Custom Setting list to query filter

Question

I have to create functionality to automatically add new users to a chatter group and follow it. I'm working from Bob Buzzard's example from here.

I want to have a custom setting store the group names so I can add/remove groups to auto-follow on demand without code changes so I created a list custom setting called "Chatter_Auto_Follow__c" with a custom text field called "Chatter Group".

My problem is that I cannot figure out how to query for a list of the names and then pass that into a CollaborationGroup query for the ids.

Here is a snipit that I'm working with:

// Find the group name from the custom setting
    Chatter_Auto_Follow__c setting = Chatter_Auto_Follow__c.getall().values();
    String groups = setting.Chatter_Group__c;

// Find the Chatter group Ids from the names of the custom setting
    List<CollaborationGroup> chatterGroups = [SELECT id, Name FROM CollaborationGroup WHERE Name in :groups];    

When I try to compile I get the error on my collaborationgroup query

IN operator must be used with an iterable expression

What am I doing wrong?

Answer 1

The getAll of the custom setting method returns a Map of the name to its custom setting.

You will need to iterate over them and populate a collection to include in your query:

Chatter_Auto_Follow__c[] settings = Chatter_Auto_Follow__c.getall().values();
Set<String> groups = New Set<String>();

for(Chatter_Auto_Follow__c cs : settings)
    groups.add(cs.Chatter_Group__c);

List<CollaborationGroup> chatterGroups = [SELECT id, Name FROM CollaborationGroup WHERE Name in :groups];

You could simplify it by just using the Name field of the custom setting to store the group name then you could simply do:

List<CollaborationGroup> chatterGroups = [SELECT id, Name 
  FROM CollaborationGroup 
  WHERE Name in :Chatter_Auto_Follow__c.getall().keySet()];