react dva 碎片02

dva 是基于现有应用架构 (redux + react-router + redux-saga 等)的一层轻量封装，没有引入任何新概念，全部代码不到 100 行。( Inspired by elm and choo. )

dva 是 framework，不是 library，类似 emberjs，会很明确地告诉你每个部件应该怎么写，这对于团队而言，会更可控。另外，除了 react 和 react-dom 是 peerDependencies 以外，dva 封装了所有其他依赖。

DVA一共有5个API

import dva,{ connect } from 'dva';

// 1. Create app
const app = dva();

// 2. Add plugins (optionally)
app.use(plugin);

// 3. Register models
app.model(model);

// 4. Connect components and models
const App = connect(mapStateToProps)(Component);

// 5. Config router with Components
app.router(routes);

// 6. Start app
app.start('#root');

API

1. app = dva(opts)

新建一个dva app，你可以配置history和initialState选项。

opts.history: the history for router,default: hashHistory
opts.initialState: initialState of the app,default: {}

import { browserHistory } from 'dva/router';
const app = dva({ 
  history: browserHistory,});

2. app.use(hooks)

onError(fn): called when an effect or subscription emit an error
onAction(array|fn): called when an action is dispatched,used for registering redux middleware,support Arrayfor convenience
onStateChange(fn): called after a reducer changes the state
onReducer(fn): used for apply reducer enhancer
onEffect(fn): used for wrapping effect to add custom behavior,e.g.dva-loadingfor automatical loading state
onHmr(fn): used for hot module replacement
extraReducers(object): used for adding extra reducers,e.g.redux-formneeds extra form reducer

3. app.model(obj)

namespace：model的名称空间
state：初始state
reducers：同步的修改状态的操作，由actions触发(state,action) => state
effects：异步的操作，并不直接修改state，由actions触发，也可以调用actions。(action,{ put,call,select })
subscriptions：异步的只读操作，并不直接修改state，可以调用actions。({ dispatch,history })

put(action)和dispatch(action)
这里effects中的put(action)等同于subscriptions中的dispatch(action)，它们的作用都是分发一个action。

yield put({ type: actionType,payload: attachedData,error: errorIfHave});
dispatch({ type: actionType,error: errorIfHave});

call(asyncFunction)
调用一个异步函数

const result = yield call(api.fetch,{ page: 1 });

select(function)
从全局状态中选择数据

const count = yield select(state => state.count);

4. app.router(({ history }) => routes)

import { Router,Route } from 'dva/routes';
app.router(({ history } => ({
  <Router history={ history }>
    <Route path="/" component={App} />
  </Router>
});

5. app.start(selector?)

启动应用，selector是可选的。如果没有selector参数，它会返回一个函数，这个函数返回JSX元素。

https://github.com/dvajs/dva