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Template expressions are a way to map field values in a document. They are used to configure some Fusion index pipeline stages, query pipeline stages, and messaging services. When the value of a configuration parameter is a template expression, that expression is dynamically evaluated at runtime by the StringTemplate library. Fusion template expressions are delimited by angle bracket characters < and >. The expression consists of the name of a variable in the scope of that component. Since these variables are Java objects, if object foo of type Foo has a field named bar, the expression <foo.bar> will evaluate to the string representation of the contents of field bar. For example, given a PipelineDocument where a field named title has a value of Star Wars, the template expression <doc.title> evaluates to Star Wars.

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Index pipeline stage template expression variables

Index stages have the following variables available:
  • ctx. Context: used to pass variables between stages
  • doc. PipelineDocument: Fusion internal representation of a Solr Document. Please note that if you change this class in ways that affect the serialized form (adding fields, for example) you need to change the deserialization code in GenericJSONDocumentMessageReader.
  • _NOW_. The current time in Solr date format (UTC), such as 2025-01-15T09:30:00.000Z.
For example, <doc.title> returns all values of the title field, concatenated with no separator. To return only the first value of a multi-valued field, use <first(doc.title)>.

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Query pipeline stage template expression variables

Query stages have the following variables available:
  • ctx. Context: used to pass variables between stages
  • request. The query request. Use <request.paramName> to return the values of a request parameter.
  • response. The query response, if one exists.
  • _NOW_. The current time in Solr date format (UTC), such as 2025-01-15T09:30:00.000Z.
For example, <request.q> returns all values of the q request parameter, concatenated with no separator. To return only the first value of a multi-valued parameter, use <first(request.paramName)>.

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Example

Check that a query has an fq filter on a given field for a given value: In the UI, set property name to ids and Property Value to req.hasParam("fq") javascript values

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Messaging services template expression variables

Messages have a set of variables which correspond to the parts of a system message:
  • id
  • to
  • from
  • subject
  • body
  • type
  • schedule
A system message is the result of evaluating the following expression: