https://github.com/linq2db/linq2db.LINQPad/pull/102

Author: MaceWindu

Source/Drivers/DriverHelper.cs

@@ -99,17 +99,26 @@ public static MappingSchema InitializeContext(IConnectionInfo cxInfo, IDataConte
 			// apply context-specific Linq To DB options
 			Common.Configuration.Linq.OptimizeJoins = settings.LinqToDB.OptimizeJoins;
 
+			// TODO: add OnTraceConnection to IDataContext
 			if (context is DataConnection dc)
-			{
 				dc.OnTraceConnection = GetSqlLogAction(executionManager);
-				DataConnection.TurnTraceSwitchOn();
-			}
 			else if (context is DataContext dctx)
-			{
 				dctx.OnTraceConnection = GetSqlLogAction(executionManager);
-				DataConnection.TurnTraceSwitchOn();
+			else
+			{
+				// Try to find a OnTraceConnection property in the custom context object
+				try
+				{
+					context.GetType().GetProperty("OnTraceConnection")?.SetValue(context, GetSqlLogAction(executionManager));
+				}
+				catch
+				{
+					// not our problem
+				}
 			}
 
+			DataConnection.TurnTraceSwitchOn();
+
 			return context.MappingSchema;
 
 			// Implements Linq To DB connection logging handler to feed SQL logs to LINQPad.

Source/Drivers/StaticLinqToDBDriver.cs

@@ -1,5 +1,6 @@
 using System.Data;
 using System.Data.Common;
+using System.IO;
 using LINQPad.Extensibility.DataContext;
 using LinqToDB.Data;
 using LinqToDB.Mapping;
@@ -105,7 +106,7 @@ public override object[] GetContextConstructorArguments(IConnectionInfo cxInfo)
 	/// <inheritdoc/>
 	public override void InitializeContext(IConnectionInfo cxInfo, object context, QueryExecutionManager executionManager)
 	{
-		_mappingSchema = DriverHelper.InitializeContext(cxInfo, (DataConnection)context, executionManager);
+		_mappingSchema = DriverHelper.InitializeContext(cxInfo, (IDataContext)context, executionManager);
 	}
 
 	/// <inheritdoc/>
@@ -137,10 +138,13 @@ public override void PreprocessObjectToWrite(ref object objectToWrite, ObjectGra
 
 	private void TryLoadAppSettingsJson(string? appConfigPath)
 	{
-		if (appConfigPath?.EndsWith(".json", StringComparison.OrdinalIgnoreCase) == true)
+		if (string.IsNullOrWhiteSpace(appConfigPath) || !File.Exists(appConfigPath))
+			return;
+
+		if (appConfigPath!.EndsWith(".json", StringComparison.OrdinalIgnoreCase))
 			DataConnection.DefaultSettings = AppConfig.LoadJson(appConfigPath);
 #if !NETFRAMEWORK
-		if (appConfigPath?.EndsWith(".config", StringComparison.OrdinalIgnoreCase) == true)
+		if (appConfigPath.EndsWith(".config", StringComparison.OrdinalIgnoreCase))
 			DataConnection.DefaultSettings = AppConfig.LoadAppConfig(appConfigPath);
 #endif
 	}

release-notes.md

@@ -3,6 +3,7 @@
 Issues fixed:
 
 - [#97](https://github.com/linq2db/linq2db.LINQPad/pull/97), [#103](https://github.com/linq2db/linq2db.LINQPad/pull/103): update dependencies to get rid of vulnerable transient dependencies
+- [#102](https://github.com/linq2db/linq2db.LINQPad/pull/102): support custom `IDataContext`-based contexts; don't try to load missing connection configuration files
 
 # Release 5.1.0