grams

Granular ReActive Management of State

Experimental

Description

A robust, granular, and well defined state management compatible with SOLID principles. A state manager that is reliable and consistent.

Define state once and utilize it throughout the app without much boilerplate.

Benefits:

• Atomic state
• Compatible with async actions
• Middleware compatibility
• Protected state
• Effect handling
• Structural
• No race conditions

Supported Frameworks

• React (>=16.8.0)
• React Native (>=0.59)

To install:

yarn add grams

or

npm install grams

Definitions

Gram | Name | Description | Required | Type | | --- | ----------- | -------- | ---- | | defaultValue | Default initial value of state | Y | any | | type | Type of state value | Y | "string" | "number" | "boolean" | "object" | | stateType | Type of State | N | "stateful" | "stateic" | | produce | Modifications or mutations of state | N | - | | actions | Actions to execute (can be promises) | N | - | | effects | Various effects (hooks) that run based on lifecycle | N | - | | middleware | Functions that execute before a state change | N | - |

State Types | Name | Description | | ---- | ----------- | | stateful | A type of state that will cause a rerender | | stateic | A type of state that will not cause a rerender (useful for static variables) |

Effects | Name | Description | | ---- | ----------- | | onMount | Runs after the state has been initialized. (Can be a promise and can modify the state on return) | | onUpdate | Runs after the state has been updated. Cannot modify state directly. | | onRender | Runs after the subscribed components have been rerendered. Cannot modify state directly. | | onUnMount | Runs after the state has been unmounted. Cannot modify state directly. | | onError | Runs if the state has failed. Cannot modify state directly. |

Specifications

useStore

useStore(key: string | ((stateKeys: StateKeys) => string)) => [state, setState]

A hook that accepts the key of the state, subscribes the component to the state, and returns the value of the state as well as its setter function. (Works similar to useState found in React hooks).

useStoreValue

useStoreValue(key: string | ((stateKeys: StateKeys) => string)) => state

A hook that accepts the key of the state, subscribes the component to the state and only returns its value.

useSetStore

useSetStore(key: string | ((stateKeys: StateKeys) => string)) => setState

A hook that accepts the key of the state and returns its setter function. It does not subscribe the component to the state.

useStoreProduce

useStoreProduce(produceName: string | ((stateKeys: StateKeys) => string), key: string | ((stateKeys: StateKeys) => string)) => state

A hook that accepts the name of the produce, the key of the state, subscribes the component to the state, and returns its mutated value.

useStoreActions

useStoreActions(actionName: string | ((stateKeys: StateKeys) => string), key: string | ((stateKeys: StateKeys) => string)) => setState

A hook that accepts the name of the action, the key of the state, and returns its action function. It does not subscribe the component to the state.

Usage

1. Add the Provider to the root component

...

import { Provider } from "grams";

...

root.render(
    <Provider>
      <App />
    </Provider>
);

2. Define the State

...

import { gram } from "grams";

...

const delay = (ms: number) => new Promise((resolve) => setTimeout(resolve, ms));

...

export const isAuthenticated = gram(
  false,
  "boolean",
  "stateful",
  {
    isUnAuthenticated: (currValue) => !currValue
  },
  {
    login: () => true,
    logout: () => false
  },
  {
    onMount: async (_, __, set) => {
      set(true, (storeKeys) => storeKeys.isLoading.key);
      await delay(1000);
      set(false, "isLoading");
      return true;
    }
  },
  {
    check: () => {
      console.log("auth middleware");
      return true;
    }
  }
);

3. Pass the State to the Provider

...

import { Provider } from "grams";

...

root.render(
    <Provider models={{ isAuthenticated, isLoading }}>
      <App />
    </Provider>
);

4. Subscribe to the State or use the Actions

...

import { useStoreActions, useStoreValue, useStoreProduce } from "grams";

...

const ActionComponent = () => {
  const login = useStoreActions("login", "isAuthenticated");

  return (
    <button
      onClick={() => {
        login();
      }}
    >
      Login
    </button>
  );
};

...

const ProduceComponent = () => {
  const isUnAuthenticated = useStoreProduce("isUnAuthenticated", "isAuthenticated");

  return (
    <h1>Is Unauthenticated: {String(isUnAuthenticated)}</h1>
  );
};

...

const ValueComponent = () => {
  const isAuthenticated = useStoreValue((storeKeys) => storeKeys.isAuthenticated.key);

  return (
    <h1>Is Authenticated: {String(isAuthenticated)}</h1>
  );
};

...

const Component = () => {
  const [isAuthenticated, setIsAuthenticated] = useStore((storeKeys) => storeKeys.isAuthenticated.key);

  return (
    <div>
      <h1>Is Authenticated: {String(isAuthenticated)}</h1>
      <button
        onClick={() => setIsAuthenticated(true)}
      >
        Login
      </button>
    </div>
  );
};

Caveats

• In StrictMode, the store does not function well due to limitations. For further information regarding StrictMode, visit React Docs.
  • To avoid this, the recommended approach is to add the Provider above StrictMode:

  root.render(
    <Provider models={{ isAuthenticated, isLoading }}>
      <StrictMode>
          <App />
      </StrictMode>
    </Provider>
  );

• Poor management, could lead to infinite state cycles - example listed below.

  const isAuthenticated = gram(
    false,
    "boolean",
    "stateful",
    {
      isUnAuthenticated: (currValue) => !currValue
    },
    {
      login: () => true,
      logout: () => false
    },
    {
      onMount: async (_, __, set) => {
        set(true, (storeKeys) => storeKeys.isAuthenticated.key);
        await delay(1000);
        set(false, (storeKeys) => storeKeys.isAuthenticated.key);
        return true;
      }
    },
    {
      check: () => {
        console.log("auth middleware");
        return true;
      }
    }
  );

• It could take time to setup the store. The store is created sequentially (one gram at a time) and if there are many grams defined, it could add overhead time.