Release Notes <b-frame/> 0.1.3

1. Join Tables to List and Display Groups
2. Customizing Queries
3. Bug Fixes
4. Documentation

1. Join Tables to List and Display Groups

With this release it is possible to join tables to groups of type list and display, respectively. Using a join makes it is possible to display information not only from the table corresponding to a particular task but also from related tables. As an example consider the following Student Task.

<bf-app:task table="student">
  <bf-app:task name="course_list" table="visit">
    <bf-app:group type="list">
      <bf-app:field name="institute_name" label="Institute"/>
      <bf-app:field table="professor" name="id" alias="professor_test_id" label=""/>
      <bf-app:field table="professor" name="name" label="Professor"/>
      <bf-app:field table="course" name="id" alias="course_test_id" label=""/>
      <bf-app:field table="course" name="title" label="Course" link="true"/>
      <bf-app:join table="course" on="visit_ref_course">
        <bf-app:join table="professor" on="course_ref_prof"/>
      </bf-app:join>
    </bf-app:group>
  </bf-app:task>
</bf-app:task>

The tables course and professor are joined to the visit table for displaying the course's title and the professor's name. Note that the fields course.id and professor.id is given an alias because each field of a group needs a unique identifier. When thinking about identifiers, have in mind that each group is extended by <b-frame/> to include all primary key attributes (but only the defined attributes occur on a mask).

2. Customizing Queries

By default, the query of a top level task allows user input for the primary key fields. With this release it is possible to define these fields by using the <bf-app:query> and <bf-app:infix> tags.

<bf-app:task table="student">
  <bf-app:query>
    <bf-app:infix name="and">
      <bf-app:field name="id" label="ID"/>
      <bf-app:field name="name" label="Name"/>
    </bf-app:infix>
  </bf-app:query>
</bf-app:task>

The <bf-app:infix>'s name attribute defines the operator, e.g. and or or. <bf-app:infix> tags may be nested.

Note that currently it is not possible to include fields from other, joined tables into the condition of the query, this will become available in the future.

3. Bug Fixes

1. The Hsqldb data base doesn't seem to support the FOR UPDATE clause which is used by <b-frame/> to implement optimistic locking. In effect it was impossible to perform an update on Hsqldb. The new release configures the FOR UPDATE clause using the environment:
   • MySQL: FOR UPDATE,
   • Oracle: FOR UPDATE NOWAIT, and
   • Hsqldb: empty.
   Note that in case of using Hsqldb <b-frame/>'s optimistic lock is not completely multi user save because the record is not locked between reading and updating.
2. Prior <b-frame/> versions where using the parameters task, action, and state for coding state information into HTML links. On the other hand, database attributes where also coded into links and forms, hence it was impossible to have database attributes task, action, or state. To avoid this collision the new release introduced prefixes for keys in links:
   • ctrl  for the control parameters task, action, and state,
   • data  for data, and
   • original  for the backup copy of the data used to implement optimistic locking.

The tutorial at http://www.b-frame.org/applications.pdf has been updated.