regex

Summary

Sails allows custom validation rules using regular expressions (regex). This is useful when built-in rules (isEmail, isNumber, etc.) aren’t enough.

For example, if you're building an internal tool for Sailscasts, you may want to only allow emails from sailscasts.com.

Example: Restricting Email to a Specific Domain

To enforce this rule in a Sails model, define the attribute like this:

workEmail: {
  type: 'string',
  regex: /^w+@sailscasts\.com$/i
}

Key Takeaways:

Use regex for custom validation where built-in rules don’t apply.
Regular expressions provide more flexibility for specific use cases.
Common examples include:
- Enforcing a company domain for emails.
- Custom password complexity rules.
- Matching specific number formats.

Testing the Validation Rule

Invalid Email

await User.create({ workEmail: "user@gmail.com" });

❌ Fails validation because it's not from sailscasts.com.

Valid Email

await User.create({ workEmail: "kelvin@sailscasts.com" });

✅ Passes, because it matches the required domain.

Case-Insensitive Match

await User.create({ workEmail: "Kelvin@Sailscasts.com" });

✅ Passes, because i flag makes it case-insensitive.

Transcript

So far, we've looked at validation rules like isEmail, isString, and isNumber, which just take true or false values. But what if you need something more custom—something specific to your application?

For example, you might want to ensure that only emails from sailscasts.com are allowed. Sails provides a flexible way to handle this using regular expressions (regex).

Defining a Custom Regex Validation

In our User model, let’s add an attribute for work emails:

workEmail: {
  type: 'string',
  regex: /^w+@sailscasts\.com/i
}

w+ → Matches the username part of the email.
@sailscasts\.com → Ensures the domain is exactly sailscasts.com.
\. (escaped dot) → Because . in regex means "any character".
i flag → Makes it case-insensitive (Sailscasts.com still works).

Testing the Rule in Guppy

1. First, let’s try an invalid email:

await User.create({ workEmail: "random@gmail.com" });

Fails, because it's not from sailscasts.com.

2. Now, let’s try a valid email:

await User.create({ workEmail: "admin@sailscasts.com" });

Passes, because the domain matches.

3. What about different letter cases?

await User.create({ workEmail: "User@Sailscasts.com" });

Still passes, because the regex is case-insensitive.

When to use regex

Company-specific email validation (like @sailscasts.com).
Password strength validation (custom complexity rules).
Matching phone numbers, postal codes, or custom ID formats.

Final Thoughts

Use regex for custom validation needs.
If you're comfortable with regular expressions, this is a powerful tool.
In the next lesson, we'll look at another way to create custom validation rules.

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