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I am trying to grab a list of unique users from a subset of leads and I am running into a System.QueryException: List has no rows for assignment to SObject error.

Here is my new code below. If I get an exception in the for loop will it still continue executing?

Set<User> usr = new Set<User>();

for(Lead led : lst) {
        try {
            User lusr = [SELECT Email, Name from User where Id = :led.OwnerId LIMIT 1];
            if(!usr.contains(lusr)) {
                usr.add(lusr);
            }
        } catch(Exception e) {
            System.debug('**Exception: ' + e.getMessage());
        }
    }

Thanks for the help! This is for a scheduled Apex job.

4

Yes, but you should not put a query in a loop. This may run in governor limits. Instead, collect all the OwnerId values first, then query them:

Map<Id, User> owners = new Map<Id, User>();
for(Lead led: lst) {
  owners.put(led.OwnerId, null);
}
owners.putAll([select email, name from user where id = :owners.keyset()]);
for(Lead led: lst) {
  User u = owners.get(led.OwnerId);
  if(u != null) {
    ...
  }
}

This is what I commonly call the "Aggregate-Query-Update" pattern, since you aggregate (gather together) values, perform a single query, then do some sort of post-query update.

Also note that by using this pattern, you can often avoid QueryException ("no rows for assignment") and other similar errors. In general, you should not use try-catch unless you absolutely need to, because it has a serious implication on CPU governor limits.

  • Thanks! Implementing this now. I was running into errors from some OwnerIds not being users in our system. I really appreciate the explanation too. – Patrick Fedigan Jan 17 '18 at 17:58
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Even if an exception is thrown for a single record the loop will continue fetching the other records.

Attention! you are having an SOQL query inside a for loop which is not a best practice (take a look here)

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