QueryOpensearch

OpenSearch Templates

You can use templates in OpenSearch to repeatedly run a certain query using different parameters. For example, if we have an index full of parks, and we want to search for a certain park, we might use a template like this:

{
  "source": {
    "query": {
      "match_phrase": {
        "park_name": "{{park_to_search}}"
      }
    }
  }
}

In Opensearch, you could then call this template (providing it park_to_search) instead of writing out the full query each time you want to search.

Templates can also have default values. For example, if you want park_to_search to default to “Central Park” when a value is not provided, it would be written as: "park_name": "{{park_to_search}}{{^park_to_search}}Central Park{{/park_to_search}}"

QueryOpensearch Stage

The QueryOpensearch Stage executes a search template using certain fields from a Document as your parameters and adding OpenSearch’s response to the Document. You’ll specify either templateName, the name of a search template you’ve saved, or searchTemplate, the template you want to execute, in your Config.

You’ll also need to specify the names of parameters in your search template. These will need to match the names of fields on your Documents. If your names don’t match, you can use the RenameFields Stage first.

In particular, you have to specify which parameters are required and which are optional. If a required name in requiredParamNames is missing from a Document, an Exception will be thrown, and the template will not be executed. If an optional name in optionalParamNames is missing they (naturally) won’t be part of the template execution, so the default value will be used by OpenSearch.

If a parameter without a default value is missing, OpenSearch doesn’t throw an Exception - it just returns an empty response with zero hits. So, it is very important that requiredParamNames and optionalParamNames are defined very carefully!