[SalesForce] Selected value in picklist

This is a known issue in the Framework.

We do plan to fix it, but there is a workaround and so it's not #1 on our plate over things like Performance.

Short Story

<aura:renderIf isTrue="{!v.testingArray.length > 0}">
        <SPAN>
        <aura:iteration items="{!v.testingArray}" var="opp">
            {!opp.name} <br/>
        </aura:iteration>
        </SPAN>
        <aura:set attribute="else">
            Array empty
        </aura:set>
    </aura:renderIf>

Long Story

The issue here is that some components like aura:renderIf and aura:iteration may not actually render anything. But you can come along later, change a condition and then they render.

To know where to render when it comes time to do so, we add a comment into the page. Then when we have some output, we replace the comment with the output.

But when you get a component like iteration which uses a comment, inside another component that uses a comment the framework gets confused. We replace the comment with the content of the iteration, but then renderIf loses its marker comment and you've hit the error.

Wrapping the iteration in a span causes iteration and renderIf not to share markers and things start working again.

Something we plan to fix, but the marker system is so complex we have to be careful not to break other things.

After looking at all the code you sent me, I am pretty sure the problem you are encountering is the same as the one reported here, which appears to be a Framework issue yet to be resolved.

That said, I have a better workaround than the one one suggested in that post. The problem seems to happen when the call returns an empty array such as what would happen for those items marked non-completed. But, it occurred to me that you might want to re-consider how you are getting the data and instead of returning all the data in each doInit and then using the aura:if to only display what you want. Instead you can resolve this (and I verified it worked by the way), by simply changing your code to pass the completed flag to the getWhiteboardItemsDB method in your Apex class and only return the data you actually want.

This would involve changing the code in your Apex Controller to look like the following:

public with sharing class ListWhiteboardItemsApexController {

@AuraEnabled
public static List<Whiteboard_Item__c> getWhiteboardItemsDB(Boolean completed) {
    return [SELECT Id, OwnerId, IsDeleted, Name, CreatedDate, LastModifiedDate, CreatedById, LastModifiedById, SystemModstamp, 
            AssignedTo__c, Completed__c, CompletedBy__c, Completed_Date__c, High_Priority__c, Display__c, Item_Due_Date__c
            FROM Whiteboard_Item__c
           WHERE Completed__c =: completed];
}
 }

And also change the code in the helper function that calls this method to look like the following:

 getWhiteboardItems : function(component) {
    var action = component.get('c.getWhiteboardItemsDB');
    var completed = component.get('v.completed');
    action.setParams({ "completed" : completed});
    action.setCallback(this, function(response) {
        var state = response.getState();
        if(component.isValid() && state == "SUCCESS") {
            component.set("v.whiteboardItems", response.getReturnValue());
        }
    });
    $A.enqueueAction(action);
}

You can then leave your code in the ListItems component with the aura:if and it should work without getting the error.

Please let me know if you think this would work and if so, mark this as the answer so it can possibly help other people.