Hello all, 
I have a requirement in which I need to display list of account records and each account record should hold its contact records and each contact records will also have some other information in a seperate row below. 
I want to have a collapisible buttonicon on each account records and contact reocrds. when I click account record collapisible button it should show or hide its contacts, similiarly when I click on contact's collapsible icon it should show or hide some contact below it. 
This is my sample code. 
 

<aura:component implements="flexipage:availableForAllPageTypes,flexipage:availableForRecordHome,force:hasRecordId" controller="Accountcon" access="global" >
	<aura:attribute name="accounts" type="Account[]"></aura:attribute>
    <aura:handler name="init" value="{!this}" action="{!c.doInit}"></aura:handler>
    <table class="slds-table slds-table_cell-buffer slds-table_bordered">
        <tr class="slds-line-height_reset">
            <tr class="slds-truncate" ><b>Show</b></tr>
        <td class="slds-truncate" ><b>Name</b></td>               
        <td class="slds-truncate" ><b>Type</b></td>
        </tr>
        <aura:iteration items="{!v.accounts}" var="ac" indexVar="mylocIndex">
        <tr class="slds-hint-parent">
            <td> <lightning:buttonIcon value="{!mylocIndex}" iconName="{!ac.expanded?'utility:chevronright':'utility:chevrondown'}" onclick="{!c.toggle}" ></lightning:buttonIcon>
            </td>
        <td class="slds-truncate">{!ac.Name}</td>    
        <td class="slds-truncate">{!ac.Type}</td>
            </tr>
            <aura:if isTrue="{!ac.expanded}">
               <tr class="slds-line-height_reset">
                    <td class="slds-truncate" ><b>show</b></td>
            <td class="slds-truncate" ><b>Last Name</b></td>
                       
        <td class="slds-truncate" ><b>Email</b></td>
        </tr>
                    <b>Contact details</b>
            <aura:iteration items="{!ac.Contacts}" var="con">
               
               <tr class="slds-hint-parent">
                   <td> <lightning:buttonIcon value="{!mylocIndex}" iconName="{!ac.expanded?'utility:chevronright':'utility:chevrondown'}" onclick="{!c.toggle}" ></lightning:buttonIcon>
            </td>
                   <td class="slds-truncate">
                {!con.LastName}</td>
                   
                   <td class="slds-truncate">{!con.email}</td>
                </tr>
                <tr>this section should be shown or hidden onclick of collapsible button on the contact record </tr>
               </aura:iteration>
            </aura:if>
        
         </aura:iteration>
        </table>
</aura:component>




Controller.js

({
	doInit : function(component, event, helper) {
		var action = component.get("c.getacct");
        action.setCallback(this, function(action){
            component.set("v.accounts", action.getReturnValue());
        });
        $A.enqueueAction(action);
	},
     toggle :function(component, event, helper){
       
         var items = component.get("v.accounts"); 
        
        var index = event.getSource().get("v.value");
       items[index].expanded = !items[index].expanded;
       component.set("v.accounts", items);
        
        
    }
})


Apex class: 

public class AccountsController {
      @AuraEnabled
      public static List <Account> getAccounts() {
        return [SELECT Id, name, industry, Type, NumberOfEmployees, TickerSymbol, Phone, (select name, email, phone from contacts) FROM Account ORDER BY createdDate ASC limit 10];
      }
}

In my code when I click on the collapsible icon in contact it hides the entire contacts section. any help on this would be much appreciated. 
Thank you. 

I am at the part of the challenge where it asks you to Update the Flow.  
1. In the Display Text component, click into the search box above the text box and then click New Resource.

I follow the steps to create the formula
Resource Type:  Formula
API Name created_or_updated
Data Type: Text
Formula:  IF({!Create_Contact}, "created", "updated")
However, when I click done, I get the following error
I cannot figure out what I am doing incorrectly.  I am sitting on the Display Text in the Confirm Screen.
Thank you.