Hello,
I have created an aura component to allow client to follow /subscribe to an article.
When a user click on the button subscribe, a record is created in Salesforce
.
Until there the code behaves as expected.
The problem is when the user has subscribed, he needs to be able to unsubscribe by click on the same button
But when clicking the button I am not able to unsubscribe, the button remains to subscribed
Even worst, anytime I click the button, a new record is created in salesforce.
The idea is to stop the client for subscribing more than once to the same article and be able to unsubscribe when clicking on the button

here is my code:
KnownErrorSubscription.comp

<aura:component controller="KnownErrorSubscriptionController" implements="forceCommunity:availableForAllPageTypes,flexipage:availableForAllPageTypes,force:hasRecordId" access="global">

<aura:attribute name="recordId" type="String"/>
    <aura:attribute name="isFollowed" type="Boolean" default="false"/>
    <aura:handler name="init" value="{!this}" action="{!c.doInit}"/>
    
    <lightning:buttonStateful
        labelWhenOff="Subscribe"
        labelWhenOn="Subscribed"
        labelWhenHover="Unsubscribe"
        iconNameWhenOff="utility:add"
        iconNameWhenOn="utility:check"
        iconNameWhenHover="utility:close"
        state="{! v.isFollowed }"
        onclick="{! c.handleClick }"/>
	
</aura:component>

KnownErrorSubscriptionController.js
 

({
       doInit: function(component, event, helper) {
             let search = window.location.pathname;
             let result = search.substring(search.lastIndexOf("/") + 1);
             let action = component.get("c.isRecordExist");

             action.setParams({
                     urlNames : result
              });
              action.setCallback(this, function(data) {
                    let result = data.getReturnValue();
                     if(result){
                         component.set('v.isFollowed', 'true');
                      }
             });
             $A.enqueueAction(action);
         },

         handleClick : function(component, event, helper) {

              let search = window.location.pathname;
              let result = search.substring(search.lastIndexOf("/") + 1);
              let action = component.get("c.saveKnownIssue");
              
             action.setParams({
                  urlNames : result
             });

             action.setCallback(this, function(data) {
                  let result = data.getReturnValue();
                  if(result){
                        component.set('v.isFollowed', 'true');
                    }
              });
             $A.enqueueAction(action);
       }
})

KnownErrorSubscriptionController.apxc
 

public class KnownErrorSubscriptionController {
    
    @AuraEnabled
    public static Boolean isRecordExist(String urlNames) {
        List<User> userList = [SELECT Id, Name, ContactId, Contact.Name FROM User WHERE Id = :UserInfo.getUserId()];
        List<Knowledge__kav> kavList = new List<Knowledge__kav>();
        if(urlNames != null) {
            kavList = [SELECT Id, LastPublishedDate, Title, ArticleBody__c FROM Knowledge__kav WHERE UrlName =:urlNames];
        }
        
        if(userList.size() > 0 && kavList.size() > 0) {
        	List<Known_Error_Subscription__c> kESubscriptionList = [SELECT Contact__c, Knowledge__c FROM Known_Error_Subscription__c
                                                                    WHERE Contact__c =:userList[0].ContactId AND Knowledge__c =:kavList[0].Id];
            if(kESubscriptionList.size() > 0) {
            	return true;
            } else {
            	return false;
            }
                
        } else {
        	return false;
        }        
    } 
    
    @AuraEnabled
    public static Boolean saveKnownIssue(String urlNames, Boolean isFollowed) {
        List<User> userList = [SELECT Id, Name, ContactId, Contact.Name FROM User WHERE Id =:UserInfo.getUserId()];
        List<Knowledge__kav> kavList = new List<Knowledge__kav>();
        
        if(urlNames != null) {
            kavList = [SELECT Id, LastPublishedDate, Title, ArticleBody__c FROM Knowledge__kav WHERE UrlName =:urlNames];
        }
        Known_Error_Subscription__c kes = new Known_Error_Subscription__c();
        if(userList.size() > 0 && userList[0].ContactId != null) {
            kes.Contact__c = userList[0].ContactId;
        }
        
        if(kavList.size() > 0) {
            kes.Knowledge__c = kavList[0].Id;
            kes.Subscribed__c = true;
        }
        
        insert kes;
        return true;
        
    }
    

}