I am passing a List of Maps to my controller from the client-side javascript, and when trying to access an element of this list, an internal error is thrown.

Here is an example of the problem :

Javascript :

saveData : function(component) {
    var action = component.get("c.saveDipping");

    var indexList = [];
    indexList.push(new Map());
    indexList.push(new Map());
    indexList[0].sp = 1;
    indexList[0].sp2 = 1;

        "indexListMap" : indexList
    action.setCallback(this, function(response) {
        var state = response.getState();
        if (state === "SUCCESS") {
            alert("ok !");
        } else {
            var errors = response.getError();
            alert("code : " + errors[0].message);

Apex controller :

public static void saveDipping (List<Map<String, String>> indexListMap) {


Note that the first debug works fine, and we can check the form of the list, but the second one throws the internal error.

Is there a different way to pass the list of maps as argument to make this work ?

Thank you.

  • 1
    It looks like you're trying to coerce a String into a Decimal. Have you tried adding quotes? – sfdcfox Sep 19 '18 at 12:03
  • Yes, sorry, actually this was part of a previous code where I was trying to manipulate Integer instead of String. But this wasn't the origin of the problem. But thank you ! – lonic Sep 19 '18 at 12:49

I ran into this bug on a Visualforce page a few years ago and logged a support ticket, I guess they haven't fixed it. String.valueOf still works on the List, so you may also be able to use the JSON library. You could try doing:

indexListMap = (List<Map<String, String>>)JSON.deserialize(
                JSON.serialize(indexListMap), List<Map<String, String>>.class);

Additionally, you could serialize the List to JSON in your Lightning component and pass that to the controller, then deserialize it in the controller.

  • That worked perfectly, it solved my problem, thank you very much ! It also works on different kind of maps, such as List<Map<String, Integer>>. Thanks again ! – lonic Sep 19 '18 at 12:49

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