$, $val, $value
===============

The current object is a value set. $ will access to a variable value within this value set.

Note that when joining several tables in a view and when the named variable is present in more than one of these tables, the value returned is a value sequence. Values of this sequence appear in the order of the tables defined in the view. For more details see also the presentation about `multilines <http://slides.com/yannickmarcon/opal-multilines>`_ support. If the values of the sequence are known to be identical (because the same data is repeated in several tables), it is possible to use the :doc:`../sequence/firstNotNull` method to reduce the sequence to one value.

Note also that if a script returns a value sequence and if the derived variable is not "repeatable", the value sequence is automatically reduced with the :doc:`../sequence/firstNotNull` strategy.

See also :doc:`group`, :doc:`id`, :doc:`join`, :doc:`this`, :doc:`variable`.

Syntax
------

.. code-block:: javascript

  $(name)
  // alternate syntax
  $val(name)
  $value(name)

.. list-table::
   :header-rows: 1
   :widths: 10 90

   * - Parameter
     - Description
   * - ``name``
     - | The name of the variable from which the value shall be retrieved. If the name is fully qualified, ie. "<datasource>.<table>:<variable>", the lookup will be first done in
       | view's reference tables and if not found will be looked up out of the view's scope.

Examples
--------

Returns the value for current value set and the named variable DO_YOU_SMOKE.

.. code-block:: javascript

  $('DO_YOU_SMOKE')

Returns the value for the current entity from the fully qualified table.

.. code-block:: javascript

  $('project.table:SMOKING')

When using a fully qualifying the variable, if the variable is not a variable from the tables referred by the view, the performance could be very poor as it would result in one request on an individual value in the database.