Redux Internals

Redux

Agenda

  • Redux in a nutshell

  • Middleware signature

  • Enhancing store

  • Context wormholes

Redux in a nutshell

Is Flux looks like this?

or...

Well Redux is

So Why Redux?

​

  • Separation of concerns

  • FP driven

  • Awesome developer experience

Three Principles

  • Single source of truth

  • State is changed only by emitting an action

  • Mutations described by pure functions (reducers)

The data flow

Provider

import { Provider } from 'react-redux'
import { appStore} from 'appStore'

<Provider store={ appStore }>
  <PlayerContainer/> 
</Provider>

connect(...fns)(component)

import * from 'actionCreators';
import { connect } from 'react-redux';
// ...
// ...Player React Component definition

function mapStateToProps(state){
  const { src, poster, showControls } = state.player;
  return { 
    src, poster, showControls
  }
}

export const PlayerContainer = connect(
    mapStateToProps
)(Player);

Passing around actions

import React from 'react';
import * from 'actionCreators';
import { connect } from 'react-redux';

class Player extends React.Component { 

  play(){
    this.props.dispatch(actionCreators.play())
  }

  render() {
    return (
        <PlayerWrapper>
            <PlayerSurface/>
            <PlayerControls play={this.play.bind(this}/>
        </PlayerWrapper>
    )    
  }
}

//export PlayerContainer with connect as in previous slide

mapDispatchToProps

import React from 'react';
import * from 'actionCreators';
import { connect } from 'react-redux';
import { bindActionCreators } from 'redux';

class Player extends React.Component { 

  render() {
    return (
        <PlayerWrapper>
            <PlayerSurface/>
            <PlayerControls play={this.props.actions.play} />
        </PlayerWrapper>
    )    
  }
}

function mapStateToProps(state){
//...same as previous slide
}

function mapDispatchToProps(dispatch){
  return {
    actions: bindActionCreators(actionCreators, dispatch)
  }
}


export const PlayerContainer = connect(
    mapStateToProps,
    mapDispatchToProps
)(Player);

React-Redux summary

  • Provider:  wraps root component and makes possible to use connect() 

  • connect:  executed on every state change if specified. returned object is merged into component props

  • mapStateToProps: executed on every state change if specified. returned object is merged into component props
  • mapDispatchToProps: executed on every state change, given dispatch as parameter. returned object will be injected into props. Mostly used together with bindActionCreators
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