Calculated properties

Synopsis

Calculated properties allow you to add or remove properties to a variable or a family depending on the context.

Here is the list of editable properties:

Attribute applying to	Property’s name	Comment
Variable Family	hidden	Hides a variable or a family, in this case it is not accessible in read-write mode, but remains accessible in a calculation or in read-only mode. See also hidden access control.
Variable Family	disabled	Deactivates a variable or family, in this case it is never accessible. See also disabled access control.
Variable	frozen	A frozen variable is a variable that the operator cannot change the value.
Variable	mandatory	The variable expects a value other than null (or None in Python) or [] for multiple variables. See also for non multiple variables we call it a nullable variable.
Variable	empty	The multiple variable allow the value null (or None in Python) See also we call it a nullable variable.

A property can be calculated. In this case we have two possibilities:

• calculation via Jinja (see also the tutorial with a real world sample variable jinja)

• calculation via a variable (see also the tutorial with a real world sample variable calculation)

Parameters

Variable parameters

Parameter	Comment	Sample
type string	Calculation type. This parameter is optional. It is deduced from the presence of the parameter “variable” in a calculation.	variable
variable string mandatory	Name of the associated variable. It’s better to use relative path notation.	_.my_variable
when/when_not	Compare the value of the variable define in variable attribute. If the related variable is the boolean typed variable, the default value is true	See the tutorial with a real world sample when_not)
propertyerror boolean or transitive	If access to the variable is not possible due to a property (for example disabled) by default an error is returned. The overall coherence is not guaranteed. If the parameter is false, the calculated value is false in this condition. If the parameter is transitive, the calculated is true if the variable raise propertyerror or false otherwise. Default value: true	transitive false
optional boolean	The variable in calculation may not exist. This generates an error. Overall coherence is not guaranteed. To avoid this set the optional parameter to true. In this case, if variable in calculation is not exists, the variable is always accessible.	true
default boolean	If optional parameter is set to true and the variable in calculation is not exist, the variable is accessible. If you do not want this behavior, set this parameter to false.	false
description string	Rougail engine create a description like “when the variable “xxxx” has the value “yyyy”. You can personnalize here the calculation description

Jinja parameters

Parameter	Comment	Sample
type string	The calculation type. This parameter is optional. It is deduced from the presence of the parameter “jinja” in calculation.	jinja
jinja string mandatory	Jinja template. For a multiple variable, each line represents a value. It’s better to use relative path notation in Jinja template.	{% if _.my_variable %} {{ _.my_variable }} {% endif %}
params dict	Additional parameters passed to the Jinja template See below to have params possibility.	See the tutorial with a real world sample params)
return_type string	Jinja template could return two type of value: string (default): that means the Jinja template return an error message that explain why we don’t have access to this variable boolean: the Jinja template return “true” or “false”. The value true means that the properties is present.	See the tutorial with a real world sample return_type)
description string recommanded	Rougail engine cannot deduce what you want to do in Jinja template. You have to describe it for documentation purpose. If return_type parameter is boolean, this description is used in error message.	See the tutorial with a real world sample description)

In the case of a Jinja type calculation, it is possible to have parameters (params).

There are two types of parameter:

• the standard parameters (string, boolean, integer, null), in this case just do: “key: value”

• advanced settings:

  • parameter via a variable

  • parameter via information

  • parameter via an identifier: in the case of a variable in a dynamically built family

  • parameter via an index: in the case of a variable in a sequence

  • parameter via the current namespace

Parameters for variable type param

Parameter	Comments	Sample
type string	Parameter’s type	variable
variable string mandatory	Variable’s name It’s better to use relative path notation.	_.my_variable
propertyerror boolean	If access to the variable is not possible due to a property (for example disabled) by default an error is returned. If the parameter is false, the parameter is not passed to the Jinja template. Default value: true	false
optional boolean	The variable may not exist depending on YAML file imports. If the optional parameter is true, the parameter will simply be deleted if the variable does not exist. Default value: false	true
whole boolean	In sequence family, only the value of the variable in the current element is propose. This parameter allow you to have all values for all elements. Default value: false.	true

Parameters for information type param

Parameter	Comments	Sample
information string mandatory	Name of the information whose value we want to retrieve.	doc
variable string	Variable’s name. If not specified, the information is retrieve in Tiramisu Config. It’s better to use relative path notation.	_.my_variable