Object validation is a tricky thing. It sounds pretty simple when you first think about it, yet there are a ton of libraries that try to do it. Why is that? I feel like there are just alot of way to approach the subject. joi is a schema validation library that came out of the Walmart Labs efforts and more specifically power validation in the hapi server framework.
Lets check it out!
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npm install joi |
Usage
joi works by defining a schema. You can validate a single string or number:
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var Joi = require('joi');// will failJoi.string().validate(10, console.log);// also will failJoi.string().email().validate('hello+gmail.com', console.log);// will passJoi.string().email().validate('hello+world@gmail.com', console.log); |
You can validate a basic plain schema
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var schema = {counter: Joi.number().min(1).max(10).required()};// will failJoi.validate({counter: 0}, schema, console.log);// will passJoi.validate({counter: 5}, schema, console.log); |
Finally, you can do a some pretty complicated validation with fields depending on each other:
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var schema = Joi.object().keys({ username: Joi.string().alphanum().min(3).max(30).required(), password: Joi.string().regex(/[a-zA-Z0-9]{3,30}/), confirmation: Joi.ref('password') }) .with('password', 'confirmation');// will fail because `foo` isn't in the schema at allJoi.validate({foo: 1}, schema, console.log);// will fail because `confirmation` is missingJoi.validate({username: 'alex', password: 'qwerty'}, schema, console.log);// will passJoi.validate({ username: 'alex', password: 'qwerty', confirmation: 'qwerty'}, schema, console.log); |
Closing thoughts
Here are some other modules you might want to evaluate:
- validator is a string validation and sanitization module by Chris O’Hara.
- finito is a language for capturing information structure by Louis Lambeau.
- schema-inspector is a module to sanitize and validate objects by Sébastien Chopin (previously featured on npmawesome.com).
Finally, check out source code for this article on GitHub and an interative example on Runnable.