Issue with LinqToDb T4 templates for a SqlLite database (using LoadSQLiteMetadata) - sqlite

Question

I'm trying to use a local SqlLite database (in my app_data) folder with LinqToDb.
Anybody an idea why LinqToDb cannot work with the following connectionstring ?
<connectionStrings>
<add name="RecyclesDB"
providerName="System.Data.SqlLite"
connectionString="data source=|DataDirectory|Recycles.sqlite3;Version=3;"
/>
</connectionStrings>
I can perfectly use this connectionstring to retrieve data the old-school way.
SQLiteConnection sqlConn;
var sqlCmd = new SQLiteCommand();
using (sqlConn = new SQLiteConnection(ConfigurationManager.ConnectionStrings["RecyclesDB"].ConnectionString))
{
sqlConn.Open();
sqlCmd.Connection = sqlConn;
/* .... */
}
However, when I try to use LinqToDB with the following t4 template it fails
<## template language="C#" debug="True" hostSpecific="True" #>
<## output extension=".generated.cs" #>
<## include file="$(ProjectDir)LinqToDB.Templates\LinqToDB.SQLite.Tools.ttinclude" #>
<## include file="$(ProjectDir)LinqToDB.Templates\PluralizationService.ttinclude" #>
<#
NamespaceName = "RecycleDashboard";
LoadSQLiteMetadata(LoadSQLiteMetadata(#"C:\inetpub\RecycleDashboard\app_data", "Recycles.sqlite3"););
GenerateModel();
#>
To specify the issue. The T4 template generates the models alright, but when I try to use these with the following code I get a null reference
using (var db = new RecyclesDB())
{
var recycles =
(from recycle in db.AppRecycles
select recycle).ToList();
}
The exception on new RecyclesDB() is :
System.NullReferenceException was unhandled by user code
HResult=-2147467261
Message=Object reference not set to an instance of an object.
Source=linq2db
StackTrace:
at LinqToDB.Data.DataConnection..ctor(String configurationString) in i:\linq2db\Source\Data\DataConnection.cs:line 41
at LinqToDB.Data.DataConnection..ctor() in i:\linq2db\Source\Data\DataConnection.cs:line 24
at RecycleDashboard.RecyclesDB..ctor() in
...
Anybody an idea what's wrong here ?

Answer 1

OK, just in case anyone else stumbles over issues with the Sqlite Dataprovider too
I resolved this but specifying my DataConnection specifically as follows
(GetDataProvider and GetConnection as suggested on https://github.com/linq2db/linq2db):
public partial class RecyclesDB : LinqToDB.Data.DataConnection
{
public RecyclesDB() : base(GetDataProvider(), GetConnection()) { }
private static IDataProvider GetDataProvider()
{
return new LinqToDB.DataProvider.SQLite.SQLiteDataProvider();
}
private static IDbConnection GetConnection()
{
return new SQLiteConnection(ConfigurationManager.ConnectionStrings["RecyclesDB"].ConnectionString);
}
}
Not sure why the code generated by the T4 template fails, but it looked like the LinqToDB DataConnection class couldn't resolve the dataprovidername 'System.Data.SQLite' automatically.