of 
                                <literal>&lt;column&gt;</literal> element only)
                            </entry>
                       </row>
                       <row>
                            <entry><literal>default</literal></entry>
                            <entry>SQL expression</entry>
                            <entry>
                                specify a default value for the column
                            </entry>
                       </row>
                       <row>
                            <entry><literal>check</literal></entry>
                            <entry>SQL expression</entry>
                            <entry>
                                create an SQL check constraint on either column or table
                            </entry>
                       </row>
                   </tbody>
                </tgroup>
            </table>
            
            <para>
                The <literal>&lt;comment&gt;</literal> element allows you to specify comments
                for the generated schema.
            </para>
            
            <programlisting><![CDATA[<class name="Customer" table="CurCust">
    <comment>Current customers only</comment>
    ...
</class>]]></programlisting>

            <programlisting><![CDATA[<property name="balance">
    <column name="bal">
        <comment>Balance in USD</comment>
    </column>
</property>]]></programlisting>
            
            <para>
                This results in a <literal>comment on table</literal> or 
                <literal>comment on column</literal> statement in the generated
                DDL (where supported).
            </para>

        </sect2>

        <sect2 id="toolsetguide-s1-3" revision="2">
            <title>Running the tool</title>

            <para>
                The <literal>SchemaExport</literal> tool writes a DDL script to standard out and/or
                executes the DDL statements.
            </para>

            <para>
                <literal>java -cp </literal><emphasis>hibernate_classpaths</emphasis>
                <literal>org.hibernate.tool.hbm2ddl.SchemaExport</literal> <emphasis>options mapping_files</emphasis>
            </para>

            <table frame="topbot">
                <title><literal>SchemaExport</literal> Command Line Options</title>
                <tgroup cols="2">
                    <colspec colwidth="1.5*"/>
                    <colspec colwidth="2*"/>
                    <thead>
                        <row>
                            <entry>Option</entry>
                            <entry>Description</entry>
                        </row>
                    </thead>
                    <tbody>
                        <row>
                            <entry><literal>--quiet</literal></entry>
                            <entry>don't output the script to stdout</entry>
                        </row>
                        <row>
                            <entry><literal>--drop</literal></entry>
                            <entry>only drop the tables</entry>
                        </row>
                        <row>
                            <entry><literal>--create</literal></entry>
                            <entry>only create the tables</entry>
                        </row>
                        <row>
                            <entry><literal>--text</literal></entry>
                            <entry>don't export to the database</entry>
                        </row>
                        <row>
                            <entry><literal>--output=my_schema.ddl</literal></entry>
                            <entry>output the ddl script to a file</entry>
                        </row>
                        <row>
                            <entry><literal>--naming=eg.MyNamingStrategy</literal></entry>
                            <entry>select a <literal>NamingStrategy</literal></entry>
                        </row>
                         <row>
                            <entry><literal>--config=hibernate.cfg.xml</literal></entry>
                            <entry>read Hibernate configuration from an XML file</entry>
                        </row>
                        <row>
                            <entry><literal>--properties=hibernate.properties</literal></entry>
                            <entry>read database properties from a file</entry>
                        </row>
                        <row>
                            <entry><literal>--format</literal></entry>
                            <entry>format the generated SQL nicely in the script</entry>
                        </row>
                        <row>
                            <entry><literal>--delimiter=;</literal></entry>
                            <entry>set an end of line delimiter for the script</entry>
                        </row>
                    </tbody>
                </tgroup>
            </table>

            <para>
                You may even embed <literal>SchemaExport</literal> in your application:
            </para>

            <programlisting><![CDATA[Configuration cfg = ....;
new SchemaExport(cfg).create(false, true);]]></programlisting>

        </sect2>

        <sect2 id="toolsetguide-s1-4">
            <title>Properties</title>

            <para>
                Database properties may be specified
            </para>

            <itemizedlist spacing="compact">
                <listitem>
                    <para>as system properties with <literal>-D</literal><emphasis>&lt;property&gt;</emphasis></para>
                </listitem>
                <listitem>
                    <para>in <literal>hibernate.properties</literal></para>
                </listitem>
                <listitem>
                    <para>in a named properties file with <literal>--properties</literal></para>
                </listitem>
            </itemizedlist>

            <para>
                The needed properties are:
            </para>

            <table frame="topbot">
                <title>SchemaExport Connection Properties</title>
                <tgroup cols="2">
                    <colspec colwidth="1.5*"/>
                    <colspec colwidth="2*"/>
                    <thead>
                        <row>
                            <entry>Property Name</entry>
                            <entry>Description</entry>
                        </row>
                    </thead>
                    <tbody>
                    <row>
                        <entry><literal>hibernate.connection.driver_class</literal></entry>
                        <entry>jdbc driver class</entry>
                    </row>
                    <row>
                        <entry><literal>hibernate.connection.url</literal></entry>
                        <entry>jdbc url</entry>
                    </row>
                    <row>
                        <entry><literal>hibernate.connection.username</literal></entry>
                        <entry>database user</entry>
                    </row>
                    <row>
                        <entry><literal>hibernate.connection.password</literal></entry>
                        <entry>user password</entry>
                    </row>
                    <row>
                        <entry><literal>hibernate.dialect</literal></entry>
                        <entry>dialect</entry>
                    </row>
                    </tbody>
                </tgroup>
            </table>

        </sect2>

        <sect2 id="toolsetguide-s1-5">
            <title>Using Ant</title>

            <para>
                You can call <literal>SchemaExport</literal> from your Ant build script:
            </para>

