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mediawikisemantic-mediawiki

How should optional or empty values be handled in Semantic Mediawiki?

I am setting up some templates for a Semantic Mediawiki implementation. Template params are being fed into annotations. However, the values are optional; there's not always going to be a value in every field. This causes trouble with some data types. Specifically, if I have

{{#set:
| Has phone={{{phone}}}
}}

I will get an error of the form URIs of the form *** are not allowed where *** is either {{{phone}}} or whatever default value I try to drop in there. It seems impossible for datatypes like phone or email to be empty. I cannot figure out how to support empty values for these fields in my templates. What is the correct pattern to use for null values in SMW annotations?

Solution

  • You can use the default-value feature of template parameters, but give it a blank default value:

    {{#set:
| Has phone={{{phone|}}}
}}

    (Updated:) Or if you need to prevent it setting anything at all, wrap it in a conditional:

    {{#if: {{{phone|}}}
| {{#set: Has phone={{{phone}}} }}
}}