126 lines
4.2 KiB
Markdown
126 lines
4.2 KiB
Markdown
<a href="http://hapijs.com"><img src="https://raw.githubusercontent.com/hapijs/assets/master/images/family.png" width="180px" align="right" /></a>
|
|
|
|
# joi
|
|
|
|
Object schema description language and validator for JavaScript objects.
|
|
|
|
[](https://travis-ci.org/hapijs/joi)
|
|
|
|
## Introduction
|
|
|
|
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?
|
|
|
|
This is joi, joi allows you to create *blueprints* or *schemas* for JavaScript objects (an object that stores information) to ensure *validation* of key information.
|
|
|
|
# Installation
|
|
|
|
```cli
|
|
npm install --save @hapi/joi
|
|
```
|
|
|
|
## API
|
|
See the detailed [API Reference](https://github.com/hapijs/joi/blob/v15.1.0/API.md).
|
|
|
|
## Example
|
|
|
|
```javascript
|
|
const Joi = require('@hapi/joi');
|
|
|
|
const schema = Joi.object().keys({
|
|
username: Joi.string().alphanum().min(3).max(30).required(),
|
|
password: Joi.string().regex(/^[a-zA-Z0-9]{3,30}$/),
|
|
access_token: [Joi.string(), Joi.number()],
|
|
birthyear: Joi.number().integer().min(1900).max(2013),
|
|
email: Joi.string().email({ minDomainSegments: 2 })
|
|
}).with('username', 'birthyear').without('password', 'access_token');
|
|
|
|
// Return result.
|
|
const result = Joi.validate({ username: 'abc', birthyear: 1994 }, schema);
|
|
// result.error === null -> valid
|
|
|
|
// You can also pass a callback which will be called synchronously with the validation result.
|
|
Joi.validate({ username: 'abc', birthyear: 1994 }, schema, function (err, value) { }); // err === null -> valid
|
|
|
|
```
|
|
|
|
The above schema defines the following constraints:
|
|
* `username`
|
|
* a required string
|
|
* must contain only alphanumeric characters
|
|
* at least 3 characters long but no more than 30
|
|
* must be accompanied by `birthyear`
|
|
* `password`
|
|
* an optional string
|
|
* must satisfy the custom regex
|
|
* cannot appear together with `access_token`
|
|
* `access_token`
|
|
* an optional, unconstrained string or number
|
|
* `birthyear`
|
|
* an integer between 1900 and 2013
|
|
* `email`
|
|
* a valid email address string
|
|
* must have two domain parts e.g. `example.com`
|
|
|
|
## Usage
|
|
|
|
Usage is a two steps process. First, a schema is constructed using the provided types and constraints:
|
|
|
|
```javascript
|
|
const schema = {
|
|
a: Joi.string()
|
|
};
|
|
```
|
|
|
|
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:
|
|
|
|
```javascript
|
|
const {error, value} = Joi.validate({ a: 'a string' }, schema);
|
|
|
|
// or
|
|
|
|
Joi.validate({ a: 'a string' }, schema, function (error, value) { });
|
|
```
|
|
|
|
If the input is valid, then the `error` will be `null`, otherwise it will be an `Error` object providing more information.
|
|
|
|
The schema can be a plain JavaScript object where every key is assigned a **joi** type, or it can be a **joi** type directly:
|
|
|
|
```javascript
|
|
const schema = Joi.string().min(10);
|
|
```
|
|
|
|
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:
|
|
|
|
```javascript
|
|
const schema = Joi.object().keys({
|
|
a: Joi.string()
|
|
});
|
|
```
|
|
|
|
When validating a schema:
|
|
|
|
* Values (or keys in case of objects) are optional by default.
|
|
|
|
```javascript
|
|
Joi.validate(undefined, Joi.string()); // validates fine
|
|
```
|
|
|
|
To disallow this behavior, you can either set the schema as `required()`, or set `presence` to `"required"` when passing `options`:
|
|
|
|
```javascript
|
|
Joi.validate(undefined, Joi.string().required());
|
|
// or
|
|
Joi.validate(undefined, Joi.string(), /* options */ { presence: "required" });
|
|
```
|
|
|
|
* 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.
|
|
|
|
## Browsers
|
|
|
|
Joi doesn't directly support browsers, but you could use [joi-browser](https://github.com/jeffbski/joi-browser) for an ES5 build of Joi that works in browsers, or as a source of inspiration for your own builds.
|