Joi
Want to read about the joi JavaScript library. It seems like it would be a great library to use to simplify data validation.
Date Created:
1
23
References
Notes
I want to look into Joi because it was recommended by Socket.IO for validating WebSocket messages sent as JSON and because I think it could help simplify code and make it more readable.
The most powerful schema description language and data validator for JavaScript.
- joi address
- Validate email address and domain
- joi formula
- Math and string formula parser
- joi-date
- Extensions for advance date rules
- joi pinpoint
- Return the filename and line number of the calling function
- joi tlds
- TLDS list for domain validation
joi lets you describe your data using a simple, intuitive, and readable language.
const Joi = require('joi');
const schema = Joi.object({
username: Joi.string() // Username: must be string,
.alphanum() // only contain alphanumeric characters,
.min(3) // at least 3 characters long,
.max(30) // at most 30 characters long,
.required(), // required
password: Joi.string()
.pattern(new RegExp('^[a-zA-Z0-9]{3,30}$')), //optional string that must match pattern
repeat_password: Joi.ref('password'),
access_token: [
Joi.string(),
Joi.number()
],
birth_year: Joi.number() // number between 1900 and 2013
.integer()
.min(1900)
.max(2013),
email: Joi.string() // valud email address string, TLD must be .com or .net
.email({ minDomainSegments: 2, tlds: { allow: ['com', 'net'] } })
})
.with('username', 'birth_year')
.xor('password', 'access_token') // only password or access_token can be included in submission
.with('password', 'repeat_password');
schema.validate({ username: 'abc', birth_year: 1994 });
// -> { value: { username: 'abc', birth_year: 1994 } }
schema.validate({});
// -> { value: {}, error: '"username" is required' }
// Also -
try {
const value = await schema.validateAsync({ username: 'abc', birth_year: 1994 });
}
catch (err) { }
General Usage
Usage is a two steps process:
- A schema is constructed using the provisioned types and constraints:
const schema = Joi.object({
a: Joi.string()
});
- joi schema objects are immutable - every additional rule added will return a new schema object
- The value is validated against the defined schema:
const { error, value } = schema.validate({ a: 'a string' });
If the input is valid, then the error will be undefined. If the input is invalid, error is assigned a ValidationError object providing more information.
When validating a schema:
- Values (or keys in the case of objects) are optional by default
- Strings are
utf-8encoded by default. - Rules are defined in additive fashion and evaluated in order, first the inclusive rules, then the exclusive rules.
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