Skip to main content

Conditional Validation

Advanced conditional validation patterns for complex scenarios.

Basic Conditional Validation​

// Field is required if another field exists
v.string().requiredWith("email")

// Field is required if another field equals a value
v.string().requiredIf("type", "admin")

// Field is required unless another field equals a value
v.string().requiredUnless("type", "guest")

// Field must be present if another field exists
v.string().presentWith("email")

Complex Conditional Logic​

// Required if all fields exist
v.string().requiredWithAll(["email", "phone"])

// Required if any field exists
v.string().requiredWithAny(["email", "phone"])

// Required if field value is in array
v.string().requiredIfIn("type", ["admin", "moderator"])

// Required if field is empty
v.string().requiredIfEmpty("email")

When Rules​

v.string().when("type", {
  is: {
    admin: v.string().required().minLength(5),
    user: v.string().required().minLength(3)
  },
  otherwise: v.string().optional()
})

Real-World Example​

const userSchema = v.object({
  type: v.string().required().oneOf(["admin", "user", "guest"]),
  email: v.string().optional().email(),
  phone: v.string().optional(),
  name: v.string().requiredUnless("type", "guest"),
  role: v.string().requiredIf("type", "admin"),
  address: v.string().requiredWithAll(["email", "phone"])
});

Advanced Patterns​

const schema = v.object({
  type: v.string().required().oneOf(["admin", "user"]),
  profile: v.object({
    name: v.string().required(),
    email: v.string().required().email(),
    role: v.string().when("type", {
      is: {
        admin: v.string().required().oneOf(["super", "moderator"]),
        user: v.string().required().oneOf(["member", "guest"])
      }
    })
  })
});

Error Handling​

v.string()
  .requiredIf("type", "admin", "Admin role is required")
  .requiredWith("email", "Name is required when email is provided")
  .requiredUnless("type", "guest", "Role is required for registered users")

Best Practices​

// ✅ Good: Check simple conditions first
v.string()
  .required()           // Simple check first
  .minLength(3)         // Then length
  .when("type", {       // Complex condition last
    is: { admin: v.string().minLength(5) }
  })

// ✅ Good: Efficient conditional logic
v.string()
  .requiredIf("type", "admin")
  .minLength(3)
  .maxLength(20)

Testing​

// Test different user types
const adminData = { type: "admin", role: "super", name: "John Doe" };
const userData = { type: "user", role: "member", name: "Jane Doe" };
const guestData = { type: "guest", name: "Guest User" };

const adminResult = await validate(schema, adminData);
const userResult = await validate(schema, userData);
const guestResult = await validate(schema, guestData);

See Also​