🛠️ Built-in Validation Rules

Base Rules

r.required('Custom message')      // Field is mandatory
r.email()                         // Valid email format
r.minLength(5)                    // Minimum string length
r.maxLength(100)                  // Maximum string length
r.numeric()                       // Only digits allowed
r.regex(/pattern/, 'message')     // Custom regex pattern
r.oneOf(['a', 'b', 'c'])          // Must be one of the specified values

Numeric Rules

r.minValue(0)                     // Minimum value
r.maxValue(100)                   // Maximum value
r.between(0, 100)                 // Inclusive range of values

Cross-field Rules

r.sameAs('password')              // Must match another field's value
r.dateAfter('startDate')          // Date must be after another field's date
r.requiredIf('type', 'business')  // Required if another field matches a specific value

File Rules

r.fileRequired()                  // File selection is mandatory
r.fileSize(5 * 1024 * 1024)       // Maximum file size (5MB)
r.fileType(['.jpg', '.png'])      // Allowed file extensions
r.fileCount(1, 5)                 // Range for number of files

Array Rules

r.arrayRequired()                 // Checks if value is an array with at least one element
r.arrayMinLength(1)               // Minimum array length
r.arrayMaxLength(10)              // Maximum array length

Note: arrayRequired() and arrayMinLength(1) function identically, but arrayRequired() provides a more semantic name for mandatory arrays.

Advanced Rules

// Remote validation with debouncing
r.remote(
  async username => {
    const response = await fetch(`/api/check-username/${username}`)
    return response.ok
  },
  'Username is already taken',
  500
)

// Custom validation
r.custom((value, allValues) => {
  return value.includes(allValues.domain)
}, 'Invalid format')