TypeScript Yup: Expected 0 arguments, but got 1.ts(2554) - A Comprehensive Guide
This article will address a common error encountered when using Yup validation schemas with TypeScript: "Expected 0 arguments, but got 1.ts(2554)". We'll explain the cause, provide a solution, and offer insights on improving your Yup validation in TypeScript projects.
Understanding the Error
The error message "Expected 0 arguments, but got 1.ts(2554)" arises from a misunderstanding of how Yup's string() function works in TypeScript. While Yup's string() function can accept a string as an argument, this string isn't meant for an error message. It's used to specify a specific type of string, such as a URL or an email address.
The Source of the Issue
The provided code snippet demonstrates this mistake:
import * as Yup from "yup";
export const ValidationSchema = {
AddUserSchema = Yup.object().shape({
username: Yup.string('Provide a username').required('Username is required'),
// Here, 'Provide a username' is causing the error
email: Yup.string().email('Provide a valid email address'),
// ...
}),
// ...
};
The Yup.string('Provide a username') line is incorrect because the string() function is meant to be used without any arguments when creating a generic string schema. You should use the label() function for adding custom error messages.
The Solution: Using label() for Error Messages
To resolve the error and properly add error messages, use the label() function within your Yup schema:
import * as Yup from "yup";
export const ValidationSchema = {
AddUserSchema: Yup.object().shape({
username: Yup.string().label('Username').required('Username is required'),
// Use label() to provide error messages
email: Yup.string().email().label('Email').required('Email is required'),
// ...
}),
// ...
};
Best Practices for Yup and TypeScript
- Use Type Safety: TypeScript allows you to define the types of your Yup schemas for improved code clarity and reduced errors.
- Separate Validation Logic: Keep your validation schemas separate from your component logic for better code organization and reusability.
- Custom Validation Functions: Use Yup's
test()function to implement custom validation logic for complex scenarios. - Clear Error Messages: Provide informative and user-friendly error messages that help users understand what went wrong.
Example: Implementing Custom Validation
Here's an example of how to use Yup's test() function for custom validation:
import * as Yup from "yup";
const passwordSchema = Yup.string()
.required('Password is required')
.test('password-strength', 'Password must be at least 8 characters long and contain at least one uppercase letter, one lowercase letter, and one number.', value => {
// Implement your custom password strength validation logic here
return value && value.length >= 8 &&
/[A-Z]/.test(value) &&
/[a-z]/.test(value) &&
/\d/.test(value);
});
export const ValidationSchema = {
// ...
};
In Conclusion
By understanding the proper use of Yup functions in TypeScript, you can create robust and type-safe validation schemas for your applications. Remember to separate validation logic, utilize custom validation functions, and provide clear error messages for a user-friendly experience.
References
- Stack Overflow Question: https://stackoverflow.com/questions/71869371/typescript-yup-expected-0-arguments-but-got-1-ts2554
- Yup Documentation: https://github.com/jquense/yup
