Business rules and script includes
Summarize
Summary of Business rules and script includes
Business rules in ServiceNow are server-side scripts that run during CRUD (Create, Read, Update, Delete) operations on records. They enable automation and data manipulation before or after database actions, asynchronously, or when displaying forms. Script Includes are reusable JavaScript functions or classes stored for use across multiple server-side scripts, promoting code reuse and easier maintenance.
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Key Features
- Business Rules Execution Timings:
- Before: Runs synchronously before the database operation to set or validate record values.
- After: Runs synchronously after the database operation to trigger events or update related records.
- Async: Runs asynchronously after the database operation, suitable for long-running tasks or external processes.
- Display: Runs every time a form is displayed to make server-side data available to client scripts.
- Best Practices for Business Rules:
- Keep rules small and specific.
- Avoid modifying base system Business Rules.
- Use Script Includes instead of global Business Rules for reusable logic.
- Use conditions to control when Business Rules run, aiding performance and debugging.
- Limit records processed with queries inside Business Rules.
- Avoid calling current.update() inside Business Rules to prevent recursive database operations.
- Avoid client-callable Business Rules for efficiency.
- Script Includes:
- Store reusable server-side JavaScript functions and classes.
- Called from Business Rules, UI Actions, workflows, and Scripted REST APIs.
- Facilitate centralized code management and testing, reducing overall development time.
- Preferred over calling Business Rules directly from UI Actions or REST APIs.
Practical Guidance for ServiceNow Customers
When automating record processing, use Business Rules with appropriate conditions and execution timing to optimize performance and maintainability. For reusable logic across multiple scripts or interfaces, place your JavaScript functions in Script Includes. This approach enhances code reuse, simplifies testing, and avoids common pitfalls such as recursive updates or inefficient client-server interactions.
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.