how to iterate through map of custom object in lightning

Question

I am trying to fetch Map in my lightning js controller.

Apex Controller:

 @AuraEnabled
public static Map<CustomObject__c, custObj__c> getQuestions(){
    Map<CustomObject__c,custObj__c> quesOpMap = new Map<CustomObject__c, custObj__c>();
    List<custObj__c> obj = [SELECT Id,Name FROM custObj__c];
    for(CustomObject__c q : [SELECT Id,Name FROM CustomObject__c] )
    {
        for(custObj__c opt : obj){
                   quesOpMap.put(q, opt);
            }
    }
    return quesOpMap;
}

JS Controller:

 var action = component.get("c.getQuestions");
    // Add callback behavior for when response is received
    action.setCallback(this, function(response) {
       var state = response.getState();
       if (state === "SUCCESS") {
            component.set("v.questions", response.getReturnValue());
        }
        else {
            console.log("Failed with states: " + state);
        } 

on loading app I am getting error as 'Unable to parse JSON Response' and if check console log for response.getReturnValue(). this is undefined.

But If I replace Map<CustomObject__c, custObj__c> with any primitive type for e.g. - Map<Id,String> or Map<String,String>, js controller is working fine.

How to get values for custom objects in lightning controller?

Answer 1

Your Map cannot be serialized to JSON, as the return values of @AuraEnabled controller methods are, because it uses an object as a key.

It's fine to return a map of a primitive to an object, like Map<String, CustomObject__c>, but you can't use a custom object as the Map key in this context.