Entity Framework object reference not set when getting data from table

Question

command = "INSERT INTO clients VALUES(" + NameTB.Text +")";
objCtx.SaveChanges();

List<Client> clients = new List<Client>();
clients = objCtx.ExecuteStoreQuery<Client>("Select * from clients").ToList();

string x = "";
for (int i = 0; i < clients.Count; i++)
     x += clients[i].Name.ToString();//exception here

MessageBox.Show(x);

I just start to work with EF and have no idea how to fix this; I took the code from here

Warning !!! SQL Injection – Akash Kava Apr 24 '14 at 11:22 — Akash Kava, Apr 24 '14 at 11:22

Omri Aharon · Answer 1 · 2014-04-24T11:26:38.600

2

Sounds like the Name property is null in the Client data that is returned.

Either have a constraint in the database that this field is required or add a null check:

string x = "";
for (int i = 0; i < clients.Count; i++) {
     if (!String.IsNullOrEmpty(clients[i].Name)) {
          x += clients[i].Name.ToString();
     }
}

Also, if you're going to work with many clients and your string is going to get big I suggest you take a look at StringBuilder.

edited Apr 24 '14 at 11:26

answered Apr 24 '14 at 11:19

Omri Aharon

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how do I add a constraint in the database? – Mihai Bratulescu Apr 24 '14 at 12:52
@MihaiBratulescu Which database are you working with? – Omri Aharon Apr 24 '14 at 13:36
mdf, is that what you are asking for? – Mihai Bratulescu Apr 24 '14 at 13:46
@MihaiBratulescu Isn't that SQL or something ? take a look here http://stackoverflow.com/questions/689746/altering-a-column-null-to-not-null – Omri Aharon Apr 24 '14 at 13:57
I just noticed I forgot to execute the SQL command so there is no data in the table so my question now is why is the length on the list 3 and not 0? – Mihai Bratulescu Apr 24 '14 at 14:13
@MihaiBratulescu Don't know, I can't see your list :) If it's 0 length before the query and 3 after then something does come back. – Omri Aharon Apr 24 '14 at 14:18
all list entries are null and no INSERT query was ever executed, I'm not at work anymore but thanks for your time – Mihai Bratulescu Apr 24 '14 at 14:20

Entity Framework object reference not set when getting data from table

1 Answers1