Business rules and script includes
Summarize
Summary of Business rules and script includes
Business Rules in ServiceNow are server-side scripts that execute during Create, Read, Update, Delete (CRUD) operations on records. They help automate processes such as setting field values, validating data, triggering notifications, and updating related records. Script Includes are reusable server-side JavaScript functions or classes that encapsulate logic for use across multiple scripts, including Business Rules, UI Actions, workflows, and APIs.
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Key Features
- Business Rules Execution Timing:
- Before: Runs synchronously before a database operation to set or validate values.
- After: Runs synchronously after database changes, useful for updating related records or triggering notifications.
- Async: Runs asynchronously after database operations, ideal for long-running processes or external system calls without delaying user actions.
- Display: Executes every time a form is displayed, enabling server-side data to be sent to client scripts.
- Best Practices for Business Rules:
- Keep Business Rules small and focused on specific tasks.
- Avoid modifying out-of-the-box Business Rules directly.
- Use conditions to control when Business Rules execute, improving efficiency and debugging.
- Avoid client-callable Business Rules to enhance client script performance.
- Use queries within Business Rules to limit processed records.
- Do not use
current.update()in Business Rules to prevent recursive loops and duplicate notifications.
- Script Includes:
- Store reusable server-side JavaScript logic as functions or classes.
- Enable code reuse across multiple script types like Business Rules, UI Actions, workflows, and Scripted REST APIs.
- Facilitate easier testing and maintenance by centralizing shared functionality.
- Recommended to call Script Includes instead of invoking Business Rules directly from UI Actions or APIs.
Key Outcomes
- Efficient, maintainable server-side automation that complements client-side interactions.
- Reduced duplication and improved code reuse through the use of Script Includes.
- Better performance and control over when and how server-side scripts execute.
- Improved debugging and error handling by using conditions and avoiding recursive updates.
- Enhanced ability to integrate with external systems asynchronously without impacting user experience.
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. |
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.