Task trigger creating multiple records

Question

I'm trying to override the standard log a call functionality but with some changes. When creating a log a call record it will be possible to select multiple users and multiple contacts. I've created the page with a possibility to select multiple contacts and multiple Users. But now i'm stuck with trigger.

After the user selected multiple users the id's of selected populates in a field UserListField__c (The values are devines with ,), the same is with ContactListField__c. I don't really know how to fire trigger to create multiple records based on UserListField__c.

This is what i've done for now:

trigger MultiTaskCreate on Task(before insert) {
    //Trying to Make the List of Users Id's instead of string
    List < String > UsrId = new List < String > ();
    for (Task task: trigger.new) {
        UsrId.add(task.UserListField__c);
    }
    //Creating new Tasks records
    for (Task ts: trigger.new) {
        If(UsrId != NULL) {
            Task task = new Task();
            task.Assigned_To__c = UsrId; //Using the Lists of Id's
            task.Status = 'Completed';
            task.Priority = ts.Priority;
            task.Communication_Type__c = ts.Communication_Type__c;
            task.Subject = ts.Subject;
            task.Name__c = ts.Name__c;
            insert task;
        }
    }
}

Answer 1

Here, you have to use the Split function on the string which will break the string in the set of words using the deliminator and return you a list. Try this code:

    trigger MultiTaskCreate on Task (before insert) {

Map<task, List<Id>> taskToUsersIds = new Map<task, List<Id>>();
for(Task ts: trigger.new){
    if(ts.UserListField__c != null){
            taskToUsersIds.put(ts, ts.UserListField__c.split(','));
        }
}
List<task> taskToInsert = new List<task>();
for(Task t : taskToUsersIds.keySet())
{
    for(String userId : taskToUsersIds.get(t))
    {
            Task task = new Task();
            task.Assigned_To__c = userId; //You will get the UserId here
            task.Status = 'Completed';
            task.Priority = ts.Priority;
            task.Communication_Type__c = ts.Communication_Type__c;
            task.Subject = ts.Subject;
            task.Name__c = ts.Name__c;
            taskToInsert.add(task);

    }

}
 if(taskToInsert.size() > 0)
    insert taskToInsert;
}