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Storing custom data within the data model

Background

This article describes how to add custom data to the data model using a hook script. Once the custom values are in the data model they can be accessed from a Freemarker template.

Custom data elements in the data model

If you need to store variables within the data model there are several customData maps that exist for this purpose:

  • transaction.question.customData[]: Custom data to attach to the search question. Values can be added in a pre-process hook script.

  • transaction.response.customData[]: Custom data to attach to the search response. Values can be added in a post-process hook script.

  • transaction.response.results[n].customData[]: Result-specific custom data. Per result values can be added in a post-process hook script.

  • transaction.customData[]: Global custom data. Note: this is not currently accessible from Freemarker so don’t use this element.

Adding custom data

The following example shows how to set a few different types of variables in a post process hook script and write these to the response.customData[] list in the data model:

hook_post_process.groovy
// Define some variables of different types
def number = 3
def string = "This is a string value"
def map=[ident1:"val1", ident2:"val2"]
def list=["item","another item"]

// Add these to custom data in the data model
transaction.response.customData["number"] = number
transaction.response.customData["string"] = string
transaction.response.customData["list"] = list
transaction.response.customData["map"] = map

This results in a data model structure like the following (note: some of the data model elements have been collapsed for clarity in the example:

search.json
{
	question: { ... },
	extraSearchesTerminated: false,
	response: {
		resultPacket: { ... },
		returnCode: 0,
		untruncatedPadreOutputSize: 11906,
		facets: [ ... ],
		customData: {
			number: 3,
			string: "This is a string value",
			list: [
				"item",
				"another item"
				],
			map: {
				ident1: "val1",
				ident2: "val2"
				}
		},
		optimiserModel: null,
		curator: { ... },
		performanceMetrics: { ... }
	},
	session: { ... },
	QueryString: "collection=mycollection&query=!showall",
	error: null
}