UnCircled

A simple-yet-powerful library for implementing, serializing and deserializing the root-store pattern.

• Also supports a nested root-store pattern.
• Prevents circular reference/max-stack errors when serializing/deserializing class objects.
• Great for implementing a mobx root-store tree hydrated over SSR e.g Next.JS
• Built with Typescript.

Why I built this

I have been looking for the best way to easily use mobx with Next.JS (and server side rendering in general) and I kept running into circular reference errors when trying to hydrate my store from server side to client side for SSR.

• I didn't want to switch to mobx-state-tree because:
  • it has performance issues as of the time of this writing, and it doesn't seem like it will be solved.
  • I rather not be forced to follow an opinionated pattern.
  • I prefer the store-tree / root-class pattern from raw mobx over the mst pattern as it is more cognitive and concise.
• I tried nextjs-mobx-wrapper but it does absolutely nothing to handle the serialization and deserialization of your mobx stores (talkless of a store tree pattern) down the wire, so I'm still confused as to what the point of that library is.

I seemed to be going around in circles so, as is my tendency, I decided to create a helpful library that uncircled myself and my stores. Hope it solves your SSR issues as well.

To install

npm i uncircled

Introduction

Uncircled exports 3 things: 2 decorators and 1 abstract class.

• Deserializer: A class Decorator. injects the deserialize function into any class. You want this on your root store.
• @ParentField: A field Decorator. Put this in front of a field that links to a parent object. Important for preventing circular errors.
• @DateField: A field Decorator. Put this in front of a date field for better marshalling. The date field is the only primitive field not natively supported by the JSON schema.

How to Use

Consider these classes...

import {DateField, ParentField, Deserializer} from 'uncircled';

@Deserializer
class RootStore {
    foo = 'bar';
    childStore: ChildStore;

    constructor() {
        super();
        this.childStore = new ChildStore(this);
    }

    // For typescript's sake, define an empty deserialize function so it knows 
    // that this function that is injected by @Deserializer exists. Future versions of Typescript will allow for smarter
    // detection of decorator injections. Or you can leave this out and simply @ts-suppress each ts warning about store.deserialize not existing.
    deserialize(rawObject: string | any) {
    }
}

// The following classes need not be in the same file. You can export them into your root class.

class ChildStore {
    ab = 'wonton';
    @DateField myDate = new Date(1000000);
    @ParentField parent: RootStore;

    child: NestedLeafStore;

    constructor(parentNode: RootStore) {
        this.parent = parentNode;
        this.child = new NestedLeafStore(this);
    }
}

class NestedLeafStore {
    mn = 'Fiery';
    op = 'jutsu';
    @ParentField parent: ChildStore;

    constructor(parentNode: ChildStore) {
        this.parent = parentNode;
    }
}

// initialize the whole store tree.
const store = new RootStore();

The Root-store pattern is a declarative tree of classes that each know their parents, contents and children. This is the reccomended way of using some state management libraries like MOBX.

Serializing

Any of the field decorators you use in a class, injects that class with a special toJSON() function that eliminates circulars (assuming you used the proper field decorators0) which is used by javascript to automatically serialize any object or to stringify it you call JSON.stringify.

We can take our entire store tree implementation from the root and serialize it for transmission i.e turn to string. If you were using this with mobx and SSR, you would do this server side

const str = JSON.stringify(store);

str is now the string representation of your entire store tree.

Deserializing

Remember that @Deserialize decorator? Well it injected a member function into your root class called deserialize(stringOrObject). It can accept a json string or a fully json parsed javascript object. Either works!

Assuming you have passed in that str from the server to the client, you can do this client-side to hydrate the contents of the store tree to as it existed in the server.

store.deserialize(strFromServer);

And that's it!

Now your client-side store has been fully hydrated and all values will be the same as you had them in the server.