Ensuring Data Integrity in Custom Scoped Applications with Contractual

Building custom scoped applications in ServiceNow, it is important to make sure data is clean, consistent, and fits the expected format. IMO – ServiceNow doesn’t do enough to enforce data validation. To amend that, I wrote Contractual.

What is Contractual?

Contractual is a handy script include for consistent data validation. You can wrap variables or objects and run all kinds of checks on them. If something’s off, it throws a clear error. Its fluent interface makes validation code neat and readable.

Some things Contractual can do:

• Type Checks: Make sure values are the right type (isTypeOf, isInstanceOf).
• Null and Empty Checks: Catch empty or missing values (isNotNull, isNotEmpty).
• Range and List Checks: Validate numbers, array lengths, or allowed values (isAtLeast, isOneOf).
• Schema Validation: Check objects or arrays against a prototype or schema (isObjectSchema, isArrayOf$ObjSchema).
• ServiceNow-Specific Checks: Validate GlideRecord instances and table data (isGlideRecord, isOneOf$Table).

Why bother with data validation?

Custom apps often deal with user inputs, integrations, and workflows. Without solid validation, you can run into:

1. Errors at runtime: Bad data can break scripts or flows.
2. Corrupted data: Bad data spreads through tables and reports.
3. Security risks: Malformed input can cause unwanted behavior.
4. Maintenance headaches: Debugging messy data is a pain, especially across scopes.

With Contractual, you catch issues early, get clear error messages, and keep data consistent across your app.

Why Contractual is handy

• Easy-to-read code: Chaining methods makes validation statements clean.
• Cross-scope friendly: Works reliably even when objects move across scoped boundaries.
• Helpful errors: Tells you which variable failed, why, and what was expected.
• Flexible: You can add your own checks if needed.

var userInput = {
    name: 'Alice',
    age: 30,
    roles: ['admin', 'editor']
};

try {
    new x_myscope.Contractual(userInput, 'User Input')
        .isNotNull()
        .isObjectSchema(['name', 'age', 'roles']);
} catch (ex) {
    gs.error(ex.message);
}

Wrap-up

In ServiceNow, validation is often an after thought. However, it’s key to building apps that are reliable, maintainable, and safe. The Contractual script include allows for consistent enforcement of data rules, helping you catch problems early and keep your app running smoothly.

Use it consistently and you’ll save yourself a lot of headaches down the road.