Using Decision Builder in ServiceNow using Flow Designer as well as Script include

[vandanasaluja]

Table of Contents

1. Concept

2. Background

3. Prerequisites

4. Decision Table Structure

   • Inputs

   • Conditions

   • Results

   • Decision Rows

5. Implementation Approaches

   • Flow Designer

   • Script Include & Catalog Client Script

6. Code Examples

   • Catalog Client Script (onChange)

   • Script Include

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Concept

A Decision Table in ServiceNow, part of the Decision Builder application, functions like an Excel sheet where:

• Rows represent individual decision entries

• Columns define input conditions and output actions

This allows you to manage complex logic in a structured, maintainable, and scalable format.

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Background

Recently, I faced a requirement to:

• Display Category, Subcategory, and Questions related to the subcategory on a form

• Automatically set the Priority of a request based on the selected question

There were nearly 400 questions to handle, and I needed a solution that was scalable and easy to maintain even by non-technical users.

A Decision Table turned out to be the perfect fit.

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Prerequisites

• Decision Builder plugin activated

• Access to Flow Designer (for server-side execution)

• Basic understanding of GlideAjax (for client-side use)

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Decision Table Structure

To set up the logic:

1. Inputs: Question (from the form)

2. Result Column: Priority (Low, Medium, High)

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Conditions

• If the question belongs to the High Priority list → set Priority = High

• If it belongs to the Medium Priority list → set Priority = Medium

• For all other questions → set default Priority = Low

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Implementation Approaches

Approach 1: Use Flow Designer

• Call the Decision Table using Flow Designer

• Configure the flow to trigger on record creation

• Use the Decision Table to evaluate input and set the priority field

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Approach 2: Use Client Script & Script Include

Useful when you want to dynamically set priority on form change, without waiting for record creation.

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Code Examples

Catalog Client Script – onChange

function onChange(control, oldValue, newValue, isLoading, isTemplate) {

   if (isLoading || newValue === '') {

      return;

   }

 var ga = new GlideAjax('getDecisionChoice');

    ga.addParam('sysparm_name', 'getChoices');

    ga.addParam('sysparm_input', g_form.getValue("questions_related_to"));

    ga.addParam('sysparm_id', g_form.getUniqueValue());

    ga.getXML(getBPDParse);

    function getBPDParse(response) {

        var answer = response.responseXML.documentElement.getAttribute("answer");

    //alert(answer);

       g_form.setValue("priority",answer);

    }

   //Type appropriate comment here, and begin script below

}

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Script Include – getDecisionChoice

var getDecisionChoice = Class.create();

getDecisionChoice.prototype = Object.extendsObject(global.AbstractAjaxProcessor, {

    getChoices: function(input) {

        var inputs = {};

        inputs['u_question_related_to']= this.getParameter("sysparm_input");

//gs.info("question"+this.getParameter("sysparm_input"));

        var dt = new sn_dt.DecisionTableAPI();

        var response = dt.getDecision('2aa12c1ec338a210b5587453e4013116', inputs);

        var result_elements = response.result_elements;

        var u_priority = result_elements.u_priority.getValue();

        //gs.info("priority"+u_priority);

        return u_priority;

    },

    type: 'getDecisionChoice'

});

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Conclusion

Using Decision Tables with Flow Designer or GlideAjax allows for a scalable and maintainable way to drive logic based on dynamic inputs like questions. This is especially helpful in catalog or case management scenarios where decision logic can change frequently and needs to be managed outside of complex scripts.One Issue which I have faced while Implementation is "My Question Choice" value is greater than 40 in some scenarios so it was not working for them  so make sure if you are using "is one of" operator in Condition of decision builder input then  max length of choice should be less than 40 and it should not include any commas.