Options validator using [`ow`](https://github.com/sindresorhus/ow).
# Features
* If used with a type argument, validates the provided `ow` spec against the provided type, ensuring
that your runtime type checking stays in sync with your compile-time type-checking.
* If used without a type argument, ensures that validated values conform to the shape of the provided
`ow` spec.
* Uses Levenshtein distance to suggest correct names for misspelled keys (a-la Jest, Babel).
* Allows for optional defaults to be specified, which are merged with user input before validation.
## Install
```
npm install @darkobits/valida
```
## Use
```ts
import createValidator from '@darkobits/valida';
interface Person {
name: string;
address: {
street: string;
locality: string;
postalCode: string;
administrativeArea: string;
countryCode?: string;
}
age: number;
}
/**
* - Pass a function to `createValidator`. This function will be invoked with a
* context object containing an `ow` reference.
* - By default, `validate` will try to return the right shape based on your
* spec object, but if you need to be precise, provide a type argument to
* `createValidator` with your expected return type.
*/
const validate = createValidator(({ ow }) => ({
/**
* - Return an object containing a `spec` property and an optional `defaults`
* property.
* - Note: Validation will take place _after_ defaults have been merged with
* user-provided data, so any fields for which you provide defaults should
* not use the `optional` predicate. You can, however, mark those fields as
* optional in your type defs so the user doesn't yelled-at if they omit a
* field with a default value.
*/
spec: {
name: ow.string,
address: ow.object.exactShape({
street: ow.string,
locality: ow.string,
postalCode: ow.string.numerical,
administrativeArea: ow.string,
countryCode: ow.string.maxLength(2)
}),
age: ow.number.positive
},
defaults: {
address: {
countryCode: 'GB'
}
}
}));
// - `person` will be of type `Person`
// - `address.CountryCode` will be merged-in.
const person = validate({
name: 'Ervin Howell',
address: {
street: '692 Victor Plains',
locality: 'Gwenborough',
postalCode: '44932',
administrativeArea: 'Chestertonshire',
}
});
// This will throw; postalCode is non-numeric.
const person = validate({
name: 'Ervin Howell',
address: {
street: '692 Victor Plains',
locality: 'Gwenborough',
postalCode: 'kittens',
administrativeArea: 'Chestertonshire',
}
});
```
## See Also
* [`ow`](https://github.com/sindresorhus/ow)
