Schema - Regex (String)

The .regex method in Schema allows you to validate if a string conforms to a given regular expression pattern. This method is flexible and can be used for any custom string validation that requires a specific format, such as email validation, URL validation, or alphanumeric constraints.

Using .regex, you can ensure that the input data matches the desired pattern before proceeding with the application logic. Additionally, you can customize error messages when the validation fails.

Example

Below is an example of how to use .regex to validate if a string matches a regular expression pattern for email validation:

import { schema } from "vkrun"
 
const regex = /^[a-zA-Z0-9._-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,}$/
 
const schemaValidation = schema()
  .string()
  .regex(regex)
 
const validateA = schemaValidation.validate("any_email@domain.com")
const validateB = schemaValidation.validate("invalid_email@domain")
 
console.log(validateA) // true
console.log(validateB) // false

In this example:

• We define a regular expression pattern for validating an email address. The .regex() method is used to apply the validation.
• The method returns true if the email is valid and false otherwise.

Customizing Error Messages

You can customize the error message returned when the validation fails by using the errorMessage option. This allows you to define a specific message that will be included in the error response. You can also use placeholders such as [value] and [valueName] to dynamically insert values into the error message.

const schemaValidation = schema()
  .string()
  .regex(regex, {
    errorMessage: "The email [value] is invalid!" // custom error message
  })

In this example:

• [value] is a placeholder for the actual value being validated (in this case, the email).
• If the input does not match the regex pattern, the custom error message "The email [value] format is invalid!" will be used, where [value] will be replaced with the invalid email address.

Available Keywords for Customizing Error Messages

You can use the following keywords for customizing the error message:

• [value]: Represents the actual value that is being validated.
• [valueName]: Represents the name you assign to the value, for example, the key in the validation object (e.g., email).