ezcontext

A implementation of ACV (Action → Context → View) for React

Features

1. Lightweight
2. Based on new React context API
3. Support using multiple contexts at once
4. Support computed contexts
5. Support High Order Component creator

ezcontext in actions

1. Basic Functions https://codesandbox.io/s/m14qn9kyy
2. Todo App https://codesandbox.io/s/y3qlo47vxz

Samples

create(value:any, methods):Context

Create a new Context with specified value and method list. If no methods specified, ezcontext creates default wired method which named update(newState)

import { create } from "ezcontext";

const UserContext = create("guest", {
  loginAsAdmin: () => "admin",
  logout: () => "guest"
});

console.log(UserContext()); // => "guest"
UserContext.loginAsAdmin();
console.log(UserContext()); // => "admin"
UserContext.logout();
console.log(UserContext()); // => "guest"

create(value:any, methodCreator:(contextAccessor)=>Object):Context

Create a new Context with specified value and methodCreator. methodCreator retrieves contextAccessor and must return method list

import { create } from "ezcontext";

const Todos = create([], context => ({
  // load todos from server
  load() {
    // perform lazy update todos once data is loaded
    return fetch(`http://tempuri.org/todos`)
      .then(res => res.json())
      .then(todos => context(todos));
  }
}));

create(...contexts:Context[]):ComputedContext

Create a new ComputedContext which has one or many dependency Context. Once dependency contexts updated, ComputedContext will be recomputed

import { create } from "ezcontext";

const ContextA = create(1);
const ContextB = create(2);
const ContextAB = create(
  ContextA,
  ContextB,
  (aValue, bVlaue) => aValue + bValue
);

console.log(ContextAB()); // => 3

Create wired component

import { create, use } from "ezcontext";
const IdsContext = create([1, 2]);
const TodosContext = create({
  1: { text: "item 1" },
  2: { text: "item 2" }
});

const TodoList = use(
  IdsContext,
  TodosContext,
  ($ids, $todos) => ({ ids: $ids.value, todos: $todos.value }),
  props => {
    /* render todo list */
  }
);

Create an action connected with multiple contexts

import { create, use } from "ezcontext";
const IdsContext = create([1, 2]);
const TodosContext = create({});

const AddTodo = use(IdsContext, TodosContext)(text => ($ids, $todos) => {
  const id = new Date().getTime();
  $ids.add(id);
  $todos.add(id, { text });
});

AddTodo("New Todo");

Create High Order Component

import React from "react";
import { create, use } from "ezcontext";

const UserContext = create("guest");
const Authenticate = use(UserContext)(
  allowUser => $user => (Component, props) =>
    allowUser === $user.value ? (
      <Component {...props} />
    ) : (
      <div>Access denied</div>
    )
);
const AdminScreen = Authenticate("admin")(props => {
  /* render admin screen here */
});

Create HOC from context

import React from "react";
import { create, use } from "ezcontext";

const UserContext = create("guest");
const UserHoc = UserContext.hoc("username");
const UserProfile = UserHoc(props => <div>{props.username}</div>);

Create HOC from multiple contexts

import React from "react";
import { create, use } from "ezcontext";

const UserContext = create("guest");
const ThemeContext = create("default");
const DataContext = create("data");
const Hoc = use(
  UserContext.hoc("user"),
  ThemeContext.hoc("theme"),
  DataContext.hoc("data")
);
const Dashboard = Hoc(props => {
  /* render dashboard */
});