I am using Sqlite and Dapper. I need to bypass an exception error and return an empty row when there are no records in the Table or the Database File or Table does not exist.

Question

I am using Sqlite and Dapper. I need to bypass an exception error and return an empty row when there are no records in the Table or the Database File or Table does not exist.

Ronald Rex 1,666

Hi all Friends,

I am returning rows from a Sqlite/Dapper transaction. And if I run into an exception instead of the application crashing, I would like to return an empty row. Thanks !

2 answers

Your answer

Answer 1

Johan Smarius 470 MVP

You can wrap your call in a try/catch block and in the catch block return an empty row.

Ronald Rex 1,666 Reputation points

2023-09-07T13:33:35.8866667+00:00
I am trying to use this code to add an empty row as was suggested in a comment. I am getting a compiler error cannot convert from ModelLibrary.PayerModel to 'T'. Why am I getting this compiler error? Thanks !!!

List<T> rows=new List<T>(); rows.Add(new PayerModel {LastUser="No Records", AccessDate="", DirName="", PayerName="", Id=1, Reminder=""}); return rows;

Answer 2

Karen Payne MVP 35,586 Volunteer Moderator

All these are from me doing simple Google searches

Database exists

if(File.Exists("database.db"))

Table exists

SELECT name FROM sqlite_master WHERE type='table' AND name='{table_name}';

Can not repy to empty row unless I see your C# code.

Ronald Rex 1,666 Reputation points

2023-09-07T16:08:17.17+00:00

Give me a sec please. Thanks !!!
Ronald Rex 1,666 Reputation points

2023-09-07T17:01:59.66+00:00
@Karen Payne MVP All that I want to do is rewrite this procedure as the commenter suggested in a try catch statement block and if the catch statement is executed I want to return 1 row with a field that has text "No records found". I have done this before with SQl statements in my code, but there may be factors such as this is using a Delegate, or Dapper but the compiler Error is saying that it cant convert from 'Model' to 'T'. Thanks !

public List<T> GetData<T, U>(string sqlStatement, U parameters, string strConnection) { try { using IDbConnection connection = new SQLiteConnection(strConnection); List<T> rows=connection.Query<T>(sqlStatement, parameters).ToList(); return rows; } catch (Exception ex) { return row "No records found"; }
Ronald Rex 1,666 Reputation points

2023-09-07T19:07:09.48+00:00

@Karen Payne MVP Your recommendations are entirely logical but the requirements are that I return an empty row so that my listview will load. Maybe I can set that somewhere in the Xaml or maybe the listview as a default setting when it doesnt have any rows. But again the requirements would like to see the code hit the exception.
Karen Payne MVP 35,586 Reputation points Volunteer Moderator

2023-09-07T21:58:41.5666667+00:00

I've not worked very much with Dapper so no joy there (gave up on it with super complex statements and will be working with the author soon on this).

In regards to try/catch should be the last resort and are in some cases considered the easy way out.

I wonder if you might consider running a SELECT COUNT first to see if the current statement would have any records?

Now with that mentioned using a non-generic method simply test for any results, in this case there are none as PhoneTypeIdentifier has no 38, stops at 10.

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I am using Sqlite and Dapper. I need to bypass an exception error and return an empty row when there are no records in the Table or the Database File or Table does not exist.

2 answers

Your answer