Zero, Unset, Boolean, Drop, Null and Exists Functions
-----------------------------------------------------


.. index:: Macro function;fn.zero
.. index:: Macro function;fn.unset
.. index:: Macro function;fn.true
.. index:: Macro function;fn.false



+----------------+----------------------------+---------------------------------+--------------------+
| Function       | Description                |  Example                        | Output or Result   |
+================+============================+=================================+====================+
|                |                            | ::                              | ::                 |
|                |                            |                                 |                    |
| fn.zero        | Return a zero value.       |    {{fn.zero}}                  |    0               |
+----------------+----------------------------+---------------------------------+--------------------+
|                |                            | ::                              | ::                 |
|                |                            |                                 |                    |
| fn.unset       | Return an empty string.    |    {{fn.unset}}                 |    ''              |
+----------------+----------------------------+---------------------------------+--------------------+
|                |                            | ::                              | ::                 |
|                |                            |                                 |                    |
| fn.true        | Return a boolean True.     |    {{fn.true}}                  |    true            |
+----------------+----------------------------+---------------------------------+--------------------+
|                |                            | ::                              | ::                 |
|                |                            |                                 |                    |
| fn.false       | Return a boolean False.    |    {{fn.false}}                 |    false           |
+----------------+----------------------------+---------------------------------+--------------------+


Given input context:

1. ``{"input": {"field1": {"key1": "value1"}}}``
2. ``{"input": {"field1": None}}``
3. ``{"input": {"field1": ""}}``



.. index:: Macro function;fn.is_none_or_empty

+---------------------+-------------------------------------------------------------+--------------------------+------------------+
| Function            | Description                                                 |  Example                 | Input and Result |
+=====================+=============================================================+==========================+==================+
| fn.is_none_or_empty | Return a boolean if the argument is None or an empty string | ::                       | input 1.         |
|                     |                                                             |                          |                  |
|                     |                                                             |                          | ::               |
|                     |                                                             |    {{fn.is_none_or_empty |                  |
|                     |                                                             |       input.field1}}     |    false         |
|                     |                                                             |                          |                  |
|                     |                                                             |                          | input 2.         |
|                     |                                                             |                          |                  |
|                     |                                                             |                          | ::               |
|                     |                                                             |                          |                  |
|                     |                                                             |                          |    true          |
|                     |                                                             |                          |                  |
|                     |                                                             |                          | input 3.         |
|                     |                                                             |                          |                  |
|                     |                                                             |                          | ::               |
|                     |                                                             |                          |                  |
|                     |                                                             |                          |    true          |
|                     |                                                             |                          |                  |
+---------------------+-------------------------------------------------------------+--------------------------+------------------+


Given input context:

::

   {
    "input": {
      "test": null
    }
   }


.. index:: Macro function;fn.null

+----------------+----------------------------+---------------------------------+--------------------+
| Function       | Description                |  Example                        | Output or Result   |
+================+============================+=================================+====================+
| fn.null        | Returns Null. Useful in    |  ::                             | ::                 |
|                | comparison tests.          |                                 |                    |
|                |                            |     (( input.test ==            |    true            |
|                |                            |        fn.null ))               |                    |
|                |                            |                                 |                    |
+----------------+----------------------------+---------------------------------+--------------------+

.. index:: Macro function;fn.drop
.. index:: Macro function;fn.force_null

Useful in Configuration Templates:

+----------------+----------------------------+----------------------------------+--------------------+
| Function       | Description                |  Example                         | Output or Result   |
+================+============================+==================================+====================+
|                |                            | ::                               |                    |
|                |                            |                                  |                    |
| fn.drop        | Removes the attribute      |    {'name':                      | Attribute dropped  |
|                |                            |     '{{fn.drop}}'}               |                    |
|                |                            |                                  |                    |
+----------------+----------------------------+----------------------------------+--------------------+
|                |                            | ::                               | ::                 |
|                |                            |                                  |                    |
| fn.force_null  | Attribute has Null value   |    {'name':                      |    {'name': None}  |
|                |                            |   '{{fn.force_null}}'}           |                    |
|                |                            |                                  |                    |
+----------------+----------------------------+----------------------------------+--------------------+


Example of ``fn.drop`` in an if-then-else test from a Configuration Template of a workflow.
the attribute is dropped if not entered as input:

::
  
   "ldapDirectoryName": "(( input.cucm_user_ldapDirectoryName != '' )) 
     <{{ input.cucm_user_ldapDirectoryName }}> 
     <{{ fn.drop }}"


.. index:: Macro function;fn.exists


Given input context:

1. ``{"input": {"field1": {"key1": "value1"}}}``
2. ``{"input": {"field1": {"key1": null}}}``
3. ``{"input": {"field1": ""}}``


+-----------+---------------------------------------+----------------------------+------------------+
| Function  | Description                           |  Example                   | Input and Result |
+===========+=======================================+============================+==================+
| fn.exists | Return a boolean true if the argument | ::                         | input 1.         |
|           | is exits and has a non-null value.    |                            |                  |
|           |                                       |                            | ::               |
|           |                                       |    {{ fn.exists            |                  |
|           |                                       |       input.field1.key1 }} |    true          |
|           |                                       |                            |                  |
|           |                                       |                            | input 2.         |
|           |                                       |                            |                  |
|           |                                       |                            | ::               |
|           |                                       |                            |                  |
|           |                                       |                            |    false         |
|           |                                       |                            |                  |
|           |                                       |                            | input 3.         |
|           |                                       |                            |                  |
|           |                                       |                            | ::               |
|           |                                       |                            |                  |
|           |                                       |                            |    false         |
|           |                                       |                            |                  |
+-----------+---------------------------------------+----------------------------+------------------+
|           |                                       |                            | input 1, 2, 3    |
|           |                                       |                            |                  |
| fn.exists | If the *argument does not exist*, it  | ::                         | ::               |
|           | is interpreted as a string  - which   |                            |                  |
|           | is interpretable, so the function     |    {{ fn.exists            |    true          |
|           | returns true.                         |       field.key }}         |                  |
|           |                                       |                            |                  |
+-----------+---------------------------------------+----------------------------+------------------+




.. |VOSS-4-UC| replace:: VOSS-4-UC
.. |Unified CM| replace:: Unified CM