            <programlisting><![CDATA[<target name="schemaexport">
    <taskdef name="schemaexport"
        classname="org.hibernate.tool.hbm2ddl.SchemaExportTask"
        classpathref="class.path"/>
    
    <schemaexport
        properties="hibernate.properties"
        quiet="no"
        text="no"
        drop="no"
        delimiter=";"
        output="schema-export.sql">
        <fileset dir="src">
            <include name="**/*.hbm.xml"/>
        </fileset>
    </schemaexport>
</target>]]></programlisting>

        </sect2>

        <sect2 id="toolsetguide-s1-6" revision="2">
            <title>Incremental schema updates</title>

            <para>
                The <literal>SchemaUpdate</literal> tool will update an existing schema with "incremental" changes.
                Note that <literal>SchemaUpdate</literal> depends heavily upon the JDBC metadata API, so it will
                not work with all JDBC drivers.
            </para>

            <para>
                <literal>java -cp </literal><emphasis>hibernate_classpaths</emphasis>
                <literal>org.hibernate.tool.hbm2ddl.SchemaUpdate</literal> <emphasis>options mapping_files</emphasis>
            </para>

            <table frame="topbot">
                <title><literal>SchemaUpdate</literal> Command Line Options</title>
                <tgroup cols="2">
                    <colspec colwidth="1.5*"/>
                    <colspec colwidth="2*"/>
                    <thead>
                        <row>
                            <entry>Option</entry>
                            <entry>Description</entry>
                        </row>
                    </thead>
                    <tbody>
                        <row>
                            <entry><literal>--quiet</literal></entry>
                            <entry>don't output the script to stdout</entry>
                        </row>
                        <row>
                            <entry><literal>--text</literal></entry>
                            <entry>don't export the script to the database</entry>
                        </row>
                        <row>
                            <entry><literal>--naming=eg.MyNamingStrategy</literal></entry>
                            <entry>select a <literal>NamingStrategy</literal></entry>
                        </row>
                        <row>
                            <entry><literal>--properties=hibernate.properties</literal></entry>
                            <entry>read database properties from a file</entry>
                        </row>
                        <row>
                            <entry><literal>--config=hibernate.cfg.xml</literal></entry>
                            <entry>specify a <literal>.cfg.xml</literal> file</entry>
                        </row>
                     </tbody>
                </tgroup>
            </table>

            <para>
                You may embed <literal>SchemaUpdate</literal> in your application:
            </para>

            <programlisting><![CDATA[Configuration cfg = ....;
new SchemaUpdate(cfg).execute(false);]]></programlisting>

        </sect2>

        <sect2 id="toolsetguide-s1-7">
            <title>Using Ant for incremental schema updates</title>

            <para>
                You can call <literal>SchemaUpdate</literal> from the Ant script:
            </para>

            <programlisting><![CDATA[<target name="schemaupdate">
    <taskdef name="schemaupdate"
        classname="org.hibernate.tool.hbm2ddl.SchemaUpdateTask"
        classpathref="class.path"/>
    
    <schemaupdate
        properties="hibernate.properties"
        quiet="no">
        <fileset dir="src">
            <include name="**/*.hbm.xml"/>
        </fileset>
    </schemaupdate>
</target>]]></programlisting>

        </sect2>

        <sect2 id="toolsetguide-s1-8" revision="1">
            <title>Schema validation</title>

            <para>
                The <literal>SchemaValidator</literal> tool will validate that the existing database schema "matches"
                your mapping documents. Note that <literal>SchemaValidator</literal> depends heavily upon the JDBC 
                metadata API, so it will not work with all JDBC drivers. This tool is extremely useful for testing.
            </para>

            <para>
                <literal>java -cp </literal><emphasis>hibernate_classpaths</emphasis>
                <literal>org.hibernate.tool.hbm2ddl.SchemaValidator</literal> <emphasis>options mapping_files</emphasis>
            </para>

            <table frame="topbot">
                <title><literal>SchemaValidator</literal> Command Line Options</title>
                <tgroup cols="2">
                    <colspec colwidth="1.5*"/>
                    <colspec colwidth="2*"/>
                    <thead>
                        <row>
                            <entry>Option</entry>
                            <entry>Description</entry>
                        </row>
                    </thead>
                    <tbody>
                        <row>
                            <entry><literal>--naming=eg.MyNamingStrategy</literal></entry>
                            <entry>select a <literal>NamingStrategy</literal></entry>
                        </row>
                        <row>
                            <entry><literal>--properties=hibernate.properties</literal></entry>
                            <entry>read database properties from a file</entry>
                        </row>
                        <row>
                            <entry><literal>--config=hibernate.cfg.xml</literal></entry>
                            <entry>specify a <literal>.cfg.xml</literal> file</entry>
                        </row>
                     </tbody>
                </tgroup>
            </table>

            <para>
                You may embed <literal>SchemaValidator</literal> in your application:
            </para>

            <programlisting><![CDATA[Configuration cfg = ....;
new SchemaValidator(cfg).validate();]]></programlisting>

        </sect2>

        <sect2 id="toolsetguide-s1-9">
            <title>Using Ant for schema validation</title>

            <para>
                You can call <literal>SchemaValidator</literal> from the Ant script:
            </para>

            <programlisting><![CDATA[<target name="schemavalidate">
    <taskdef name="schemavalidator"
        classname="org.hibernate.tool.hbm2ddl.SchemaValidatorTask"
        classpathref="class.path"/>
    
    <schemavalidator
        properties="hibernate.properties">
        <fileset dir="src">
            <include name="**/*.hbm.xml"/>
        </fileset>
    </schemaupdate>
</target>]]></programlisting>

        </sect2>

    </sect1>

</chapter>