Setting Dependent Custom Lightning Picklist Level2 and Level3 then resetting the Level2 at Lightning component but Level2 Cached Data is Getting Saved

Question

Step 1

In a Salesforce Lightning component I have a scenario with three levels of dependent picklists, first I am setting values for picklist Level1, and

Answer 1

This got fixed because I not refreshing the Level 3 picklist when the Level 1 picklist was getting changed,so added an onchange at Level3

Also copied getSelectedValue to Helper at getLvl1 function using helper.getSelectedValue(component,event,helper); (It is to be remembered one good use of helper class is this when we need some code or method to be repeatedly called,so its better to put that function in helper ) and called again at component also changed the <ui:inputSelect with new aura components like <lightning:select

Here is component

                <aura:component controller="PickListHandler" implements="force:appHostable,flexipage:availableForAllPageTypes,flexipage:availableForRecordHome,force:hasRecordId,forceCommunity:availableForAllPageTypes,force:lightningQuickAction" access="global" >
                    <!-- Actions-->
                    <aura:handler name="init" value="{!this}" action="{!c.doInit}" />
                  
                    <!-- variable-->
                    <aura:attribute name="lstLevel1" type="String[]" />
                     <aura:attribute name="lstLevel2" type="String[]"  />
                      <aura:attribute name="lstL3"  type="String[]"  />
                        <aura:attribute name="firstlevel1selected" type="String" default="" />
                     <aura:attribute name="secondlevelselected" type="String" default="" />
                      <aura:attribute name="thirdlevelselected"  type="String" default="" />
                    
                       <div class="slds-container--center slds-container--small slds-m-top--small">
                        <div class="slds-form--stacked">
                             
                            <lightning:select name="parentPicklist" label="Level 1" aura:id="ddLevel1" onchange="{!c.getLvl1}">
                                <option value="">--- None ---</option>
                                <aura:iteration items="{!v.lstLevel1}" var="value">
                                    <option value="{!value}">{!value}</option>
                                </aura:iteration>
                            </lightning:select>
                             
                            <lightning:select name="Level2Picklist" label="Level 2" aura:id="ddLevel2"  onchange="{!c.getSelectedValue}" >
                                <option value="">--- None ---</option>
                                <aura:iteration items="{!v.lstLevel2}" var="value">
                                    <option value="{!value}">{!value}</option>
                                </aura:iteration>
                            </lightning:select>
                            
                             <lightning:select name="Level3Picklist" label="Level 3" aura:id="ddLevel3" onchange="{!c.getlevel3}"  >
                                <option value="">--- None ---</option>
                                <aura:iteration items="{!v.lstL3}" var="value">
                                    <option value="{!value}">{!value}</option>
                                </aura:iteration>
                            </lightning:select>
                             
                        </div>        
                    </div>
                   <lightning:button variant="brand" label="Save" onclick="{!c.onConfirm}" />
                </aura:component>

Here is controller js

                doInit : function(component, event, helper) {
                    var action = component.get("c.getLevel1");
                    action.setCallback(this, function(e) {
                        if(e.getState()=='SUCCESS'){
                            var result=e.getReturnValue();
                            component.set("v.lstLevel1",result);
                        }
                    });
                    $A.enqueueAction(action);
                },    
                getLvl1:function(component, event, helper){
                   
                    var picklist=component.find('ddLevel1');
                    var picklistvalue=picklist.get('v.value');
                    component.set("v.firstlevel1selected",picklistvalue);
                    var action = component.get("c.getLevel2");
                    action.setParams({  'strName' : picklistvalue  });
                    action.setCallback(this, function(e) {
                        if(e.getState()=='SUCCESS'){
                            var result=e.getReturnValue();
                            component.set("v.lstLevel2",result);
                            helper.getSelectedValue(component,event,helper);
                        }
                    });
                    $A.enqueueAction(action);
                        },
                getSelectedValue:function(component, event, helper){
                    var picklist=component.find('ddLevel1');
                   
                    var picklistvalue=picklist.get('v.value');
                     
                    var picklistdep=component.find('ddLevel2');
                    
                    var picklistvaluedep2=picklistdep.get('v.value');
                    component.set("v.secondlevelselected",picklistvaluedep2);
                    var action = component.get("c.getLevel3");
                    
                    action.setParams({  'strName1' : picklistvalue,
                                     'strName2' : picklistvaluedep2});//
                    action.setCallback(this, function(e) {
                        if(e.getState()=='SUCCESS'){
                            var result=e.getReturnValue();
                            component.set("v.lstL3",result);
                        }
                    });
                    $A.enqueueAction(action);
                },
                getlevel3:function(component, event, helper){
                    var picklist=component.find('ddLevel3');
                   
                    var picklistvalue=picklist.get('v.value');
                     component.set("v.thirdlevelselected",picklistvalue);
                    
                },
                onConfirm:function(component, event, helper){
                    var picklist=component.find('ddLevel1');
                    var picklistvalue=picklist.get('v.value');
                    var picklistdep=component.find('ddLevel2');
                    var picklistvaluedep2=picklistdep.get('v.value');
                   
                    var picklistdep3=component.find('ddLevel3');
                    var picklistvaluedep3=picklistdep3.get('v.value');
                    console.log(component.get('v.firstlevel1selected'));
                     console.log(component.get('v.secondlevelselected'));
                     console.log(component.get('v.thirdlevelselected'));
                    
                    var action = component.get("c.savecasetype");
                    
                    action.setParams({  'level1' : picklistvalue,
                                      'level2' : picklistvaluedep2,
                                      'level3' : picklistvaluedep3,
                                      'id' : component.get("v.recordId")});
                                      
                    
                    var toastEvent = $A.get("e.force:showToast");
                    action.setCallback(this, function(e) {
                        if(e.getState()=='SUCCESS'){
                            var result=e.getReturnValue();
                            if(result==='successfull'){
                                toastEvent.setParams({
                                    "title": "Success!",
                                    "message": "The record has been inserted  successfully."
                                });
                                toastEvent.fire();
                            }else{
                                toastEvent.setParams({
                                    "title": "Error",
                                    "message": "The record has not been inserted  successfully."
                                });
                                toastEvent.fire();
                            }
                        }
                    });
                    $A.enqueueAction(action);
                   
                },
                   
                   
            })              

Here is helper class

            ({
                 getSelectedValue:function(component, event, helper){
                    var picklist=component.find('ddLevel1');
                   
                    var picklistvalue=picklist.get('v.value');
                     
                    var picklistdep=component.find('ddLevel2');
                    
                    var picklistvaluedep2=picklistdep.get('v.value');
                    component.set("v.secondlevelselected",picklistvaluedep2);
                    var action = component.get("c.getLevel3");
                    
                    action.setParams({  'strName1' : picklistvalue,
                                     'strName2' : picklistvaluedep2});//
                    action.setCallback(this, function(e) {
                        if(e.getState()=='SUCCESS'){
                            var result=e.getReturnValue();
                            component.set("v.lstL3",result);
                        }
                    });
                    $A.enqueueAction(action);
                },
                getlevel3:function(component, event, helper){
                    var picklist=component.find('ddLevel3');
                   
                    var picklistvalue=picklist.get('v.value');
                     component.set("v.thirdlevelselected",picklistvalue);
                    
                }
            })