quicktype-mobx-state-tree

Quicktype to Mobx State Tree bindings

About

quicktypemst generates strongly-typed MobX State Tree models from JSON, JSON Schema, and GraphQL queries, making it a breeze to work with JSON type-safely.

Based on quicktype. To use quicktypemst effectively, it is better to read original quicktype documentation first.

Installation

Install globally

$ npm install -g @radist2s/quicktype-mobx-state-tree

Install locally

$ npm install @radist2s/quicktype-mobx-state-tree --save-dev

CLI Usage

$ quicktypemst [--out FILE] FILE|URL ...
$ quicktypemst --help

Examples

JSON to MST

$ quicktypemst https://blockchain.info/latestblock -o latestblock.ts

Output file: latestblock.ts

/* tslint:disable */
import {types} from 'mobx-state-tree'

export const Latestblock = types.model('Latestblock', {
    hash:        types.string,
    time:        types.number,
    block_index: types.number,
    height:      types.number,
    txIndexes:   types.array(types.frozen()),
})

JSON Schema to MST

Input file: types.schema.json

{
    "$id": "types.schema.json",
    "$schema": "http://json-schema.org/draft-07/schema#",
    "type": "object",
    "properties": {
        "number": {
            "type": "integer"
        },
        "string": {
            "type": "string"
        },
        "date": {
            "type": "string",
            "format": "date-time"
        },
        "enum": {
            "type": "string",
            "enum": ["first", "second", "third"],
            "default": "first"
        }
    }
}

Command

$ quicktypemst -s schema types.schema.json -o types.ts

Output file: types.ts

import {types} from 'mobx-state-tree'

export enum Enum {
    First = 'first',
    Second = 'second',
    Third = 'third'
}

export const Types = types.model('Types', {
    date: types.maybe(types.Date),
    enum: types.maybe(types.enumeration<Enum>('Enum', Object.values(Enum))),
    number: types.maybe(types.number),
    string: types.maybe(types.string)
})

Custom types module source

Sometimes you may need to use custom types for models. For example, let's override Date type by custom type with snapshot pre and postprocessors. The example below will allow you to apply JSON snapshots with the specified date as string in format like 2020-04-04T19:34:58.843Z

$ quicktypemst -s schema types.schema.json -o types.ts --types-module ./my-types.ts

Output file: types.ts

import {types} from './my-types'

...

Custom types module file: my-types.ts

import {types as mstTypes} from 'mobx-state-tree'

type DateSnapshotType = string | null
type DateType = Date | null

export function typeDate() {
    return mstTypes.custom<DateSnapshotType, DateType>({
        name: 'Date',
        fromSnapshot(snapshot: DateSnapshotType): DateType {
            return snapshot === null ? null : new Date(snapshot)
        },
        getValidationMessage(snapshot: string | null): string {
            const isValidTimestamp = snapshot === null || /[^\d\.]+/.test(String(snapshot))

            return isValidTimestamp ? '' : `'${snapshot}' doesn't look like a valid timestamp`
        },
        isTargetType(value: DateSnapshotType | DateType): boolean {
            return value instanceof Date || value === null
        },
        toSnapshot(value: DateType): DateSnapshotType {
            return value ? value.toISOString() : null
        }
    })
}

const {Date: MstDate, ...mstPartialProps} = mstTypes

export const types = {
    ...mstPartialProps,
    get Date() {
        return typeDate()
    }
}

Project npm automation

package.json

{
    "scripts": {
        "gen-models": "quicktypemst -s schema --src src/rest.schema.json -o build/gen/rest.ts --types-module src/custom-types.ts"
    }
}

Usage

$ npm run gen-models