1] Create a push topic where push notifications would be created once new records are inserted in select SObject.
PushTopic pushTopic = new PushTopic();
pushTopic.Name = 'PopUpAPIUpdates';
pushTopic.Query = 'Select Id,other fields from '+ 'SObject';
pushTopic.ApiVersion = 48.0;
pushTopic.NotifyForOperationCreate = true;
pushTopic.NotifyForOperationUpdate = false;
pushTopic.NotifyForOperationUndelete = false;
pushTopic.NotifyForOperationDelete = false;
pushTopic.NotifyForFields = 'Select';
insert pushTopic;
2] Place following line in Parent Aura component which wants to handle platform events.
<c:EmpApiSubscribe channelName="/topic/PopUpAPIUpdates" onEmpEvent="{!c.handleMessage}" />
3] Place following content in EmpApiSubscribe component
<aura:component access="global">
<!-- ChannelName, which needs to subscribed -->
<aura:attribute name="channelName" type="String" required="true"/>
<!-- Save the reference of current subscription, which can be unsubscribe later on -->
<aura:attribute name="subscription" type="Object"/>
<!-- This event is fired when a component is destroyed.
Handle this event if you need to do custom cleanup when a component is destroyed.-->
<aura:handler name="destroy" value="{!this}" action="{!c.unsubscribe}"/>
<!-- init event -->
<aura:handler name="init" value="{!this}" action="{!c.subscribe}"/>
<!-- empApi component which will be used to subscribe/unsubscribe to a channel -->
<lightning:empApi aura:id="empApi"/>
<!-- Component event, which will be fired once the message is received
This event will be handled by parent component to perform needful action on stream event -->
<aura:registerEvent name="onEmpEvent" type="c:EmpEvent"/>
</aura:component>
4] EmpApiSubscribe front end controller.
({
subscribe: function(component, event, helper) {
// Get the empApi component.
var empApi = component.find("empApi");
// Get the channel name from attribute
var channel = component.get("v.channelName");
//fetch latest events
var replayId = -1;
// Callback function to be passed in the subscribe call.
// After an event is received, this callback fire a custom
// event to notify parent component and pass payload object
var subscribeCallback = function (message) {
console.log('message.data'+message.data);
//Fire the component event to notify parent component
var messageEvent = component.getEvent("onEmpEvent");
if(messageEvent!=null) {
messageEvent.setParam("empData", message.data);
messageEvent.fire();
}
//Display event data in browser console
console.log("Received [" + message.channel +
" : " + message.data.event.replayId + "] payload=" +
JSON.stringify(message.data.payload));
}.bind(this);
// Register error listener and pass in the error handler function.
empApi.onError(function(error){
console.log("Received error1 ", JSON.stringify(error));
}.bind(this));
// Subscribe to the channel and save the returned subscription object.
empApi.subscribe(channel, replayId, subscribeCallback).then(function(value) {
console.log("Subscribed to channel " + channel);
component.set("v.subscription", value);
});
},
/**
* This function will be fired once the component is destroyed
* It will call unsubscribe method of empApi component
* @version 1.0.0
* */
unsubscribe : function (component, event, helper) {
// Get the empApi component.
var empApi = component.find("empApi");
// Get the channel name from attribute
var channel = component.get("v.channelName");
// Callback function to be passed in the unsubscribe call.
var unsubscribeCallback = function (message) {
console.log("Unsubscribed from channel " + channel);
}.bind(this);
// Error handler function that prints the error to the console.
var errorHandler = function (message) {
console.log("Received error2 ", message);
}.bind(this);
// Object that contains subscription attributes used to
// unsubscribe.
var subscription = {"id": component.get("v.subscription")["id"],
"channel": component.get("v.subscription")["channel"]};
// Register error listener and pass in the error handler function.
empApi.onError(function (error) {
console.log("Received error ", error);
}.bind(this));
// Unsubscribe from the channel using the sub object.
empApi.unsubscribe(subscription, unsubscribeCallback);
},
})
5] In front end controller of parent aura component
handleMessage : function(component, event, helper) {
const param = event.getParam('empData'); //made changes here 'message'
//Invoke business logic api method and pass to it attributes of param.sobject
});
$A.enqueueAction(action);
}
