When I pass event id in to DisplayScanMembers(23), if the event_id does not appear in the database, it returns an empty set. However, apparently an empty set is equivalent a nil pointer(I guess). Therefore I cannot assign the value(nil pointer) to 'member_s' in the DisplayScanMembers function.
All I need is for the getScanMembers method to return an empty array instead nil if the database query returns a empty set.
Error that I get:
ERROR 2014/10/22 23:08:19 panic.go:29: runtime error: invalid memory address or nil pointer dereference /home/developer/gocode/src/drakecheckin/app/controllers/scan.go:236 (0x4a21f8)
func (c Scan) DisplayScanMembers(id int64) revel.Result{
if (id == -1 || id == 0){
event,_ :=c.getLatestSelectedEvent();
member_s,_ := c.getScanMembers(event.EventId);
return members;
} else {
member_s,err2 := c.getScanMembers(id);
if err2 !=nil {
event,_ :=c.getLatestSelectedEvent();
member_s,_ = c.getScanMembers(event.EventId);
}
return member_s;
}
}
func (c Scan) getScanMembers(event_id int64) (revel.Result,error) {
group_id,_ := convStrInt(c.Session["group_id"]);
org_id,_ := convStrInt(c.Session["org_id"]);;
query := "SELECT me.member_event_id,m.member_first_name,m.member_last_name,m.member_uniq_num "+
"FROM MemberEvent AS me JOIN Member AS m ON m.member_id =me.member_id AND m.org_id =me.org_id "+
"WHERE me.group_id=? AND me.org_id=? AND me.event_id=?";
members, err := c.Txn.Select(models.AllMemberEvent{}, query, group_id, org_id, event_id);
if err != nil {
return nil,err;
}
return c.RenderJson(members),nil;
}
I think your problem in "getScanMembers" function. Your return statement is revel.Result, and if you have error, you doing this:
if err != nil {
return nil, err;
}
But you should doing this:
if err != nil {
return revel.Result{}, err;
}