@mitter-io/react-scl

Mitter.io SCL (React)

The standard component library for ReactJS applications.

react-scl

• Function of the package

This package is used for only for front-end UI in the web. Currently there are two components in this package MessageList and MessageWindow. Both components are powered by react-virtualized and is used for managing large message lists efficiently.

MessageListManager uses MessageList to manage messages and MessageListManager is the component that is exposed to the user

MessageWindowManager uses MessageWindow to manage messages and MessageWindowManager is the component that is exposed to the user

Currently MessageListManager is deprecated , please use MessageWindowManager for finer control.

The props for both of these components are listed below:

Props for MessageListManager

props	types
messages	ChannelReferencingMessage[]
onComponentMount?	() => void
onComponentUpdate?	(currentProps: object, prevProps: object) => void
producers	Producer[]
defaultView	(item: ChannelReferencingMessage) => ReactElement. A Default Component if none of the producers produce a view
onEndCallback	() => void. Callback which gets called when the scroll bar reaches the top.
loader	() => ReactElement. A spinner component to show the user when the messages are being fetched
isLoading	boolean. To inform the component if the message fetching call is in flight. This tells the component to show the loader
scrollToIndex?	number

Props for MessageList

props	types
messages	ChannelReferencingMessage[]
onEndCallback	() => void. Callback which gets called when the scroll bar reaches the top.
getViewFromProducer	(item: ChannelReferencingMessage) => ReactElement
loader	() => ReactElement. A spinner component to show the user when the messages are being fetched
isLoading	boolean. To inform the component if the message fetching call is in flight. This tells the component to show the loader
scrollToIndex?	number

Props for MessageWindowManager

props	types
channelId	string
messages	ChannelReferencingMessage[]
producers	(item: ChannelReferencingMessage) => ReactElement
fetchNewerMessages	(channelId: string, after?: string) => Promise<ChannelReferencingMessage[]>
fetchOlderMessages	channelId: string, before?: string) => Promise<ChannelReferencingMessage[]>
minRowHeight	number
loader	ReactElement
fetchThreshold?	number
fixedHeight?	boolean
mitter?	Mitter
newMessagePayloadHook?	(message: ChannelReferencingMessage) => ChannelReferencingMessage
scrollIndicator?	(unreadCount: number, onClick: () => void) => ReactElement

Props for MessageWindow

props	types
initialMessages	ChannelReferencingMessage[]
getViewFromProducer	(item: ChannelReferencingMessage) => ReactElement
fetchNewerMessages	(channelId: string, after?: string) => Promise<ChannelReferencingMessage[]>
fetchOlderMessages	channelId: string, before?: string) => Promise<ChannelReferencingMessage[]>
minRowHeight	number
loader	ReactElement
fetchThreshold?	number
fixedHeight	boolean
scrollIndicator?	(unreadCount: number, onClick: () => void) => ReactElement

MessageListManager

MessageListManager is the component exposed to the user. It uses MessageList to manager messages and MessageList internally uses React-Virtualized. The props taken by the component is given above

MessageList

MessageList internally uses React-Virtualized. Please go through the API docs of React-Virtualized before going through this component. The props taken by this component is given above.

An example of this implementation is at
https://github.com/mitterio/mitter-web-starter/tree/with-scl

MessageWindowManager

MessageWindowManager is the component exposed to the user. It is complete different implementation of the MessageListManager.

MessageWindow

On Fist Load of the component

This component takes in an initial set of messages(if the user has saved some messages in his local storage or any storage) and makes a call to get messages after the given set of messages from the user or makes a call to get the latest set if the user has not provided any initial set

The component keeps fetching for messages till a scroll appears so that the window is scrollable. If the total number of messages in the channel fits in the window, the call returns an empty array the component terminates the fetching process and sets fetchTillScrollable to false

On Scroll To Top and Scroll To End Callbacks are triggered when the user scrolls to both end. Scrolling to top triggers a fetchOlderMessages call and scrolling to the bottom triggers a fetchNewerMessages call.

Deduping messages This component does perform a deduping operation on the initial messages that are given by the user and on the messages given by fetchOlderMessages and fetchNewerMessages

Reason for taking channelId as a prop In a web.whatsapp style layout where the chat list is on the left side and the active chat is on the right side of the screen, passing the active channel Id to the component unmounts the MessageWindow and loads a new instance of the MessageWindow with new messages

An example implementation of this component is given below

 <div style={{flex: 1, backgroundColor: '#f5f5f5'}}>
                    <MessageWindowManager
                        ref={this.msgManagerRef}
                        messages={this.props.queriedMessages || []} // initial messages from state containers ( redux or mobx) or from local storage
                        producers={[this.messageViewProducer]} // producers
                        defaultView={(message) => {
                            return <div
                                style={{'borderTop': '1px solid black'}}>{message.textPayload}</div>
                        }}
                        fetchNewerMessages = {this.fetchNewerMessages}
                        fetchOlderMessages = {this.fetchOlderMessages}
                        loader={<LoaderForMsgFetch/>}
                        channelId = {this.queriedRandomChannelId}
                        minRowHeight={141}
                        fixedHeight={false}
                        newMessagePayloadHook = {channelReferencingMessageDecoder}
                        scrollIndicator={ScrollIndicator()}
                    />
                </div>
            </div>

• Message View Producer Sample

 this.messageViewProducer = createMessageViewProducer(
            (_message) => true,
            (message) => {
                return (
                    <MessageBubble
                        message={message}
                        key={message.messageId}
                        showChannelInfo={true}
                    />
                )
            }
        )

 fetchNewerMessages = (channelId: string, after?: string) => {
         
         /** SEND INFLIGHT HERE IF REQUIRED */
         if (after) {
             this.msgPaginationManager.after = after
         }
         
         return this.msgPaginationManager.nextPage()
             .then(messages => {
                 return messages
             })
             .catch(() => {
                 return []
             })
 
     }
     fetchOlderMessages = (channelId: string, before?: string) => {
         
         /** SEND INFLIGHT HERE IF REQUIRED */
         if (before) {
             this.msgPaginationManager.before = before
         }
         
         return this.msgPaginationManager.prevPage()
             .then(messages => {
                 const messageListClone = messages.slice()
                 return messages.reverse()
             })
             .catch(() => {
                 return []
             })
     }

• example of a scroll indicator

import React from 'react'

type Props = {
    unReadCount : number
    onClick: () => void
}

class ScrollHelper extends React.Component<Props> {
    constructor(props){
        super(props)
    }

    onClickScrollIndicator = () => {
        if(this.props.onClick) {
            this.props.onClick()
        }
    }

    render() {
        return(
            <div className= "mitter-scroll-indicator-container" onClick={this.onClickScrollIndicator}>
                <div className= "mitter-scroll-indicator">
                    {
                        this.props.unReadCount  > 0 &&
                        <div className= "mitter-count-indicator">
                            {this.props.unReadCount}
                        </div>
                    }

                    <i className="material-icons mitter-down-arrow-indicator" >keyboard_arrow_down</i>
                    <i className="material-icons mitter-down-arrow-indicator">keyboard_arrow_down</i>
                </div>
            </div>
        )
    }

}


export default function ScrollIndicator() {
    return (unreadCount: number, onClick: () => void) => {
        return <ScrollHelper unReadCount={unreadCount} onClick={onClick}/>
    }
}

• example of new messagePayload hook

export const channelReferencingMessageToLowerCase = (message: ChannelReferencingMessage): ChannelReferencingMessage => {
    message.textPayload = message.textPayload.toLowerCase() 
    return message
}