Passing parameters to PaCE policies

  • Release version: Xanadu
  • Updated August 1, 2024
  • 2 minutes to read
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    Summary of Passing parameters to PaCE policies

    This guide explains how to pass parameters to PaCE policies for validating updates to objects within ServiceNow. It covers three types of parameter inputs: API Variables, Config Parameters, and Record References, applicable in both low-code and JavaScript environments.

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    Key Features

    • API Variables: Known as Caller Inputs, these are mandatory variables passed when invoking the PaCE API. They ensure the policy is executed. The only pre-defined API Variable is SnapshotId, which is immutable.
    • Config Parameters: Formerly Mapped Inputs, these parameters can be defined when mapping policies to objects. Mandatory inputs must have specified values; otherwise, the policy remains inactive. An example includes setting different expense limits based on groups.
    • Record References: These allow for queries to extract data from ServiceNow tables, which can be used in policy logic, including performing aggregate functions.
    • Data Collectors: This feature collects input process data from ServiceNow or external sources. The output from data collectors can influence policy decisions and can be managed through the policy builder.

    Key Outcomes

    By effectively using parameters, ServiceNow customers can ensure that their PaCE policies are dynamic and tailored to specific scenarios, enabling precise validations and decision-making processes based on the data collected and parameters defined.

    Parameters can be passed to a PaCE policy to validate updates to an object (tables and document IDs). These variables apply to authoring in both low-code or JavaScript. Policy versions include three types of parameter inputs: API Variables, Config Parameters, and Record References.

    API Variables

    Previously known as Caller Inputs, the API Variables is passed to the PaCE API at the time of invocation by a developer. The API Variable is a variable that enables you to pass the value to the policy whenever the policy is invoked. Specify a value for this API Variable when calling the API, otherwise the policy is not executed and no decision is reached. In the code editor, the variable name is apiVars.

    For each PaCE policy, there is only one pre-defined API Variable called SnapshotId. This API Variable is Immutable and cannot be modified or deleted. You cannot define any additional API Variables for a policy.

    Config Parameters

    Previously known as Mapped Inputs, the Config Parameters can be passed when mapping policies to an object (tables and document IDs). When you define a Config Parameter, you are creating a parameter that enables you to pass values to the policy whenever the policy is mapped. If you define mandatory inputs, you must specify values for these inputs when mapping the policy. If the inputs you define are not mandatory, the policy is not executed (the status is set to inactive) and no decision is reached. In the code editor, the variable name is configParams.

    For example, for a travel expenses policy you can add variables to define the limits of different types of expenses. The limits are specified when mapping the policy, and set the limits on the expense when the policy is invoked on this object. The breakfast expense limit for one group of employees could be $25, and for a different group of employees the limit could be $50. Each time the policy is invoked, the expenses are validated by the policy according to the limits specified in the mapping.

    Record References

    Record references define queries to extract data from any ServiceNow® tables and use the data to configure the policy logic. This feature enables you to retrieve additional data that may be required while defining the policy. You can define a query to perform aggregate functions for a record reference. In the code editor, the variable name is recordRefs.

    Data Collectors

    The data collectors function collects input process data from ServiceNow or an external data source to provide an output. The output can be used in the policy logic to make a decision. You can define and manage data collectors by creating, editing, updating, and activating them to your policy builder.

    Data collectors can be accessed by using the dataCollectors object in JavaScript.
    Note:
    Auto-completion lists all possible outputs and data collectors that are available to use.

    While editing a policy in low-code, an output of the configured data collectors is available under the drop-down menu.