LOCATION BASED MOBILE MESSAGING APP TO ASK FOR HELP
React-Native Redux SendBird Firebase
location
authentication using Google+
client side state in Redux store
persistent data store in Firebase
Firebase pushes update events to client, trigger Redux store to update
chatroom
invite friends to Chatroom
push notification
helpers can reply to help request, opening custom chatroom
add and invite friends network
##GETTING STARTED Run npm install from the root folder of the project. npm start will start the server, and react-native run-ios will run the app in your iOS simulator. For more information check Facebook's official documentation at https://facebook.github.io/react-native/docs/getting-started.html.
This app manages all its client side state using Redux. This means that none of the React components hold their own state, and instead are just pure functions which take props and return as JSX view.
As much as possible components are written as stateless functional components instead of React Component classes.
Files relating to Redux are located in the following directories:
| app/ | actions/ | reducers/ store.js
The app/store.js file creates an instance of a Redux store using the reducer exported from app/reducers/rootReducer. This Redux store instance is exported and used in index.ios.js to expose the Redux store to all the React components using the component from the react-redux library.
The Redux store sometimes makes use of Immutable, a library which makes variables that cannot be mutated. To update state, you have to create a new Immutable object rather than mutating the old version.
While most Redux examples use plain JS objects and try to prevent mutation of state using convention, Immutable enforces not mutating state.
We mostly use Immutable Lists (which are arrays that you can't change) and Maps (which are objects you can't change)
To get the value of a property of a map is is Map.get('key') as opposed to Object['key'] for a regular JS object.
In Redux, state is never mutated directly. When state needs to be updated, you can dispatch an action using store.dispach. The store will then call the appropriate reducer method to update state.
All ways that you can update state are located in app/actions/actionTypes.js. This file just exports strings that are the action types that the reducers will compare against when deciding how to update state.
The other files in actions are all action creators which take an input and return a Redux action object.
A Redux action object is a plain JavaScript object with the a type property.
An example of a Redux action would be:
{
type: 'UPDATE_USERS',
users: [{UserObject}, {UserObject}]
}Each Redux action has a type property telling the store which reducer to user, most actions have a payload, which the reducer uses to update the state. In the above example, the payload is stored in the action's user property.
A reducer is a pure function that takes a state object and an action object as inputs and returns a new state.
In the app/reducers directory you will find various reducers which each manage a portion of the application's state. For example the userReducer manages the state of the applications current user. The locationReducer manages the state of the application's current location, taken from the phone's GPS. These child reducers are combined into a rootReducer in app/reducers/rootReducer which manages the entire state of the app.
This rootReducer function is used to instantiate the Redux store in app/store.js.
This application uses the react-redux library which provides the useful component and connect function to wire together the Redux store with React components.
At an abstract level, React components will not access state directly. Instead they will have state injected, using the container pattern.
Put a different way the React components will not have a this.state but will instead have any data they need to render passed in as a prop.
To wire React and Redux together you need to have the following:
-
A Provider component that wraps your top level app component
-
A container for each stateful component, i.e. a container that needs to display and update the applications state
-
functions that map the specific state that a component needs to props that will be passed into the component.
In the root directory, the index.ios.js file shows the Provider component wrapping the NavRootContainer, which is the top level component of the application.
The Provider has a prop called store, which is set to the Redux store instantiated in app/store.js.
Because the Provider component wraps the top level component of the app, all components now have access to the state stored in the Redux store.
Containers provide the specific API for React components to interact with state. Using containers you can decide which pieces of state you will pass into you React components as props, and which ways you will allow your React components to update state, which component located in app/components/SignIn as an example, let's walk though how we will provide SignIn the data it needs using a container.
Looking at SignIn.js, we see the SignIn component needs to check whether the current user is signed in (i.e. on line 28 where it check's whether the current user's name is 'Guest'). Addtionally, the SignIn container will display the user's name, email and profile picture if the user is logged in.
So the SignIn component needs to have knowledge of the state's Current User.
We will pass the current user as a prop into the SignIn component using the SignInContainer in app/containers/SignInContainer.
In SignInContainer, we import the connect function from the react-redux library.
Then we have to define 2 functions.
mapStateToProps returns a object where the user property is mapped the where the Current User is stored in the state (state.userState). This is also the name of the reducer that manages userState.
The user will now be available inside the SignIn component as this.props.user.
mapDispatchToProps takes the store's dispatch method as an argument and returns an object containing all the functions the SignIn component will need to call to update state. We know when a user signs, we will have to update the UserState in the Redux store. So we pass in two functions to the SignIn component: updateUser, and removeUser. Both of the functions dispatch an action to the Redux store, to update state. These functions can be accessed within the SignIn component using this.props.updateUser and this.props.removeUser.
Lastly we use the react-redux connect function to ties both mapStateToProps and mapDispatchToProps to the SignIn component and save the value returned in a variable called SignInContainer container and export that value.
The important thing now is when we want to render the SignIn component, instead we have to call the SignInContainer, which is just the SignIn component with the user state injected in.
-Become a Redux ninja with the 2 hour course taught by Dan Abramov, creator of Redux: https://egghead.io/courses/getting-started-with-redux
- This simple GitHub project shows how to structure a React Native/ Redux project by seperating actions, reducers, components and containers. https://github.com/bruz/react-native-redux-groceries