Lead Maintainer: Nicolas Morel
Imagine you run facebook and you want visitors to sign up on the website with real names and not something like
l337_p@nda in the first name field. How would you define the limitations of what can be inputted and validate it against the set rules?
See the detailed API Reference.
const Joi = ;const schema = Joiobject;// Return result.const result = Joi;// result.error === null -> valid// You can also pass a callback which will be called synchronously with the validation result.Joi; // err === null -> valid
The above schema defines the following constraints:
- a required string
- must contain only alphanumeric characters
- at least 3 characters long but no more than 30
- must be accompanied by
- an optional string
- must satisfy the custom regex
- cannot appear together with
- an optional, unconstrained string or number
- an integer between 1900 and 2013
- a valid email address string
- must have two domain parts e.g.
Usage is a two steps process. First, a schema is constructed using the provided types and constraints:
const schema =a: Joi;
Note that joi schema objects are immutable which means every additional rule added (e.g.
.min(5)) will return a
new schema object.
Second, the value is validated against the defined schema:
const error value = Joi;// orJoi;
If the input is valid, then the
error will be
null, otherwise it will be an
Error object providing more information.
const schema = Joi;
If the schema is a joi type, the
schema.validate(value, callback) can be called directly on the type. When passing a non-type schema object,
the module converts it internally to an object() type equivalent to:
const schema = Joiobject;
When validating a schema:
Values (or keys in case of objects) are optional by default.Joi; // validates fine
To disallow this behavior, you can either set the schema as
required(), or set
Strings are utf-8 encoded by default.
Rules are defined in an additive fashion and evaluated in order, first the inclusive rules, then the exclusive rules.
Joi doesn't directly support browsers, but you could use joi-browser for an ES5 build of Joi that works in browsers, or as a source of inspiration for your own builds.