Business rules and script includes

  • Release version: Xanadu
  • Updated August 1, 2024
  • 2 minutes to read
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    Summary of Business rules and script includes

    Business Rules in ServiceNow are server-side scripts that execute during CRUD (Create, Read, Update, Delete) operations on records. They enable automated processing and validation when records are created, updated, or accessed. Script Includes are reusable server-side JavaScript functions or classes designed to store logic that can be shared across multiple server scripts such as Business Rules, UI Actions, workflows, and APIs.

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    Key Features

    • Business Rules Execution Timing: They can run before or after database operations, asynchronously after completion, or when displaying a form to expose server-side data to client scripts.
    • Best Practices for Business Rules: Keep them small and specific, avoid modifying system base Business Rules, prefer Script Includes over global Business Rules, use conditions to control execution and aid debugging, avoid client-callable Business Rules for efficiency, and limit the records processed with queries.
    • Script Includes Usage: Store reusable functions or classes to centralize logic. Call Script Includes from multiple places such as Business Rules, UI Actions, and Scripted REST APIs to reduce code duplication and simplify testing.

    Key Outcomes

    • Efficient and Controlled Automation: By setting conditions and timing for Business Rules, processes can be optimized to run only when needed, reducing performance impact and preventing issues like recursive loops.
    • Reusable Code and Faster Development: Script Includes promote modularity and reusability, allowing developers to maintain and test logic in one place, accelerating deployment across various server-side scripts.
    • Improved Client-Server Interaction: Display Business Rules can pass server-side data to client scripts via objects like gscratchpad, enhancing client-side functionality without compromising performance.

    Business rules are server-side actions that can be run during CRUD (Create, Read, Update, Delete) operations on instance records.

    Some good practices when using Business Rules are:

    • Keep Business Rules small and specific.
    • Avoid modifying base system Business Rules.
    • Use Script Includes instead of global Business Rules.
    • Use scripting only when necessary.
    • Store reusable script logic in a script include.
    • Use queries to limit records processed within a Business rule.
    • Avoid client-callable Business Rules to improve efficiency when running client scripts.
    • Always use a condition with Business Rules to control when the Business Rule runs. Running Business Rules with conditions can also aid in debugging. Business Rules rarely run with no conditions.

    Business Rules can be configured to run before or after a database operation. They can also be configured to run asynchronously and also before displaying a form or executing a query.

    Value Runs When to Use Example
    Before Synchronously before the database operation Set or update values on the current object as part of the save operation. Validate and abort execution if required. A developer wants to set the state of the current record based on another input in that record.
    After Synchronously after the database operation Trigger events and notifications after the database update to access the previous object or to make something occur in sequence. Update related records other than the base table being updated to access the previous object or to make something occur in sequence. A developer wants to cascade values from the current record down to child records.
    Async Asynchronously executed as a separate process after the database operation is completed The process triggered by the rule may take a while to run. When the user who triggered the operation does not need the output right away. Trigger events, notifications, or related record updates when access to the previous values of the record or a specific sequence of actions is not required. A developer needs to trigger an external process that may take a while or update a large number of records.
    Display Executed every time the corresponding form is displayed Used to make server-side objects available to client-side scripts. A developer wants to write information about a user associated with the current record to the g_scratchpad object to use in a client-side script.
    Note:
    current.update()should not be used in any Business Rules. Using current.update()triggers an additional database operation, which could cause duplicate notifications, recursive loops, etc.

    Use Script Includes to store JavaScript functions and classes for use by server scripts. Each Script Include defines either an object class or a function that can be reused among any server-side scripts. For more information, see Script includes.

    Store any code that might need to be used elsewhere in a Script Include. Call the Script Include from a Business Rule, UI Action, workflow script, Scripted REST API, etc. Instead of calling a Business Rule from a UI Action or a UI Action from a Scripted REST API, put the code in a Script Include and call the Script Include from both places.

    Keeping functions in a Script Include allows testing of the function before deploying the function in other scripted areas, thus reducing overall development and testing time.

    For more information, see Classic Business rules.