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Evaluate template¤

The template operator supports the Jinja templating language. Documentation about Jinja can be found in the official Template Designer Documentation.

Note that support for RDF properties is limited, because Jinja does not support some special characters (in particula colons) in variable names. This makes it impractical to access RDF properties. For this reason, the transformation that precedes the template operator needs to make sure that it generates attributes that are valid Jinja variable names.

Default evaluation¤

By default, the template is evaluated separately for each entity. For each input entity, a output entity is generated that provides a single output attribute, which contains the evaluated template.

Limitation: For the default evaluation, accessing nested paths is not supported. If the preceding transformation contains hierarchical mappings, only the attributes from the root mapping can be accessed.

Full evaluation¤

If ‘full evaluation’ is enabled, the entire input set will be evaluated at once.

The entities variable will contain all input entities and can be iterated over:

{% for entity in entities %}
{{entity.property}}
{% endfor %}

A single output entity will be generated that contains the evaluated template.

If the input entities are hierarchical (typically the case if the input transformation is hierarchical), each entity will be hierarchical as well.

Example iterating over a sequence of books that each contains a list of chapters:

{% for book in entities %}
Book {{book.title}}
{% for chapter in book.chapter %}
Chapter {{chapter.chapterNumber}}
{% endfor %}
{% endfor %}

In this example, the child mapping defines a chapter target property from which it is accessible from the root entities. If the child mapping allows multiple entities, the value of the property will be a list of entities.

Static evaluation¤

The template operator can be used without any inputs. The input port will only appear if a variable referencing an input is used or if the ‘Forward input attributes’ option is enabled. E.g. the use of the ‘entities’ variable in case of the full evaluation would require the connection of an input.

Variables with the scopes ‘execution’, ‘project’ and ‘global’ can be used without the need for an input task/dataset.

Without an input port, the template is evaluated once and a single output entity is generated. An input task/dataset that is still connected to the operator is not read.

Parameter¤

Template¤

The template, using Jinja syntax.

  • ID: template
  • Datatype: template
  • Default Value: None

Output attribute¤

The attribute in the output that will hold the evaluated template.

  • ID: outputAttribute
  • Datatype: string
  • Default Value: output

Full evaluation¤

If enabled, the entire input set will be evaluated at once. The template will receive a hierarchical ‘entities’ variable that can be iterated over. A single output entity will be generated that contains the evaluated template.

  • ID: fullEvaluation
  • Datatype: boolean
  • Default Value: false

Forward input attributes¤

If true, the input attributes will be forwarded to the output.

  • ID: forwardInputAttributes
  • Datatype: boolean
  • Default Value: false

Advanced Parameter¤

Language¤

The template language. Currently, Jinja is supported.

  • ID: language
  • Datatype: string
  • Default Value: jinja

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