mst-validation

A validation library for mobx-state-tree.

Installation

npm install mobx mobx-state-tree mst-validation

Usage

Intersection type

import { rules, validate } from 'mst-validation';

const minLength = (min: number) =>
    types.refinement(
        types.string,
        (v) => v.length >= min,
        () => 'minLength'
    );
const maxLength = (max: number) =>
    types.refinement(
        types.string,
        (v) => v.length <= max,
        () => 'maxLength'
    );

const minOneMaxFive = rules.intersection(minLength(1), maxLength(5));

const result = validate(minOneMaxFive, 'a long message');
expect(result.success).toBe(false);
expect(result.error.issues[0].code).toBe('intersection');
expect(result.error.issues[1].code).toBe('maxLength');

Debugging

Error messages in mobx-state-tree can sometimes be difficult to read. With validate and you get an object representation of where the errors happened, which can be easier to digest for complex models.

const DogModel = types.model({
    name: validators.name,
    age: validators.age,
});

const CatModel = types.model({
    name: validators.name,
    age: validators.age,
    breed: types.enumeration(['Abyssinian Cat', 'Bengal Cat']),
});

const UserModel = types.model({
    name: validators.name,
    age: validators.age,
    interests: rules.intersection(
        types.string,
        rules.validation(minLength(1), () => 'Not long enough')
    ),
    animals: types.array(types.union(CatModel, DogModel)),
});

const { success, issues } = validate(UserModel, {
    name: 'Kim',
    age: 37,
    interests: 2,
    animals: [
        { name: 'Mephisto', age: 3, breed: 'Bengal Cat' },
        { name: 'Catdog', breed: 'Golden retriever' },
        { name: 'Eddie', age: 4 },
    ],
});