Javascript Remoting with Set Collection

Question

I have a remote action method that accepts Set collection as a parameter. How do I pass a set collection from Javascript? I tried passing an array and it gave me an error message.

-------- Class -------
     @RemoteAction
     global static string forDemo(set<string> names){
         // Processing using names
         return 'go';
     }

-------- VF Page ------
    <script>

        var lstNames = new Array("Name 1", "Name 2");

        <class>.forDemo(lstNames, function(result, event){
            console.log(result);
        }, {escape: false});

    </script>

When I run the page, I get the following error in browser console

Visualforce Remoting Exception: Unable to convert parameter to Apex type: expected SET, got ArrayList

How do I pass a SET collection or can I not use it in Javascript Remoting?

Answer 1

Not sure if Javascript remoting allows sets but it does allow List<>. It looks like JavaScript does not provide a native Set data type so pasing a array of string is still considered as list than a set as per apex ( just guessing here)

public with sharing class RemotingObjectsController {    
@RemoteAction
    public static string insertAccounts(List<string> stringval){
        Map<string,string> stringMap = new Map<string,string>();
        for(string s: stringval){
        stringMap.put(s,s);
        }
        if(stringMap.Keyset() != null){
           for(string s1: stringMap.Keyset()){
             return s1;
           }
        }
return null;
    }
}

This way you can still have unique values as key is a set<> in a map

Answer 2

What you were passing is a JavaScript Array (no Set as you stated) which is why Visualforce thinks it is a List.

I wouldn't recommend this over @rao's answer, but you could declare a method that accepts a Map and get its keySet().

var aMap = {};
function addSetVal(val) {
   aMap[val] = null;
}
addSetVal('a123');
addSetVal('b456');

Visualforce.remoting.Manager.invokeAction(
  '{!$RemoteAction.RemotingController.remoteAction}',
  aMap,
  function(result, event) {
    console.log(result);
  }
);

@RemoteAction
global static void remoteAction(Map<String, String> aMap) {
  System.debug(aMap.keySet()); // {'a123','b456'}
}