The table element is perhaps the most complex element. It contains the majority of the information needed by DbForms to render the DbForms JSP tags. A table element is needed for for each table to be used with DbForms.

A starting set of table elements as well as a basic dbconnection element can be generated using the DevGui tool. This tool, which is described in Chapter 5, DevGui , verifies database connectivity and then uses JDBC capabilities to query the metadata for tables in the database. This can be a signficant time-saving step.

The nesting and ordering of subelements within each table tag is shown below.

   <table>
     <field/>
     <calc/>
     <foreign-key/>
     <events>
       <event/>
     </events>
     <interceptor>
       <param/>
     </interceptor>
     <granted-privileges/>
   </table>

The top level subelements, field through granted-privileges may each occur zero or more times except events which is optional but may appear a maximum of one time.

There is no element content in the any of the elements. All information is supplied in the attributes of these elements and the attributes of their subelements.

The table element itself has one required attribute, name, giving the name of the table and a number of optional attributes. All of the attributes are listed below.

The field element describes a column in the table. There are two required attributes, name, giving the name of the column in the table, and fieldType, giving the data type of the column. There are also many optional attributes. All of the attributes are listed below.

The calc element is similar to the field element except that the encoding attribute is not allowed. A field defined within a calc element is not populated by the user. Rather, the value is generated by an interceptor.

Columns in a table that are foreign keys in the SQL sense should be described in using the element foreign-key rather than the field element. This allows DbForms to handle the field differently. There are limitations, however, on DbForms foreign key handling. See Chapter 19, Foreign Key support within DbForms for more details.

Every table uses, by default, the standard event configuration established in the events subelement nested directly within the root dbforms-config element. A developer can choose, however, to override the event class associated with a certain type of event, by adding and configuring the events element within a table element.

The events element itself is merely a container for one or more event subelements within it. Element events has no attributes. Each event element may have a number of attributes and may enclose nested param subelements. See Chapter 22, Pluggable events and especially Section 22.5, “Override the event classes on a table-by-table basis ” for more details.

The interceptor element is used for declaring interceptor classes locally for a particular table. See the discussion later in this chapter on the interceptor element for details of the attributes and the param subelement. As mentioned in Chapter 15, Application hook-ups (Interceptors) , it is also possible to declare interceptors globally to apply to all tables. Globally declared iterceptors are invoked for all tables but interceptors declared for specific tables are invoked only for that table. If both table-specific and global interceptors are defined, the table-specific iterceptor is invoked first and, if it signals success, the global interceptor is then invoked.

By default, all users of the DbForms application have full access to read and write all of the tables defined in dbforms-config.xml.The granted-privileges element has four optional attributes that can establish limits for specific user roles. The attributes are select, insert, update, and delete. User roles are those defined in the application web.xml file. See Chapter 9, Security for more details.