Calculated default values

Synopsis

A value can be calculated. In this case we have four possibilities:

calculation via Jinja template
calculation via a variable
calculation via an information
calculation via a identifier: in a dynamically built family returns the current identifier
calculation via an index: in the case of a follower variable returns the current index
calculation via the current namespace name

If the user modifies the value of the variable, the default value is no longer used, so the calculation is no longer carried out. This is also the case if the variable has the auto_save attribute.

On the other hand, if the variable is hidden (with the hidden parameter), it is the default value that is used and not the value customized by the user.

Note

A follower variable cannot be calculated automatically.

Parameters

Jinja template

Calculation type	Comment
type `string`	The value is `jinja`
jinja `string` `mandatory`	Please set a Jinja template.
params `dict`	Additional parameters passed to the Jinja template (see below).
description `string`	Additional information for the documentation and the error message in case of return_type is a boolean.

Variable

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
propertyerror `boolean`	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. Default value: `true`	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 “depends on a calculation”. You can personnalize here the calculation description

Information

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

Params

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

There are two types of params:

the standard parameters (string, boolean, integer, float or null), in this case just do: “key: value”
advanced settings (with something like “key: {}”:
- parameter via a variable
- parameter via an information
- parameter via an identifier: in a dynamically built family returns the current identifier
- parameter via an index: in the case of a follower variable returns the current index
- parameter via the current namespace name

Variable params

Parameter	Comments	Sample
type `string`	Type of parameter, which is variable.	variable
variable `string` `mandatory`	Variable’s path.	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 attribute is `false`, the parameter is not passed to the Jinja template. Default value: `false`	`true`
optional `boolean`	If the variable is not defined the value is always `null`. Default value: `false`	`true`
whole `boolean`	In dynamically built family only the value of the current index is retrieve. If this parameter is set to `true` it returns all If this parameter is set to `true`, it returns the set of values for all indices. Default value: `false`	`true`

Information params

Parameter

Comments

Sample

type

string

Type of parameter, which is information

information

information

string

mandatory

Name of the information whose value we want to retrieve.

doc

variable

string

By default, the information is a context information. It is possible to get a variable information. In this case just specify a path.

my_variable

Sample

Calculation via a Jinja template

Let’s start with an example from a simple Jinja template:

%YAML 1.2
---
version: 1.1

my_calculated_variable:
  default:
    jinja: 'no'
...

Here is a second example with a boolean variable:

%YAML 1.2
---
version: 1.1

my_calculated_variable:
  type: boolean
  default:
    jinja: 'false'
...

And a multiple value of the integer type:

%YAML 1.2
---
version: 1.1

my_calculated_variable:
  type: integer
  multi: true
  default:
    jinja: |
      1
      2
      3
...

Let’s create a variable whose value is returned by a python function:

%YAML 1.2
---
version: 1.1

my_calculated_variable:
  default:
    jinja: '{{ return_no() }}'
...

Then let’s create the return_no function:

def return_no():
    return 'no'

An example with parameters:

%YAML 1.2
---
version: 1.1

my_calculated_variable:
  description: my description
  default:
    jinja: |
            {{ param1 }}{% if param2 is defined %}_{{ param2 }}{% endif %}_{{ param3 }}
    params:
      param1: value
      param2:
        type: variable
        variable: _.unknown_variable
        optional: true
      param3:
        type: information
        information: doc
        variable: _.my_calculated_variable
...

An example with a identifier type parameter:

%YAML 1.2
---
version: 1.1

my_dyn_family_{{ identifier }}:
  dynamic:
    - val1
    - val2
  description: 'Describe {{ identifier }}'

  my_dyn_var:
    default:
      jinja: 'the identifier is: {{ param1 }}'
      params:
        param1:
          type: identifier

In this example, we see a dynamically built family. Two families will be created: my_dyn_family_val1.my_dyn_var and my_dyn_family_val2.my_dyn_var.

The value of the variable inside this family ‘this identifier is: ‘ + the value of the identifier (val1 and val2 respectively).

An example with an index type parameter:

%YAML 1.2
---
version: 1.1

family:
  type: sequence

  leader:
    - val1
    - val2

  follower1:
    default:
      type: jinja
      jinja: 'the index is: {{ param1 }}'
      params:
        param1:
          type: index
...

Calculation via a variable

Copy a variable in another:

%YAML 1.2
---
version: 1.1

my_variable:
  default:
    - val1
    - val2

my_calculated_variable:
  default:
    type: variable
    variable: _.my_variable
...

Copy the default value from a variable, means copy type, params and multi attribute too if not define in second variable.

%YAML 1.2
---
version: 1.1

my_variable:
  multi: true
  type: domainname
  params:
    allow_ip: true

my_calculated_variable:
  default:
    type: variable
    variable: _.var1

Here my_calculated_variable is a domainname variable with parameter allow_ip=True and multi to true.

Copy one variable to another if the source has no property problem:

%YAML 1.2
---
version: 1.1

my_variable:
  default: val1
  disabled: true

my_calculated_variable:
  multi: true
  default:
    variable: _.my_variable
    propertyerror: false
...

Copy two non-multiple variables into a multiple variable:

%YAML 1.2
---
version: 1.1

my_variable_1: val1

my_variable_2: val2

my_calculated_variable:
  default:
    - variable: _.my_variable_1
    - variable: _.my_variable_2

A variable in a dynamically built family can also be used in a calculation.

For example using the variable for a particular identifier:

%YAML 1.2
---
version: 1.1

varname:
  - val1
  - val2

my_dyn_family_{{ identifier }}:
  dynamic:
    - val1
    - val2
  description: 'Describe {{ identifier }}'
  my_dyn_var_{{ identifier }}:
    default:
      type: identifier

all_dyn_var:
  default:
    variable: _.my_dyn_family_val1.my_dyn_var_val1

In this case, we recover the value val1.

Second example using the variable for all identifieres:

%YAML 1.2
---
version: 1.1

varname:
my_dyn_family_{{ identifier }}:
  dynamic:
    - val1
    - val2
  description: 'Describe {{ identifier }}'

  my_dyn_var_{{ identifier }}:
    default:
      type: identifier

all_dyn_var:
  multi: true
  default:
    variable: _.my_dyn_family_.my_dyn_var_
...

In this case, we recover the val1 and val2 list.

Calculation via a identifier

%YAML 1.2
---
version: 1.1

my_dyn_family_{{ identifier }}:
  dynamic:
    - val1
    - val2
  description: 'Describe {{ identifier }}'

  my_dyn_var_{{ identifier }}:
    type: string
    default:
      type: identifier
...

Calculation via an index

%YAML 1.2
---
version: 1.1

family:
  type: sequence

  leader:
    - val1
    - val2

  follower1:
    type: integer
    default:
      type: index
...