Example 1: Retrieving all incident records from an external source

Release version: Washingtondc

Updated February 1, 2024

4 minutes to read

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Summary of Retrieving All Incident Records from an External Source

This guide provides a script definition example for retrieving and caching incident records from an external source using ServiceNow's Remote Table API. It outlines the process to create a REST message to fetch all incidents and transform the data for integration into your instance.

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Key Features

RESTMessageV2 Usage: The script utilizes the RESTMessageV2 API to call an external REST service to get incident data.
Error Handling: The script includes error handling to manage issues that arise during data retrieval, ensuring appropriate error messages are set for user visibility.
Data Transformation: It employs the Transformer API to parse the response, allowing for additional transformations before adding records to the remote table.
Transformer Definition: The script defines a mapping between the external API response fields and the corresponding fields in ServiceNow, ensuring data integrity.

Key Outcomes

By following this example, ServiceNow customers can effectively:

Retrieve and incorporate incident records from external sources into their ServiceNow instance.
Transform and map external data accurately to ensure seamless integration.
Implement robust error handling for better troubleshooting and user experience.

Customers should also ensure that the sysid is correctly mapped to maintain functionality across forms using external data.

These are examples of script definitions you might create for retrieval and caching of data from sources external to your current instance. In this first example, we create a script to load all incident records from an external source.

For Remote Table API information, refer to:

/**
 * Using `v_query`, add the rows to `v_table`
 */
(function executeQuery(v_table, v_query) {

	fetchAllIncidents(v_table, v_query);

	/**
	 * fetch all incidents records from the remote instance
	 */
	function fetchAllIncidents(v_table, v_query) {
		// Uses RestMessage with name 'Remote Instance Incidents' and function 'All Incidents'
		// Create a RestMessage first which calls an external REST service
		try {
			var restMessage = new sn_ws.RESTMessageV2('Remote Instance Incidents', 'All Incidents');
			var response = restMessage.execute();
			var responseBody = response.getBody();
			
			// if REST call ends up in an error, set the last error message which shows up
			// at the bottom of the list view
			if (response.haveError()) {
				v_query.setLastErrorMessage(response.getErrorMessage());
				// can use gs.error() or gs.addErrorMessage() while debugging
				// gs.debug() messages visible in session debugger
				// gs.debug(response.getErrorMessage());
				return;
			}
		} catch (ex) {
			v_query.setLastErrorMessage(ex.message);
			// gs.debug(ex.message);
			return;
		}

		var transformerDefinition = getTransformerDefinition();
		var transformer = new sn_tfrm.Transformer(transformerDefinition, responseBody);
		// transformer parses the responseBody and extracts rows
		while (transformer.transform()) {
			// row is field-value map e.g. { active:"true", number: "INC0000001"}
			var row = transformer.getRow();
			// you may do any additional transformations to the row like GlideDuration, GlideDataTime etc. For example,
			// row.duration = new GlideDuration(row.duration);

			// finally add the row to the remote table
			v_table.addRow(row);
		}
	}

	/**
	 * returns a sn_tfrm.TransformerDefinition, which defines the mapping of the table fields and elements in the response body
	 */
	function getTransformerDefinition() {
		// create a rule list to map a field to its element path
		var ruleList = new sn_tfrm.TransformerRuleList()
			.fromJSON() // the response body is a JSON
			// 'active' field maps to path '$.active'
			.addRule("active", "$.active")
			.addRule("caller_id", "$.caller_id.value")
			.addRule("number", "$.number")
			.addRule("short_description", "$.short_description")
			.addRule("sys_id", "$.sys_id")
			.addRule("updates", "$.sys_mod_count");

		var recordPath = "$.result";
		return new sn_tfrm.TransformerDefinition(ruleList, recordPath);
	}
	
})(v_table, v_query);

These code snippets are of note in this script:

function fetchAllIncidents(v_table, v_query) {
		// Uses RestMessage with name 'Remote Instance Incidents' and function 'All Incidents'
		// Create a RestMessage first which calls an external REST service
		try {
			var restMessage = new sn_ws.RESTMessageV2('Remote Instance Incidents', 'All Incidents');
			var response = restMessage.execute();
			var responseBody = response.getBody();
			
			// if REST call ends up in an error, set the last error message which shows up
			// at the bottom of the list view
			if (response.haveError()) {
				v_query.setLastErrorMessage(response.getErrorMessage());
				// can use gs.error() or gs.addErrorMessage() while debugging
				// gs.debug() messages visible in session debugger
				// gs.debug(response.getErrorMessage());
				return;
			}
		} catch (ex) {
			v_query.setLastErrorMessage(ex.message);
			// gs.debug(ex.message);
			return;
		}

You can create a RestMessage and directly use it in the script. In this example, it uses a RESTMessageV2 API with the name of Remote Instance Incidents, and the function All Incidents, which gets all incident data. Once a response is returned from the server, an error message appears if problems are encountered in the data retrieval.

Note:

To learn more about use of RESTMessageV2 and how to define a direct message, see RESTMessageV2 - Scoped, Global and Direct RESTMessageV2 example.

If no problems are encountered in the data retrieval, it gets the data body for the records.

		var transformerDefinition = getTransformerDefinition();
		var transformer = new sn_tfrm.Transformer(transformerDefinition, responseBody);
		// transformer parses the responseBody and extracts rows
		while (transformer.transform()) {
			// row is field-value map e.g. { active:"true", number: "INC0000001"}
			var row = transformer.getRow();
			// you may do any additional transformations to the row like GlideDuration, GlideDataTime etc. For example,
			// row.duration = new GlideDuration(row.duration);

			// finally add the row to the remote table
			v_table.addRow(row);

It then uses the Transformer API to perform any required data transformations, extracts rows, and then adds a row for each record to the remote table.

/**
	 * returns a sn_tfrm.TransformerDefinition, which defines the mapping of the table fields and elements in the response body
	 */
	function getTransformerDefinition() {
		// create a rule list to map a field to its element path
		var ruleList = new sn_tfrm.TransformerRuleList()
			.fromJSON() // the response body is a JSON
			// 'active' field maps to path '$.active'
			.addRule("active", "$.active")
			.addRule("caller_id", "$.caller_id.value")
			.addRule("number", "$.number")
			.addRule("short_description", "$.short_description")
			.addRule("sys_id", "$.sys_id")
			.addRule("updates", "$.sys_mod_count");

		var recordPath = "$.result";
		return new sn_tfrm.TransformerDefinition(ruleList, recordPath);
	}
	
})(v_table, v_query);

getTransformerDefinition defines the schema of the record in the external API response body. It maps each of the fields in the table script to an element in the external record. Any external data elements outside of this mapping are not supported or retrieved.

Note:

You must map a sys_id in the transformer definition to an element in the external data. In this case, the sys_id is mapped to the external incident sys_id. The maximum length of the sys_id is 32 characters. You do this sys_id mapping so forms that use the external data can operate properly.